java AWT事件处理

事件处理的过程中，主要涉及3类对象：
Event Source(事件源)：事件发生的声所，如按钮，窗口，菜单等组件。
Event(事件)：事件封装了GUI组件上发生的特定事情（通常是一次用打操作）。
Event Listener(事件监听器)：负责监听事件源所发生的事件，并对各种事件做出响应处理。

实现AWT事件处理机制的步骤如下：
1.实现事件监听器类，该监听器类是一个特殊的java类，必须实现一个XxxListener接口。
2.创建普通组件（事件源），创建事件监听器对象。
3.调用addXxxListener()方法将事件监听器对象注册给普通组件（事件源）。当事件源上发生指定事件时，AWT会触发事件监听器，由事件监听器调用相应的方法（事件处理器）来处理事件，事件源上所发生的事件会作为参数传入事件处理器。

AWT的事件类都是AWTEvent类的子类，AWTEvent是EventObject的子类。
AWT事件分为两在类：低级事件和高组事件。
1.低级事件：
低级事件是指基于特定动作的事件.比如进入,点击,拖入等动作的鼠标事件,当组件得到焦点失去焦点时触发的事件.
ComponentEvent：组件事件,当组件尺寸发生变化,位置发生移动,显示/隐藏状态发生改变时触发该事件.
ContainerEvent：容器事件，当容器里发生添加级件，删除组件时触发该事件。
WindowEvent:窗口事件，当窗口状态发生改变（如打开，关闭，最大化，最小化）时触发该事件。
FocusEvent：焦点事件，当级件得到焦点或失去焦点时触发该事件。
KeyEvent:键盘事件，当按键被按下，松开单击时触发该事件。
MouseEvent:鼠标事件，当进行单击，按下，松开，移动鼠标等动作时触发该事件。

PaintEvent：组件绘制事件，该事件是一件特殊的事件类型，当GUI组件调用update/paint方法来呈现自身时触发该事件，该事件并非专用于事件处理模型。
2.高级事件（语义事件）
高级事件是基于语义的事件，它可以不和特定的动作相关联，而依赖于触发此事件的类。比如，在TextField中按Enter键会触发ActionEvent事件，在滑动条上称动滑块会触发AdjustmentEvent事件，选中项目列表的某一项就会触发ItemEvent事件。
ActionEvent：动作事件，当按钮，菜单项被单击，在TextField中按Enter键时触发该事件。
AdjustmentEvent:调节事件，在滑动条上称动滑块以调节数值时触发该事件。
ItemEvent：选项事件，当用户选中某项，或取消选中某项时触发该事件。
TextEvent：文本事件，当文本框，文本域里的文本发生改变时触发该事件。

一件级件被多个监听器监听：

package javaAWT;import java.awt.BorderLayout;import java.awt.Button;import java.awt.Frame;import java.awt.Panel;import java.awt.TextArea;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;public class MultiListener {    private Frame frame = new Frame("MultiListener");    private TextArea textArea = new TextArea(10, 35);    private Button btn1 = new Button("one");    private Button btn2 = new Button("two");    public void init() {        FirstListener f1 = new FirstListener();        btn1.addActionListener(f1);        btn1.addActionListener(new SecondListener());        btn2.addActionListener(f1);        frame.add(textArea);        Panel panel = new Panel();        panel.add(btn1);        panel.add(btn2);        frame.add(panel, BorderLayout.SOUTH);        frame.pack();        frame.setVisible(true);    }    class FirstListener implements ActionListener{        @Override        public void actionPerformed(ActionEvent e) {            // TODO Auto-generated method stub            textArea.append("FirstListener, EventSource :" + e.getActionCommand() + "\n");        }    }    class SecondListener implements ActionListener {        @Override        public void actionPerformed(ActionEvent e) {            // TODO Auto-generated method stub            textArea.append("Clicked:" + e.getActionCommand() + " Button\n");        }    }    public static void main(String[] args) {        new MultiListener().init();    }}

窗口监听 (WindowListener ):

package javaAWT;import java.awt.Frame;import java.awt.TextArea;import java.awt.event.WindowEvent;import java.awt.event.WindowListener;public class WindowListenerTest {    private Frame frame = new Frame("WindowListener");    private TextArea tArea = new TextArea(6, 40);    public void init() {        frame.addWindowListener(new MyListener());        frame.add(tArea);        frame.pack();        frame.setVisible(true);    }    class MyListener implements WindowListener {        @Override        public void windowOpened(WindowEvent e) {            // TODO Auto-generated method stub            tArea.append("窗口初次打开\n");        }        @Override        public void windowClosing(WindowEvent e) {            // TODO Auto-generated method stub            tArea.append("关闭窗口\n");            System.exit(0);        }        @Override        public void windowClosed(WindowEvent e) {            // TODO Auto-generated method stub            System.out.println("窗口被关闭");        }        @Override        public void windowIconified(WindowEvent e) {            // TODO Auto-generated method stub            tArea.append("窗口最小化\n");        }        @Override        public void windowDeiconified(WindowEvent e) {            // TODO Auto-generated method stub            tArea.append("窗口恢复\n");        }        @Override        public void windowActivated(WindowEvent e) {            // TODO Auto-generated method stub            tArea.append("窗口被激活\n");        }        @Override        public void windowDeactivated(WindowEvent e) {            // TODO Auto-generated method stub            tArea.append("窗口失去焦点\n");        }    }    public static void main(String[] args) {        new WindowListenerTest().init();    }}

