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JavaFX 树视图

2024-04-01 分类：Java教程

JavaFX教程 – JavaFX树视图

TreeView UI控件为我们提供了一种渲染树结构的方法。 树具有包含所有分层值的根节点。

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class Main extends Application {
  public static void main(String[] args) {
    launch(args);
  }

  @Override
  public void start(Stage primaryStage) {
     TreeItem<String> rootItem = new TreeItem<>("Root");
    rootItem.setExpanded(true);

    TreeItem<String> item = new TreeItem<>("A");
    rootItem.getChildren().add(item);

    item = new TreeItem<>("B");
    rootItem.getChildren().add(item);

    TreeView<String> tree = new TreeView<>(rootItem);
    StackPane root = new StackPane();
    root.getChildren().add(tree);
    primaryStage.setScene(new Scene(root, 300, 250));
    primaryStage.show();
  }
}

上面的代码生成以下结果。


创建树视图

当创建树视图时，我们通常从构建根的TreeItem对象开始。 然后我们将根添加到树视图，并创建其他树项目对象并将它们添加到根。

我们可以通过setGraphic方法或使用它的构造函数来创建一个图形图标到树项目。 图标的建议大小为16×16。

对根项目调用的setExpanded方法定义树视图项目的初始外观。

以下代码从本地文件系统创建动态树。

import java.io.File;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class Main extends Application {
  public static void main(String[] args) {
    launch(args);
  }
  private TreeItem<File> createNode(final File f) {
    return new TreeItem<File>(f) {
      private boolean isLeaf;
      private boolean isFirstTimeChildren = true;
      private boolean isFirstTimeLeaf = true;
      @Override
      public ObservableList<TreeItem<File>> getChildren() {
        if (isFirstTimeChildren) {
          isFirstTimeChildren = false;
          super.getChildren().setAll(buildChildren(this));
        }
        return super.getChildren();
      }
      @Override
      public boolean isLeaf() {
        if (isFirstTimeLeaf) {
          isFirstTimeLeaf = false;
          File f = (File) getValue();
          isLeaf = f.isFile();
        }
        return isLeaf;
      }
      private ObservableList<TreeItem<File>> buildChildren(
          TreeItem<File> TreeItem) {
        File f = TreeItem.getValue();
        if (f == null) {
          return FXCollections.emptyObservableList();
        }
        if (f.isFile()) {
          return FXCollections.emptyObservableList();
        }
        File[] files = f.listFiles();
        if (files != null) {
          ObservableList<TreeItem<File>> children = FXCollections
              .observableArrayList();
          for (File childFile : files) {
            children.add(createNode(childFile));
          }
          return children;
        }
        return FXCollections.emptyObservableList();
      }
    };
  }
  @Override
  public void start(Stage stage) {
    Scene scene = new Scene(new Group(), 300, 300);
    VBox vbox = new VBox();
    TreeItem<File> root = createNode(new File("c:/"));
    TreeView treeView = new TreeView<File>(root);
    vbox.getChildren().add(treeView);
    ((Group) scene.getRoot()).getChildren().add(vbox);
    stage.setScene(scene);
    stage.show();
  }
}

