javaFx 工具开发 完

package sample;import javafx.application.Application;import javafx.event.EventHandler;import javafx.scene.Scene;import javafx.scene.control.Alert;import javafx.scene.control.Button;import javafx.scene.input.MouseEvent;import javafx.scene.layout.BorderPane;import javafx.stage.Stage;public class demo1 extends Application{    @Override    public void start(Stage primaryStage) throws Exception {        BorderPane root = new BorderPane();        Button b1 = new Button("点我");        b1.setOnMouseClicked(new EventHandler<MouseEvent>() {            @Override            public void handle(MouseEvent event) {                Alert alert = new Alert(Alert.AlertType.WARNING);                alert.setHeaderText("弹窗");                alert.setContentText("你好呀");                alert.show();            }        });        root.setCenter(b1);        primaryStage.setTitle("鼠标操作");        primaryStage.setScene(new Scene(root,500,50));        primaryStage.show();    }}

package sample;import javafx.application.Application;import javafx.event.ActionEvent;import javafx.event.EventHandler;import javafx.geometry.Insets;import javafx.scene.Scene;import javafx.scene.control.Alert;import javafx.scene.control.Button;import javafx.scene.control.PasswordField;import javafx.scene.control.TextField;import javafx.scene.layout.BorderPane;import javafx.scene.layout.VBox;import javafx.stage.Stage;import java.sql.*;public class DemoAlert extends Application {    @Override    public void start(Stage primaryStage) throws Exception {        // 文本框和密码框        TextField user = new TextField();        PasswordField pwd = new PasswordField();        Button login = new Button("登录");        // 创建布局        BorderPane root = new BorderPane();        VBox vBox = new VBox();        vBox.getChildren().addAll(user,pwd,login);        // 容器边距        vBox.setSpacing(10);        // 子父容器间距        vBox.setPadding(new Insets(80));        root.setCenter(vBox);        login.setOnAction(new EventHandler<ActionEvent>() {            @Override            public void handle(ActionEvent event) {                String username = user.getText();                String pass = pwd.getText();                Alert warn = new Alert(Alert.AlertType.WARNING);                // 获取当前数据库链接                try {                    Class.forName("com.mysql.jdbc.Driver");                    Connection conn = DriverManager.getConnection("jdbc:mysql:///db4", "root", "root");                    Statement stmt = conn.createStatement();                    String sql = "select * from user where username ='"+username+"' and passwd = '"+pass+"' ";                    System.out.println(sql);                    ResultSet rs = stmt.executeQuery(sql);                    if (rs.next()){                        warn.setHeaderText("正在登录 请稍等");                        warn.setContentText("登录成功");                        warn.show();                    } else {                        warn.setHeaderText("正在查询 请稍等");                        warn.setContentText("账号或密码错误，禁止登陆");                        warn.show();                    }                    stmt.close();                    conn.close();                } catch (ClassNotFoundException e) {                    e.printStackTrace();                } catch (SQLException e) {                    e.printStackTrace();                }            }        });        primaryStage.setTitle("提示框");        primaryStage.setScene(new Scene(root,400,300));        primaryStage.show();    }}

Dialog：用于显示一个自定义的对话框Dialog  -->  DialogPane --> (node + button)Dialog 里要设置一个DialogPane    Dialog.setDialogPane()DialogPane里要设置根节点和按钮    DialogPane.setContent()    DialogPane.getButtonTypes().add()

package sample.Dailog;public class Student {    public int id = 0;    public String name;    public String phone;    public Student(){}    public Student(int id, String name, String phone) {        this.id = id;        this.name = name;        this.phone = phone;    }    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPhone() {        return phone;    }    public void setPhone(String phone) {        this.phone = phone;    }}

