JavaSwing创建一颗简单的树JTree 二

JavaSwing创建一颗简单的树JTree 二 动态创建树知识点

案例要点：

1，给按钮添加监听器
2，getLastSelectedPathComponent()：获取用户在树形组件上选择的那个对象，但是该对象是被当作object对象类型返回的，所以对其返回值进行强制类型转换为节点类型
3, TreeSelectionListener()：用来监听用户选择节点的 *** 作，一旦用户选择了某个节点，监听器会立刻捕获到用户的动作，知道用户选择的哪一个节点，从而计算出从根节点到被选中节点的唯一路径

4，为一颗树添加新节点的核心代码，

1. 获取被选中的节点
2. 从文本框获取新节点名称
3. 添加新节点到被选中的节点
   

5，每次新增节点，都要为新增节点选中父节点，父节点是唯一的，要求树形组件是单选模式，


6，把重复语句封装成方法，我们在设计方法的时候，要把方法所涉及的工作，要从逻辑上，划分边界，不要设计一个大而全的方法，要小而专，功能明确

7，所有 *** 作，都可以再添加一个确认

案例：

代码：

package Tree.mugejiangtang;

import java.awt.Container;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.Jframe;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.JTree;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreePath;
import javax.swing.tree.TreeSelectionModel;


public class Newframe11 extends Jframe{
    JTree familyTree;
    JScrollPane jspFamily;

    JTree dynTree;
    JScrollPane jspDyn;
    DefaultMutableTreeNode treeRoot ,temp;  //temp 引用指向被选中节点
    JTextField txtName;
    JButton btnAdd,btnRename,btnDelete;
    TreePath path; //用来表示节点路径
    public Newframe11(){
        init();
    }
    private void init( ){
        Container container = this.getContentPane();//获得窗体的主体区域
        container.setLayout(null);

        treeRoot = new DefaultMutableTreeNode("根");
        dynTree = new JTree(treeRoot);
        jspDyn = new JScrollPane(dynTree);
        txtName = new JTextField();
        btnAdd = new JButton("新增");
        btnRename = new JButton("修改");
        btnDelete = new JButton("删除");

        dynTree.setFont(new Font("微软雅黑", Font.PLAIN, 18));
        //每次新增节点，都要为新增节点选中父节点，父节点是唯一的，要求树形组件是单选模式，
        dynTree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);

        dynTree.addTreeSelectionListener(new TreeSelectionListener() {

            @Override
            public void valueChanged(TreeSelectionEvent e) {    //一旦用户选择节点变化，立即执行

                path = e.getPath();
            }
        });

        jspDyn.setSize(350, 250);
        jspDyn.setLocation(400, 30);

        txtName.setSize(80, 30);
        txtName.setLocation(400, 300);
        txtName.setFont(new Font("微软雅黑", Font.PLAIN, 18));

        btnAdd.setSize(80, 30);
        btnAdd.setLocation(490, 300);
        btnAdd.setFont(new Font("微软雅黑", Font.PLAIN, 18));
        //给按钮添加监听器
        btnAdd.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                //被选中的节点，把新节点添加到他下面
                temp = (DefaultMutableTreeNode)dynTree.getLastSelectedPathComponent();
                //新节点名称
                String name = txtName.getText();

                if(validate(temp,name)==true){
                    //添加新节点
                    temp.add(new DefaultMutableTreeNode(name));
                    //想要展示节点，就要把该节点从根节点一直到该节点，全部展现出来
                    dynTree.expandPath(path);
                    //给树组件添加新节点后，不会立刻显示，需要刷新一下，才显示
                    dynTree.updateUI();
                }

            }
        });

        btnRename.setSize(80, 30);
        btnRename.setLocation(580, 300);
        btnRename.setFont(new Font("微软雅黑", Font.PLAIN, 18));
        btnRename.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                temp = (DefaultMutableTreeNode)dynTree.getLastSelectedPathComponent();
                String name = txtName.getText();
                if(validate(temp,name)==true){
                    //对树组件进行重命名的方法
                    temp.setUserObject(name);
                    dynTree.updateUI();
                }

            }
        });

        btnDelete.setSize(80, 30);
        btnDelete.setLocation(670, 300);
        btnDelete.setFont(new Font("微软雅黑", Font.PLAIN, 18));
        btnDelete.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                temp = (DefaultMutableTreeNode)dynTree.getLastSelectedPathComponent();
                if(temp==null){
                    System.out.println("请选中一个节点！");
                    return;
                }
                if(temp.isRoot()==true){
                    System.out.println("不能删除根节点！");
                    return;
                }
                temp.removeFromParent();
                dynTree.updateUI();
            }
        });

        DefaultMutableTreeNode root = new DefaultMutableTreeNode("曹 *** ");
        DefaultMutableTreeNode a1 = new DefaultMutableTreeNode("曹昂");
        DefaultMutableTreeNode a2 = new DefaultMutableTreeNode("曹丕");
        DefaultMutableTreeNode a3 = new DefaultMutableTreeNode("曹植");
        DefaultMutableTreeNode a4 = new DefaultMutableTreeNode("曹彰");
        root.add(a1);
        root.add(a2);
        root.add(a3);
        root.add(a4);
        DefaultMutableTreeNode b1 = new DefaultMutableTreeNode("曹睿");
        DefaultMutableTreeNode b2 = new DefaultMutableTreeNode("曹霖");
        DefaultMutableTreeNode b3 = new DefaultMutableTreeNode("曹志");
        a2.add(b1);
        a2.add(b2);
        a3.add(b3);
        DefaultMutableTreeNode c1 = new DefaultMutableTreeNode("曹芳");
        b1.add(c1);

        familyTree = new JTree(root);
        familyTree.setFont(new Font("微软雅黑", Font.PLAIN, 18));
        jspFamily = new JScrollPane(familyTree);
        jspFamily.setSize(300, 250);
        jspFamily.setLocation(30, 30);

        container.add(jspFamily);
        container.add(jspDyn);
        container.add(txtName);
        container.add(btnAdd);
        container.add(btnRename);
        container.add(btnDelete);

    }

    //编程，一定要防止大量重复性代码的出现，把相同代码提炼成方法
    boolean validate(DefaultMutableTreeNode node,String name){
        if(node==null){
            System.out.println("请选择一个节点！");
            return false;
        }
        name = txtName.getText();
        if(name.equals("")){
            System.out.println("请填写节点的名称");
            return false;
        }
        return true;
    }
}

测试代码：

package Tree.mugejiangtang;
import javax.swing.Jframe;
public class Test {
    public static void main(String[] args) {
        Newframe11 myframe = new Newframe11();
        myframe.setSize(800, 400);
        myframe.setLocationRelativeTo(null);
        myframe.setTitle("窗体标题");
        myframe.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);
        myframe.setVisible(true);

    }
}

自学了解：

参考链接：
https://www.bilibili.com/video/BV1JB4y1u7sM?p=35