上面的代码生成以下结果。


用户域模型

以下代码显示了如何使用用户域模型数据与TreeView。

创建Employee类以捕获用户域模型，并且代码使用循环将所有员工添加到树视图。

/*
 * Copyright (c) 2008, 2014, Oracle and/or its affiliates.
 * All rights reserved. Use is subject to license terms.
 *
 * This file is available and licensed under the following license:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  - Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the distribution.
 *  - Neither the name of Oracle nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
import java.util.Arrays;
import java.util.List;
import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
public class Main extends Application {
    List<Employee> employees = Arrays.<Employee>asList(
            new Employee("a1", "A"),
            new Employee("a2", "A"),
            new Employee("e1", "E"));
    private final Node rootIcon =  new ImageView(new Image(getClass().getResourceAsStream("root.png")));
    TreeItem<String> rootNode = new TreeItem<String>("Root",rootIcon);
    public static void main(String[] args) {
        Application.launch(args);
    }
    @Override
    public void start(Stage stage) {
        rootNode.setExpanded(true);
        for (Employee employee : employees) {
            TreeItem<String> empLeaf = new TreeItem<String>(employee.getName());
            boolean found = false;
            for (TreeItem<String> depNode : rootNode.getChildren()) {
                if (depNode.getValue().contentEquals(employee.getDepartment())){
                    depNode.getChildren().add(empLeaf);
                    found = true;
                    break;
                }
            }
            if (!found) {
                TreeItem depNode = new TreeItem(employee.getDepartment());
                rootNode.getChildren().add(depNode);
                depNode.getChildren().add(empLeaf);
            }
        }
        stage.setTitle("Tree View Sample");
        VBox box = new VBox();
        final Scene scene = new Scene(box, 400, 300);
        scene.setFill(Color.LIGHTGRAY);
        TreeView<String> treeView = new TreeView<String>(rootNode);
        treeView.setShowRoot(true);
        treeView.setEditable(true);
        box.getChildren().add(treeView);
        stage.setScene(scene);
        stage.show();
    }
    public static class Employee {
        private final SimpleStringProperty name;
        private final SimpleStringProperty department;
        private Employee(String name, String department) {
            this.name = new SimpleStringProperty(name);
            this.department = new SimpleStringProperty(department);
        }
        public String getName() {
            return name.get();
        }
        public void setName(String fName) {
            name.set(fName);
        }
        public String getDepartment() {
            return department.get();
        }
        public void setDepartment(String fName) {
            department.set(fName);
        }
    }
}