package sample.Dailog;import javafx.scene.control.TreeItem;import javafx.scene.control.TreeTableCell;import javafx.scene.control.TreeTableColumn;import javafx.scene.control.TreeTableView;import javafx.util.Callback;import java.util.List;public class StudentPane extends TreeTableView<Student> {    // 根节点    TreeItem rootItem = new TreeItem(new Student());    // 设置3列    TreeTableColumn<Student, Student> columns[] = new TreeTableColumn[3];    public StudentPane(){        // 初始化设置        initColumns();        // 扁平化显示 不显示根节点        setRoot( rootItem);        setShowRoot(false);    }    // 清空    public  void clear(){        rootItem.getChildren().clear();    }    // 添加    public void  add(List<Student> datalist){        for (Student fi : datalist) {            TreeItem item = new TreeItem(fi);            rootItem.getChildren().add(item);        }    }    public  void add(Student data) {        TreeItem item = new TreeItem(data);        rootItem.getChildren().add(item);    }    @Override    protected void layoutChildren() {        super.layoutChildren();        // 动态设置列宽        double w = this.getWidth();        double w0 = w * 0.3;        double w1 = w * 0.4;        double w2 = w - w0 - w1- 20;        columns[0].setPrefWidth(w0);        columns[1].setPrefWidth(w1);        columns[2].setPrefWidth(w2);    }    private void initColumns() {        // 添加多个列        columns[0] = new TreeTableColumn("学号");        columns[1] = new TreeTableColumn("姓名");        columns[2] = new TreeTableColumn("手机号");        this.getColumns().addAll(columns);        // 设置 CellValueFactory (此段写法固定)        Callback cellValueFactory = new Callback() {            @Override            public Object call(Object param) {                TreeTableColumn.CellDataFeatures p = (TreeTableColumn.CellDataFeatures)param;                return p.getValue().valueProperty();            }        };        for(int i=0; i<columns.length; i++) {            columns[i].setCellValueFactory(cellValueFactory);        }        // 设置CellFactory，定义每一列的单元格的显示        // 这里使用了lambda表达式，否则写起来太长了！        columns[0].setCellFactory((param)->{            return new MyTreeTableCell("c0");        });        columns[1].setCellFactory((param)->{            return new MyTreeTableCell("c1");        });        columns[2].setCellFactory((param)->{            return new MyTreeTableCell("c2");        });    }    // 单元格的显示    static class MyTreeTableCell extends TreeTableCell<Student,Student> {        String columnID;        public MyTreeTableCell(String columnID) {            this.columnID = columnID;        }        @Override        protected void updateItem(Student item, boolean empty) {            super.updateItem(item, empty);            if (empty || item == null) {                setText(null);                setGraphic(null);            } else {                setGraphic(null);                if(columnID.equals("c0")) {                    setText(String.valueOf(item.id));                }                else if(columnID.equals("c1")) {                    setText(String.valueOf(item.name));                }                else if(columnID.equals("c2")) {                    setText(String.valueOf(item.phone));                }            }        }    }}

package sample.Dailog;import javafx.event.ActionEvent;import javafx.event.EventHandler;import javafx.scene.control.Button;import javafx.scene.control.Dialog;import javafx.scene.control.DialogPane;import javafx.scene.control.TextField;import javafx.scene.layout.VBox;public class AddStudentDailog extends Dialog<Boolean> {    // 添加信息面板    TextField id = new TextField();    TextField name = new TextField();    TextField phone = new TextField();    public AddStudentDailog(){        VBox vBox = new VBox();        id.setPromptText("学号");        name.setPromptText("姓名");        phone.setPromptText("手机号");        // 添加到vbox        vBox.getChildren().addAll(id,name,phone);        // 创建dialogpane        DialogPane dialogPane = new DialogPane();        dialogPane.setContent(vBox);        // 创建按钮        Button ok = new Button("确定");        vBox.getChildren().add(ok);        ok.setOnAction(new EventHandler<ActionEvent>() {            @Override            public void handle(ActionEvent event) {                // 设置结果 关闭对话框                setResult(true);            }        });        // 创建对话框        setDialogPane(dialogPane);        setTitle("添加学生信息");    }    private boolean checkValid(){        return true;    }    public Student getValue(){        Student v = new Student();        v.id = Integer.valueOf( id.getText() );        v.name = name.getText();        v. phone = phone.getText();        return v;    }}

