GUI事件监听

事件监听
理解：当某个事件发生得时候，需要干什么

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class TestActionEvent {
    public static void main(String[] args) {
        //按下按钮得时候，触发一些事件
        Frame frame = new Frame();

        Button button = new Button();
        //因为addActionListener();需要一个 ActionListener，所以
        //我们需要构造一个 ActionListener；
        MyActionListener myActionListener=new MyActionListener();
        button.addActionListener(myActionListener);

        frame.add(button, BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
        //关闭窗口
        windowClose(frame);

    }
    //关闭窗体得事件
    private  static  void windowClose(Frame frame){
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }
}
class MyActionListener implements ActionListener{
    @Override
    public void actionPerformed(ActionEvent e)
    {
        System.out.println("aaa");
    }

    }

创建得按钮，每次按下会输出aaa

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class TestActionEvent2 {
    public static void main(String[] args) {
        //两个按钮，实现同一个监听
        //例如 开始  停止
        Frame frame =new Frame("开始-停止");
        Button button1=new Button("start");
        Button button2=new Button("stop");

        //可以显示得定义触发会返回得命令，如果不显示定义，则会是默认的值
        //可以多个按钮只写一个监听类，看类里面的if
            button2.setActionCommand("button2-stop");
            MyMonitor myMoitor=new MyMonitor();
            frame.add(button1,BorderLayout.NORTH);
            frame.add(button2,BorderLayout.SOUTH);
            frame.pack();
            frame.setVisible(true);
        button1.addActionListener(myMoitor);
        button2.addActionListener(myMoitor);
        //关闭窗口
        windowClose(frame);
    }
    //关闭窗体得事件
    private  static  void windowClose(Frame frame){
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }
}
class MyMonitor implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e)
    {
        //e.getActionCommand()获得按钮的信息
        System.out.println("按钮被点击：msg"+ e.getActionCommand());
        //可以进行这样得操作
        if(e.getActionCommand().equals("start")) {
            System.out.println("Welcome");
        }
        else
        {
            System.out.println("Goodbye");
        }

    }

}

图片说明
多个按钮，共享一个监听事件