事件监听

事件监听

• 当某个事件发生，会产生什么？

• public class Demo01 {
      public static void main(String[] args) {
          //按下按钮，触发事件
          Frame frame = new Frame();
          Button button = new Button();
  
          //因为addActionListener需要ActionListener，因此我们需要构造一个ActionListener
          MyActionListener myActionListener = new MyActionListener();
          button.addActionListener(myActionListener);
          frame.add(button,BorderLayout.CENTER);
          frame.pack();
          frame.setVisible(true);
          windowClose(frame);
      }
      public static void windowClose(Frame frame) {
          //关闭窗口
          frame.addWindowListener(new WindowAdapter() {
              @Override
              public void windowClosing(WindowEvent e) {
                  System.exit(0);
              }
          });
      }
  
      //事件监听
      static class MyActionListener implements ActionListener{
          @Override
          public void actionPerformed(ActionEvent e) {
              System.out.println("触发事件！");
          }
      }
  }
  

• public class Demo02 {
      public static void main(String[] args) {
          //两个按钮实现同一个监听
          Frame frame = new Frame("开始-停止");
          Button button1 = new Button("start");
          Button button2 = new Button("stop");
          //可以显示的定义触发会返回的命令，如果不显示定义，则默认值
          button2.setActionCommand("按钮2-stop");
  
          Monitor monitor = new Monitor();
          button1.addActionListener(monitor);
          button2.addActionListener(monitor);
          frame.add(button1,BorderLayout.EAST);
          frame.add(button2,BorderLayout.WEST);
          frame.pack();
          frame.setVisible(true);
      }
  }
  
  class Monitor implements ActionListener{
      @Override
      public void actionPerformed(ActionEvent e) {
          //e.getActionCommand()获得按钮的信息
          System.out.println("点击"+e.getActionCommand());
  
      }
  }