package sample.Dailog;import javafx.application.Application;import javafx.event.ActionEvent;import javafx.event.EventHandler;import javafx.scene.Scene;import javafx.scene.control.Button;import javafx.scene.layout.BorderPane;import javafx.stage.Stage;import java.util.Optional;public class Main extends Application{    public StudentPane studentPane;    @Override    public void start(Stage primaryStage) throws Exception {        studentPane =new StudentPane();        BorderPane root = new BorderPane();        root.setCenter(studentPane);        primaryStage.setScene(new Scene(root, 500, 400));        primaryStage.setTitle("学生管理系统");        primaryStage.show();        Button add = new Button("添加");        root.setTop(add);        add.setOnAction(new EventHandler<ActionEvent>() {            @Override            public void handle(ActionEvent event) {                onAdd();            }        });    }    private void onAdd() {        AddStudentDailog dlg = new AddStudentDailog();        Optional<Boolean> result = dlg.showAndWait();        if( result.isPresent() && result.get() == true) {            Student s = dlg.getValue(); // getValue()是自己添加的方法            studentPane.add(s);        }    }}

package sample.FileChoose;import java.io.*;public class TextUtils {    public static String read(File f, String charset) throws IOException {        // 文件读取        FileInputStream fis = new FileInputStream(f);        int filesize = (int)f.length();        byte[] bytes = new byte[filesize];        fis.read(bytes);        fis.close();        return new String(bytes,charset);    }    // 文件写入    public static void write(File f,String text,String charset) throws IOException {        FileOutputStream fos = new FileOutputStream(f);        fos.write(text.getBytes( charset));        fos.close();    }}

package sample.FileChoose;import javafx.application.Application;import javafx.geometry.Insets;import javafx.scene.Scene;import javafx.scene.control.Button;import javafx.scene.layout.BorderPane;import javafx.scene.layout.HBox;import javafx.scene.web.HTMLEditor;import javafx.stage.FileChooser;import javafx.stage.Stage;import java.io.File;import java.io.IOException;public class Main extends Application {    // 创建编辑器    HTMLEditor editor = new HTMLEditor();    BorderPane root = new BorderPane();    @Override    public void start(Stage primaryStage) throws Exception {        Button btnOpen = new Button("打开");        Button btnSave = new Button("保存");        HBox toolbar = new HBox();        toolbar.getChildren().addAll(btnOpen, btnSave);        toolbar.setPadding(new Insets(4));        toolbar.setSpacing(4);        root.setTop(toolbar);        root.setCenter(editor);        primaryStage.setTitle("文本编辑");        primaryStage.setScene(new Scene(root, 640, 500));        primaryStage.show();        btnOpen.setOnAction(event -> {            // 选择一个文件控制器            FileChooser fileChooser = new FileChooser();            fileChooser.setTitle("打开文件");            fileChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter("Text Files", "*.txt"));            // 可以从任意控件 Node 获取到 Window 对象，传给showOpenDialog()            // Node.getScene().getWindow()            File selectedFile = fileChooser.showOpenDialog(root.getScene().getWindow());            if(selectedFile == null) {                return; // 用户没有选中文件, 已经取消操作            }            try {                String text = TextUtils.read(selectedFile,"GBK");                editor.setHtmlText(text);            } catch (IOException e) {                e.printStackTrace();            }        });        btnSave.setOnAction(event -> {            FileChooser fileChooser = new FileChooser();            fileChooser.setTitle("保存文件");            fileChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter("Text Files", "*.txt"));            // 选择文件            File selectedFile = fileChooser.showSaveDialog(root.getScene().getWindow());            if(selectedFile == null) {                return; // 用户没有选中文件, 已经取消操作            }            try {                // 获取编辑器内容                String text = editor.getHtmlText();                // 写内容                TextUtils.write(selectedFile, text, "GBK");            }catch(Exception e) {                e.printStackTrace();            }        });    }}

package sample.FileChoose;import java.io.*;public class TextUtils {    public static String read(File f, String charset) throws IOException {        // 文件读取        FileInputStream fis = new FileInputStream(f);        int filesize = (int)f.length();        byte[] bytes = new byte[filesize];        fis.read(bytes);        fis.close();        return new String(bytes,charset);    }    // 文件写入    public static void write(File f,String text,String charset) throws IOException {        FileOutputStream fos = new FileOutputStream(f);        fos.write(text.getBytes( charset));        fos.close();    }}