新树项目按需

/*
 * Copyright (c) 2008, 2014, Oracle and/or its affiliates.
 * All rights reserved. Use is subject to license terms.
 *
 * This file is available and licensed under the following license:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  - Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the distribution.
 *  - Neither the name of Oracle nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
import java.util.Arrays;
import java.util.List;
import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.event.ActionEvent;
import javafx.scene.Scene;
import javafx.scene.control.ContextMenu;
import javafx.scene.control.MenuItem;
import javafx.scene.control.TextField;
import javafx.scene.control.TreeCell;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
public class Main extends Application {
    List<Employee> employees = Arrays.<Employee>asList(
            new Employee("Jacob Smith", "Accounts Department"),
            new Employee("Judy Mayer", "IT Support"),
            new Employee("Gregory Smith", "IT Support"));
    TreeItem<String> rootNode = 
        new TreeItem<>("MyCompany Human Resources");
    public static void main(String[] args) {
        Application.launch(args);
    }
    @Override
    public void start(Stage stage) {
        rootNode.setExpanded(true);
        for (Employee employee : employees) {
            TreeItem<String> empLeaf = new TreeItem<>(employee.getName());
            boolean found = false;
            for (TreeItem<String> depNode : rootNode.getChildren()) {
                if (depNode.getValue().contentEquals(employee.getDepartment())){
                    depNode.getChildren().add(empLeaf);
                    found = true;
                    break;
                }
            }
            if (!found) {
                TreeItem depNode = new TreeItem(employee.getDepartment());
                rootNode.getChildren().add(depNode);
                depNode.getChildren().add(empLeaf);
            }
        }
        stage.setTitle("Tree View Sample");
        VBox box = new VBox();
        final Scene scene = new Scene(box, 400, 300);
        scene.setFill(Color.LIGHTGRAY);
        TreeView<String> treeView = new TreeView<>(rootNode);
        treeView.setEditable(true);
        treeView.setCellFactory((TreeView<String> p) -> 
            new TextFieldTreeCellImpl());
        box.getChildren().add(treeView);
        stage.setScene(scene);
        stage.show();
    }
    private final class TextFieldTreeCellImpl extends TreeCell<String> {
        private TextField textField;
        private final ContextMenu addMenu = new ContextMenu();
        public TextFieldTreeCellImpl() {
            MenuItem addMenuItem = new MenuItem("Add Employee");
            addMenu.getItems().add(addMenuItem);
            addMenuItem.setOnAction((ActionEvent t) -> {
                TreeItem newEmployee = 
                    new TreeItem<>("New Employee");
                getTreeItem().getChildren().add(newEmployee);
            });
        }
        @Override
        public void startEdit() {
            super.startEdit();
            if (textField == null) {
                createTextField();
            }
            setText(null);
            setGraphic(textField);
            textField.selectAll();
        }
        @Override
        public void cancelEdit() {
            super.cancelEdit();
            setText((String) getItem());
            setGraphic(getTreeItem().getGraphic());
        }
        @Override
        public void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);
            if (empty) {
                setText(null);
                setGraphic(null);
            } else {
                if (isEditing()) {
                    if (textField != null) {
                        textField.setText(getString());
                    }
                    setText(null);
                    setGraphic(textField);
                } else {
                    setText(getString());
                    setGraphic(getTreeItem().getGraphic());
                    if (
                        !getTreeItem().isLeaf()&&getTreeItem().getParent()!= null
                    ){
                        setContextMenu(addMenu);
                    }
                }
            }
        }
        private void createTextField() {
            textField = new TextField(getString());
            textField.setOnKeyReleased((KeyEvent t) -> {
                if (t.getCode() == KeyCode.ENTER) {
                    commitEdit(textField.getText());
                } else if (t.getCode() == KeyCode.ESCAPE) {
                    cancelEdit();
                }
            });  
        }
        private String getString() {
            return getItem() == null ? "" : getItem().toString();
        }
    }
    public static class Employee {
        private final SimpleStringProperty name;
        private final SimpleStringProperty department;
        private Employee(String name, String department) {
            this.name = new SimpleStringProperty(name);
            this.department = new SimpleStringProperty(department);
        }
        public String getName() {
            return name.get();
        }
        public void setName(String fName) {
            name.set(fName);
        }
        public String getDepartment() {
            return department.get();
        }
        public void setDepartment(String fName) {
            department.set(fName);
        }
    }
}

