focuslistenerframe.java

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package listener;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

//使用implements关键字加入聚焦接收器
public class FocusListenerFrame extends JFrame implements FocusListener {
  JPanel contentPane;
   //创建3个编辑框
  JTextField jTextField1 = new JTextField();
  JTextField jTextField2 = new JTextField();
  JTextField jTextField3 = new JTextField();
  //创建3个标签
  JLabel jLabel1 = new JLabel();
  JLabel jLabel2 = new JLabel();
  JLabel jLabel3 = new JLabel();

  public static void main(String[] args) {
    FocusListenerFrame frame = new FocusListenerFrame();
    frame.setVisible(true);
  }

  public FocusListenerFrame() {
    //窗口关闭时清空内存
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    jbInit();
  }

  private void jbInit() {
    contentPane = (JPanel)this.getContentPane();
    contentPane.setLayout(null);
    this.setSize(new Dimension(400, 300));
    this.setTitle("聚焦接收器示例");
    jTextField1.setBounds(new Rectangle(184, 48, 143, 29));
    //加入聚焦接收器
    jTextField1.addFocusListener(this);
    jTextField2.setBounds(new Rectangle(184, 116, 143, 29));
    jTextField2.addFocusListener(this);
    jTextField3.setBounds(new Rectangle(184, 183, 143, 29));
    jTextField3.addFocusListener(this);
    jLabel1.setText("编辑框1");
    jLabel1.setBounds(new Rectangle(63, 48, 79, 16));
    jLabel2.setText("编辑框2");
    jLabel2.setBounds(new Rectangle(63, 116, 61, 16));
    jLabel3.setText("编辑框3");
    jLabel3.setBounds(new Rectangle(63, 183, 86, 16));
    contentPane.add(jTextField1, null);
    contentPane.add(jTextField2, null);
    contentPane.add(jTextField3, null);
    contentPane.add(jLabel1, null);
    contentPane.add(jLabel2, null);
    contentPane.add(jLabel3, null);
  }
  //当控件获得焦点时,执行下面代码
  public void focusGained(FocusEvent e) {
    displayMessage("获得焦点", e);
  }
  //当按件失去焦点时,执行下面代码
  public void focusLost(FocusEvent e) {
    displayMessage("失去焦点", e);
  }

  //显示信息方法
  void displayMessage(String infor, FocusEvent e) {
    //取得激发聚焦事件的控件
    JTextField tempTextField = (JTextField)e.getSource();
    //设置编辑框的字符串
    tempTextField.setText(infor);
  }
}