package sample.FileChoose;import javafx.application.Application;import javafx.application.Platform;import javafx.event.ActionEvent;import javafx.scene.Scene;import javafx.scene.control.Menu;import javafx.scene.control.MenuBar;import javafx.scene.control.MenuItem;import javafx.scene.control.SeparatorMenuItem;import javafx.scene.layout.BorderPane;import javafx.scene.web.HTMLEditor;import javafx.stage.FileChooser;import javafx.stage.Stage;import java.io.File;public class DemoMeme  extends Application {    Stage primaryStage;// 主窗口    MenuBar menuBar = new MenuBar();    HTMLEditor editor = new HTMLEditor();    @Override    public void start(Stage primaryStage) {        this.primaryStage = primaryStage;            initMenu();            BorderPane root = new BorderPane();            root.setTop(menuBar);            root.setCenter(editor);            primaryStage.setScene(new Scene(root, 600, 400));            primaryStage.show();    }    private void initMenu() {        Menu menuFile = new Menu("文件");        Menu menuHelp = new Menu("帮助");        menuBar.getMenus().addAll(menuFile, menuHelp);        MenuItem menuItemOpen = new MenuItem("打开");        MenuItem menuItemSave = new MenuItem("保存");        SeparatorMenuItem separator = new SeparatorMenuItem();        MenuItem menuItemExit = new MenuItem("退出程序");        menuFile.getItems().addAll(menuItemOpen, menuItemSave, separator, menuItemExit);        // 简写为 lambda 表达式        menuItemOpen.setOnAction((ActionEvent e)->{            onOpen();        });        menuItemSave.setOnAction((ActionEvent e)->{            onSave();        });        menuItemExit.setOnAction((ActionEvent e)->{            Platform.exit();        });    }    // 打开一个 *.txt 文件    private void onOpen(){        FileChooser fileChooser = new FileChooser();        fileChooser.setTitle("打开文件");        fileChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter("Text Files", "*.txt"));        File selectedFile = fileChooser.showOpenDialog(primaryStage);        if(selectedFile == null) return; // 用户没有选中文件, 已经取消操作        try {            String text = TextUtils.read(selectedFile, "GBK");            editor.setHtmlText(text);        }catch(Exception e)        {            e.printStackTrace();        }    }    // 保存到文件    private void onSave(){        FileChooser fileChooser = new FileChooser();        fileChooser.setTitle("保存文件");        fileChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter("Text Files", "*.txt"));        File selectedFile = fileChooser.showSaveDialog(primaryStage);        if(selectedFile == null) return; // 用户没有选中文件, 已经取消操作        try {            String text = editor.getHtmlText();            TextUtils.write(selectedFile, text, "GBK");        }catch(Exception e)        {            e.printStackTrace();        }    }}

package memu;import javafx.application.Application;import javafx.collections.FXCollections;import javafx.collections.ObservableList;import javafx.event.ActionEvent;import javafx.stage.Stage;import javafx.util.Callback;import javafx.scene.Scene;import javafx.scene.control.ContextMenu;import javafx.scene.control.ListCell;import javafx.scene.control.ListView;import javafx.scene.control.MenuItem;import javafx.scene.layout.BorderPane;public class Main extends Application {    // 创建ListView，指定数据项类型    ListView<Student> listView = new ListView<Student>();    // 数据源    ObservableList<Student> listData = FXCollections.observableArrayList();    // ListView的上下文菜单    ContextMenu listContextMenu = new ContextMenu();    @Override    public void start(Stage primaryStage) {            // 准备数据            listData.add(new Student(1, "张三", true));            listData.add(new Student(2, "李四", true));            listData.add(new Student(3, "王五", false));            // 设置数据源            listView.setItems(listData);            // 设置单元格生成器 （工厂）            listView.setCellFactory(new Callback<ListView<Student>, ListCell<Student>>() {                @Override                public ListCell<Student> call(ListView<Student> param) {                    return new MyListCell();                }            });            initContextMenu();            BorderPane root = new BorderPane();            root.setCenter(listView);            Scene scene = new Scene(root, 400, 400);            primaryStage.setScene(scene);            primaryStage.show();    }    // 初始化上下文菜单    private void initContextMenu() {        MenuItem menuItemRemove = new MenuItem("删除");        menuItemRemove.setOnAction((ActionEvent e) -> {            removeItem();        });        // 添加菜单项        listContextMenu.getItems().add(menuItemRemove);        // 给ListView设置上下文菜单        listView.setContextMenu(listContextMenu);    }    // 删除当前选中的项    private void removeItem() {        int index = listView.getSelectionModel().getSelectedIndex();        if(index >= 0) {            listData.remove(index);        }    }    // 负责单元格Cell的显示    static class MyListCell extends ListCell<Student> {        @Override        public void updateItem(Student item, boolean empty) {            // FX框架要求必须先调用 super.updateItem()            super.updateItem(item, empty);            // 自己的代码            if (item == null) {                this.setText(""); // 清空显示            } else {                this.setText(item.name); // 显示该项的值            }        }    }    // 数据项    static class Student {        public int id;        public String name;        public boolean sex;        public Student() {}        public Student(int id, String name, boolean sex){            this.id = id;            this.name = name;            this.sex = sex;        }    }}