上面的代码生成以下结果。


单元工厂

单元工厂可以向TreeView中的单个TreeItem添加具有特殊功能的TreeCell。

/*
 * Copyright (c) 2008, 2014, Oracle and/or its affiliates.
 * All rights reserved. Use is subject to license terms.
 *
 * This file is available and licensed under the following license:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  - Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the distribution.
 *  - Neither the name of Oracle nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 import java.util.Arrays;
import java.util.List;
import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.scene.control.TreeCell;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
public class Main extends Application {
  List<Employee> employees = Arrays.<Employee> asList(new Employee(
      "Jacob Smith", "Accounts Department"), new Employee("Isabella Johnson",
      "Accounts Department"), new Employee("Mike Graham", "IT Support"),
      new Employee("Judy Mayer", "IT Support"), new Employee("Gregory Smith",
          "IT Support"));
  TreeItem<String> rootNode;
  public static void main(String[] args) {
    Application.launch(args);
  }
  public Main() {
    this.rootNode = new TreeItem<>("MyCompany Human Resources");
  }
  @Override
  public void start(Stage stage) {
    rootNode.setExpanded(true);
    for (Employee employee : employees) {
      TreeItem<String> empLeaf = new TreeItem<>(employee.getName());
      boolean found = false;
      for (TreeItem<String> depNode : rootNode.getChildren()) {
        if (depNode.getValue().contentEquals(employee.getDepartment())) {
          depNode.getChildren().add(empLeaf);
          found = true;
          break;
        }
      }
      if (!found) {
        TreeItem<String> depNode = new TreeItem<>(employee.getDepartment());
        rootNode.getChildren().add(depNode);
        depNode.getChildren().add(empLeaf);
      }
    }
    stage.setTitle("Tree View Sample");
    VBox box = new VBox();
    final Scene scene = new Scene(box, 400, 300);
    scene.setFill(Color.LIGHTGRAY);
    TreeView<String> treeView = new TreeView<>(rootNode);
    treeView.setEditable(true);
    treeView
        .setCellFactory((TreeView<String> p) -> new TextFieldTreeCellImpl());
    box.getChildren().add(treeView);
    stage.setScene(scene);
    stage.show();
  }
  private final class TextFieldTreeCellImpl extends TreeCell<String> {
    private TextField textField;
    public TextFieldTreeCellImpl() {
    }
    @Override
    public void startEdit() {
      super.startEdit();
      if (textField == null) {
        createTextField();
      }
      setText(null);
      setGraphic(textField);
      textField.selectAll();
    }
    @Override
    public void cancelEdit() {
      super.cancelEdit();
      setText((String) getItem());
      setGraphic(getTreeItem().getGraphic());
    }
    @Override
    public void updateItem(String item, boolean empty) {
      super.updateItem(item, empty);
      if (empty) {
        setText(null);
        setGraphic(null);
      } else {
        if (isEditing()) {
          if (textField != null) {
            textField.setText(getString());
          }
          setText(null);
          setGraphic(textField);
        } else {
          setText(getString());
          setGraphic(getTreeItem().getGraphic());
        }
      }
    }
    private void createTextField() {
      textField = new TextField(getString());
      textField.setOnKeyReleased((KeyEvent t) -> {
        if (t.getCode() == KeyCode.ENTER) {
          commitEdit(textField.getText());
        } else if (t.getCode() == KeyCode.ESCAPE) {
          cancelEdit();
        }
      });
    }
    private String getString() {
      return getItem() == null ? "" : getItem().toString();
    }
  }
  public static class Employee {
    private final SimpleStringProperty name;
    private final SimpleStringProperty department;
    private Employee(String name, String department) {
      this.name = new SimpleStringProperty(name);
      this.department = new SimpleStringProperty(department);
    }
    public String getName() {
      return name.get();
    }
    public void setName(String fName) {
      name.set(fName);
    }
    public String getDepartment() {
      return department.get();
    }
    public void setDepartment(String fName) {
      department.set(fName);
    }
  }
}

上面的代码生成以下结果。


树单元编辑

我们可以使用以下树单元编辑器。

  • CheckBoxTreeCell
  • ChoiceBoxTreeCell
  • ComboBoxTreeCell
  • TextFieldTreeCell

有些类扩展了TreeCell实现来渲染单元格内的特定控件。

下面的代码创建一个带有复选框树项目的树视图。

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.CheckBoxTreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.control.cell.CheckBoxTreeCell;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
public class Main extends Application {
  public static void main(String[] args) {
    launch(args);
  }
  @Override
  public void start(Stage primaryStage) {
    CheckBoxTreeItem<String> rootItem = new CheckBoxTreeItem<>("A");
    rootItem.setExpanded(true);
    TreeView tree = new TreeView(rootItem);
    tree.setEditable(true);
    tree.setCellFactory(CheckBoxTreeCell.forTreeView());
    CheckBoxTreeItem<String> checkBoxTreeItem = new CheckBoxTreeItem<>("a");
    rootItem.getChildren().add(checkBoxTreeItem);
    checkBoxTreeItem = new CheckBoxTreeItem<>("b");
    rootItem.getChildren().add(checkBoxTreeItem);
    tree.setRoot(rootItem);
    StackPane root = new StackPane();
    root.getChildren().add(tree);
    primaryStage.setScene(new Scene(root, 300, 250));
    primaryStage.show();
  }
}

上面的代码生成以下结果。


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文章名称：《JavaFX 树视图》
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