【转】转帖并注释:Java中的事件处理机制--事件监听器的四种实现方式

原文地址：http://blog.sina.com.cn/s/blog_4b650d650100nqws.html

Java中四种事件监听器的实现方式分别为:

1. 自身类做为事件监听器
2. 外部类作为事件监听器
3. 匿名内部类作为事件监听器
4. 内部类作为事件监听器.

下面分别描述:

//---------------------------------------------------------------------

1. 自身类作为事件监听器:

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

     //ActionListener:java.awt.event.ActionListener(interface),用来监听Action事件
     class ThisClassEvent extends JFrame implements ActionListener
     {
         JButton btn;  

         public ThisClassEvent()
         {
             super("Java事件监听机制");
             setLayout(new FlowLayout());
             setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

             btn=new JButton("点击");
             //addActionListerner()原型为:public void addActionListener(ActionListener l)
             btn.addActionListener(this);
             getContentPane().add(btn);

             setBounds(200,200,300,160);
             setVisible(true);
         }

         /------------------------------
         //actionPerformed函数是从ActionListener中继承来的.

         public void actionPerformed (ActionEvent e)
         {
             Container c=getContentPane();
             c.setBackground(Color.red);
         } 

         /------------------------------
         public static void main(String args[])
         {
             new ThisClassEvent();
         }
     } 

2. 外部类作为事件监听器:

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

     class OuterClassEvent extends JFrame
     {
         JButton btn;
         public OuterClassEvent()
         {
              super("Java事件监听机制");
              setLayout(new FlowLayout());
              setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

              btn=new JButton("点击");

              //addActionListerner()原型为:public void addActionListener(ActionListener l)
              //new OuterClass(this)是OuterClass的实例,而OuterClass是从ActionListener继承来的
              btn.addActionListener(new OuterClass(this));
              getContentPane().add(btn);

              setBounds(200,200,300,160);
              setVisible(true);
         }

         public static void main(String args[])
         {
              new OuterClassEvent();
         }
     } 

     //外部类------------------------------

     //OuterClass从ActionListener继承
     class OuterClass implements ActionListener
     {
          OuterClassEvent oce;
          public OuterClass(OuterClassEvent oce)
          {
              this.oce = oce;
          }

          //actionPerformed函数是从ActionListener中继承来的.
          public void actionPerformed(ActionEvent e)
          {
              Container c=oce.getContentPane();
              c.setBackground(Color.red);
          }
     }

     //---------------------------------------------------------------------

3. 匿名内部类作为事件监听器:

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

     class AnonymousEvent extends JFrame
     {
         JButton btn;

         public AnonymousEvent()
         {
             super("Java事件监听机制");
             setLayout(new FlowLayout());
             setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

             btn=new JButton("点击");

             //匿名内部类---------------------------
             //addActionListerner()原型为:public void addActionListener(ActionListener l)
             btn.addActionListener
             (
                 //new ActionListener()声明了ActionListener的一个实例
                 new ActionListener()
                 {

                     //actionPerformed函数是从ActionListener中继承来的.
                     public void actionPerformed(ActionEvent e)
                     {
                         Container c=getContentPane();
                         c.setBackground(Color.red);
                     }
                 }
             );

             //------------------------------
             getContentPane().add(btn);
             setBounds(200,200,300,160);
             setVisible(true); 

         }

         public static void main(String args[])
         {
             new AnonymousEvent();
         }
     }

     //---------------------------------------------------------------------

4.内部类作为事件监听器：

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

     class InnerClassEvent extends JFrame

     {
         JButton btn;
         public InnerClassEvent()

         {
             super("Java事件监听机制");
             setLayout(new FlowLayout());
             setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

             btn=new JButton("点击");

             //addActionListerner()原型为:public void addActionListener(ActionListener l)
             btn.addActionListener(new InnerClass());
             getContentPane().add(btn);

             setBounds(200,200,300,160);
             setVisible(true);
         }

         //内部类---------------------------
         //InnerClass继承了ActionListener
         class InnerClass implements ActionListener
         {

             //actionPerformed函数是从ActionListener中继承来的.
             public void actionPerformed (ActionEvent e)
             {
                 Container c=getContentPane();
                 c.setBackground(Color.red);
             }
         }

         //------------------------------
         public static void main(String args[])

         {
             new InnerClassEvent();
         }
     }

     //---------------------------------------------------------------------