package memu;import javafx.scene.control.ButtonType;import javafx.scene.control.Dialog;import javafx.scene.control.DialogEvent;import javafx.scene.control.DialogPane;import javafx.scene.control.TextField;import javafx.scene.control.Alert.AlertType;import javafx.scene.control.ButtonBar.ButtonData;import javafx.event.ActionEvent;import javafx.event.EventHandler;import javafx.scene.control.Alert;import javafx.scene.control.Button;import javafx.scene.layout.VBox;import javafx.util.Callback;// Dialog<Boolean> : showAndWait() 将返回Boolean值public class AddStudentDialog extends Dialog<Boolean> {  TextField id = new TextField();  TextField name = new TextField();  TextField phone = new TextField();  public AddStudentDialog() {    // 对话框内容    VBox content = new VBox();    id.setPromptText("学号");    name.setPromptText("姓名");    phone.setPromptText("手机号");    content.setSpacing(10);    content.getChildren().addAll(id, name, phone);    // Dialog -> DialogPane -> Root Node    DialogPane dialogPane = new DialogPane();        dialogPane.setContent(content);    // 添加按钮    ButtonType ok = new ButtonType("确定", ButtonData.OK_DONE);    dialogPane.getButtonTypes().add(ok);    ButtonType cancel = new ButtonType("取消", ButtonData.CANCEL_CLOSE);    dialogPane.getButtonTypes().add(cancel);    this.setResultConverter(new Callback<ButtonType,Boolean>(){      @Override      public Boolean call(ButtonType b) {        if(b.getButtonData() == ButtonData.OK_DONE)          return true;        return false;      }          });    // 创建对话框    this.setDialogPane(dialogPane);    this.setTitle("添加学生信息");  }  private boolean checkValid() {    int n = 0;    try {      n = Integer.valueOf( id.getText().trim() );          }catch(Exception e) {    }    if(n <=0) {      Alert warning = new Alert(AlertType.WARNING);      warning.setHeaderText(null);      warning.setContentText("学号输入错误！请输入整数!");      warning.showAndWait();      return false;    }    return true;  }  // 获取用户输入的值  public Student getValue() {    try {      Student v = new Student();        v.id = Integer.valueOf( id.getText() );        v.name = name.getText();        v. phone = phone.getText();        return v;    }catch(Exception e) {      e.printStackTrace();      return null;    }  }}package memu;public class Student {  public int id = 0;  public String name;  public String phone;  public Student(){}  public Student(int id, String name, String phone) {    this.id = id;    this.name = name;    this.phone = phone;  }  public int getId(){    return id;  }  public void setId(int id){    this.id = id;  }  public String getName(){    return name;  }  public void setName(String name){    this.name = name;  }  public String getPhone(){    return phone;  }  public void setPhone(String phone){    this.phone = phone;  }}package memu;import java.util.ArrayList;import java.util.List;import javafx.collections.ObservableList;import javafx.scene.control.TreeItem;import javafx.scene.control.TreeTableCell;import javafx.scene.control.TreeTableColumn;import javafx.scene.control.TreeTableView;import javafx.scene.control.TreeTableColumn.CellDataFeatures;import javafx.util.Callback;public class StudentPane extends TreeTableView<Student> {  // 根节点  TreeItem rootItem = new TreeItem(new Student());  // 列  TreeTableColumn<Student, Student> columns[] = new TreeTableColumn[3];  public StudentPane() {    // 初始化列的设置    initColumns();    // 扁平化显示, 不显示根节点, 但必须要有根节点    this.setRoot(rootItem);    this.setShowRoot(false);  }  // 清空  public void clear(){    rootItem.getChildren().clear();  }  // 添加  public void add(List<Student> datalist) {    for (Student fi : datalist) {      TreeItem item = new TreeItem(fi);      rootItem.getChildren().add(item);    }  }  public void add(Student data) {    TreeItem item = new TreeItem(data);    rootItem.getChildren().add(item);  }  public void remove(int index){    rootItem.getChildren().remove(index);  }  public List<Student> get(){    ArrayList<Student> results = new ArrayList<Student>();    ObservableList<TreeItem<Student>> items = rootItem.getChildren();    for (int i = 0; i < items.size(); i++) {      TreeItem<Student> item = items.get(i);      Student value = item.getValue();      results.add(value);    }    return results;  }  @Override  protected void layoutChildren(){    super.layoutChildren();    // 动态设置列宽    double w = this.getWidth();    double w0 = w * 0.3;    double w1 = w * 0.4;    double w2 = w - w0 - w1 - 20;    columns[0].setPrefWidth(w0);    columns[1].setPrefWidth(w1);    columns[2].setPrefWidth(w2);  }  private void initColumns() {    // 添加多个列    columns[0] = new TreeTableColumn("学号");    columns[1] = new TreeTableColumn("姓名");    columns[2] = new TreeTableColumn("手机号");    this.getColumns().addAll(columns);    // 重写layoutChildren() 动态调整个列的列宽    // 设置 CellValueFactory (此段写法固定)    Callback cellValueFactory = new Callback() {      @Override      public Object call(Object param) {        CellDataFeatures p = (CellDataFeatures) param;        return p.getValue().valueProperty();      }    };    for (int i = 0; i < columns.length; i++) {      columns[i].setCellValueFactory(cellValueFactory);    }    // 设置CellFactory，定义每一列的单元格的显示    // 这里使用了lambda表达式，否则写起来太长了！    columns[0].setCellFactory((param) -> {      return new MyTreeTableCell("c0");    });    columns[1].setCellFactory((param) -> {      return new MyTreeTableCell("c1");    });    columns[2].setCellFactory((param) -> {      return new MyTreeTableCell("c2");    });  }  // 单元格的显示  static class MyTreeTableCell extends TreeTableCell<Student, Student> {    String columnID;    public MyTreeTableCell(String columnID){      this.columnID = columnID;    }    @Override    protected void updateItem(Student item, boolean empty) {      super.updateItem(item, empty);      if (empty || item == null) {        setText(null);        setGraphic(null);      } else {        setGraphic(null);        if (columnID.equals("c0")) {          setText(String.valueOf(item.id));        } else if (columnID.equals("c1")) {          setText(String.valueOf(item.name));        } else if (columnID.equals("c2")) {          setText(String.valueOf(item.phone));        }      }    }  }}package memu;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;public class TextUtils {    public static String read(File f, String charset) throws IOException {        // 文件读取        FileInputStream fis = new FileInputStream(f);        int filesize = (int)f.length();        byte[] bytes = new byte[filesize];        fis.read(bytes);        fis.close();        return new String(bytes,charset);    }    // 文件写入    public static void write(File f,String text,String charset) throws IOException {        FileOutputStream fos = new FileOutputStream(f);        fos.write(text.getBytes( charset));        fos.close();    }}package memu;import java.io.File;import java.io.IOException;import java.util.ArrayList;import java.util.List;import java.util.Optional;import org.json.JSONArray;import org.json.JSONObject;import javafx.application.Application;import javafx.application.Platform;import javafx.event.ActionEvent;import javafx.stage.FileChooser;import javafx.stage.Stage;import javafx.stage.FileChooser.ExtensionFilter;import javafx.scene.Scene;import javafx.scene.control.ContextMenu;import javafx.scene.control.Menu;import javafx.scene.control.MenuBar;import javafx.scene.control.MenuItem;import javafx.scene.control.SeparatorMenuItem;import javafx.scene.layout.BorderPane;public class Main extends Application {  Stage primaryStage;// 主窗口  MenuBar menuBar = new MenuBar();  StudentPane studentPane = new StudentPane();  // 上下文菜单  ContextMenu contextMenu = new ContextMenu();  @Override  public void start(Stage primaryStage) {      initMenuBar(); // 初始化菜单栏      initContextMenu(); // 初始化右键菜单      BorderPane root = new BorderPane();      root.setTop(menuBar);      root.setCenter(studentPane);      primaryStage.setScene(new Scene(root, 400, 400));      primaryStage.show();  }  private void initMenuBar() {        Menu menuFile = new Menu("文件");        Menu menuHelp = new Menu("帮助");        menuBar.getMenus().addAll(menuFile, menuHelp);        MenuItem menuItemOpen = new MenuItem("打开");        MenuItem menuItemSave = new MenuItem("保存");        SeparatorMenuItem separator = new SeparatorMenuItem();        MenuItem menuItemExit = new MenuItem("退出程序");        menuFile.getItems().addAll(menuItemOpen, menuItemSave, separator, menuItemExit);    // 简写为 lambda 表达式        menuItemOpen.setOnAction((ActionEvent e)->{      try {        onOpen();      } catch (IOException ex) {        ex.printStackTrace();      }    });        menuItemSave.setOnAction((ActionEvent e)->{      try {        onSave();      } catch (IOException ex) {        ex.printStackTrace();      }    });        menuItemExit.setOnAction((ActionEvent e)->{      Platform.exit();    });  }  // 打开一个文件  private void onOpen() throws IOException {    FileChooser fileChooser = new FileChooser();    fileChooser.setTitle("打开文件");    fileChooser.getExtensionFilters().add(new ExtensionFilter("学生数据文件", "*.data"));    File selectedFile = fileChooser.showOpenDialog(primaryStage);    if(selectedFile == null) return; // 用户没有选中文件, 已经取消操作      String text = TextUtils.read(selectedFile, "GBK");      JSONArray jarray = new JSONArray(text);      List<Student> sss = new ArrayList<Student>();      for(int i = 0;i<jarray.length(); i++)      {        JSONObject jobj = jarray.getJSONObject(i);        Student s = new Student();        s.id = jobj.getInt("id");        s.name = jobj.getString("name");        s.phone = jobj.getString("phone");        sss.add( s );      }      studentPane.clear();      studentPane.add(sss);  }  // 保存到文件  private void onSave() throws IOException {    FileChooser fileChooser = new FileChooser();    fileChooser.setTitle("保存文件");    fileChooser.getExtensionFilters().add(new ExtensionFilter("学生数据文件", "*.data"));    File selectedFile = fileChooser.showSaveDialog(primaryStage);    if(selectedFile == null) return; // 用户没有选中文件, 已经取消操作      List<Student> sss = studentPane.get();      JSONArray jarray = new JSONArray(sss);      String text = jarray.toString(2);      TextUtils.write(selectedFile, text, "GBK");  }  // 初始化上下文菜单  private void initContextMenu() {    MenuItem menuItemAdd = new MenuItem("添加");    menuItemAdd.setOnAction((ActionEvent e) -> {      addItem();    });    MenuItem menuItemRemove = new MenuItem("删除");    menuItemRemove.setOnAction((ActionEvent e) -> {      removeItem();    });    // 添加菜单项    contextMenu.getItems().addAll(menuItemAdd, menuItemRemove);    // 给ListView设置上下文菜单    studentPane.setContextMenu(contextMenu);  }  // 点菜单项 '添加'  private void addItem() {    AddStudentDialog dlg = new AddStudentDialog();    Optional<Boolean> result = dlg.showAndWait();    if( result.isPresent() && result.get() == true) {      Student s = dlg.getValue(); // getValue()是自己添加的方法      studentPane.add(s );    }  }  // 点菜单项 '删除'  private void removeItem() {    int index = studentPane.getSelectionModel().getSelectedIndex();    if(index >= 0){      studentPane.remove(index);    }  }}