事件适配器：

事件适配器是监听器接口的空实现–事件适配器实现了监听器接口，并为该接口里的每个方法都提供了实现，这种实现是一种空实现。
监听器接口和事件适配器对应表

监听器接口 事件适配器 ContainerListener ContainerAdapter FocusListener FocusAdapter ComponentListener ComponentAdapter KeyListener KeyAdapter MouseListener MouseAdapter MousMotionListener MouseMotionAdapter WindowListener WindowAdapter

实现事件监听器有如下几种形式：

1.内部类形式：将事件监听器类定义成当前类的内部类。
2.外部类形式：将事件监听器类定义成一个外部类。
3.类本身作为事件监听器类：让当前类本身实现监听器接口或继承事件适配器。
4.匿名内部类形式：使用匿名内部类创建事件监听器对象。

内部类形式：

package javaAWT;import java.awt.BorderLayout;import java.awt.Frame;import java.awt.Image;import java.awt.TextArea;import java.awt.Toolkit;import java.awt.event.WindowAdapter;import java.awt.event.WindowEvent;import javax.swing.ImageIcon;public class WindowAdapterTest {    private Frame frame = new Frame("WindowAdapterTest");    private TextArea textArea = new TextArea(6, 40);    private ImageIcon imageIcon = new ImageIcon();    public void init() {        frame.addWindowListener(new MyAdapterListener());        frame.add(textArea);        Image image = Toolkit.getDefaultToolkit().getImage("./123.jpg");        frame.setIconImage(image);        frame.pack();        frame.setVisible(true);    }    class MyAdapterListener extends WindowAdapter {        @Override        public void windowClosed(WindowEvent e) {            // TODO Auto-generated method stub            //super.windowClosed(e);            System.out.println("Closed window");            System.exit(0);        }    }    public static void main(String[] args) {        new WindowAdapterTest().init();    }}

外部类形式：

外部类监听器

package javaAWT;import java.awt.TextField;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;public class MailerListener implements ActionListener {    private TextField mailAddress;    public MailerListener(TextField mailAddress) {        // TODO Auto-generated constructor stub        this.mailAddress = mailAddress;    }    public void setMailAddress(TextField mailAddress) {        this.mailAddress = mailAddress;    }    @Override    public void actionPerformed(ActionEvent e) {        // TODO Auto-generated method stub        System.out.println("goto "+mailAddress.getText() + " send eMail");    }}

使用外部监听器

package javaAWT;import java.awt.BorderLayout;import java.awt.Button;import java.awt.Frame;import java.awt.TextField;import org.omg.CORBA.PRIVATE_MEMBER;public class SendMailer {    private Frame frame = new Frame("SendMailer");    private TextField tField = new TextField(40);    private Button send = new Button("Send");    public void init() {        send.addActionListener(new MailerListener(tField));        frame.add(tField);        frame.add(send, BorderLayout.SOUTH);        frame.pack();        frame.setVisible(true);    }    public static void main(String[] args) {        new SendMailer().init();    }}

类本身作为事件监听器类:

GUI类通过继承事件适配器方式（extends XxxAdapter）,可以只实现需要的监听器事件处理方法
。

package javaAWT;import java.awt.Frame;import java.awt.TextArea;import java.awt.TextField;import java.awt.event.WindowAdapter;import java.awt.event.WindowEvent;import org.omg.CosNaming.NamingContextExtPackage.AddressHelper;public class SimpleEventHandler extends WindowAdapter {    private Frame frame = new Frame("WindowAdapter");    private TextArea tArea = new TextArea(6, 40);    public void init() {        //将该类的默认对象作为事件监听对象        frame.addWindowListener(this);        frame.add(tArea);        frame.pack();        frame.setVisible(true);    }    // GUI 界面类直接包含事件处理器方法    @Override    public void windowClosing(WindowEvent e) {        // TODO Auto-generated method stub        super.windowClosing(e);        System.out.println("Window closed");        System.exit(0);    }    public static void main(String[] args) {    }}

GUI类通过实现事件监听器方式（ implements XxxListener），需要实现监听器的所有事件处理方法。

package javaAWT;import java.awt.Frame;import java.awt.TextArea;import java.awt.event.WindowEvent;import java.awt.event.WindowListener;import javax.swing.text.TabableView;public class SimpleEventHandlerB implements WindowListener {    private Frame f = new Frame("WindowListener");    private TextArea ta = new TextArea(10, 50);    public void init() {        f.addWindowListener(this);        f.add(ta);        f.pack();        f.setVisible(true);    }    @Override    public void windowOpened(WindowEvent e) {        // TODO Auto-generated method stub        ta.append("windowOpened"+"\n");    }    @Override    public void windowClosing(WindowEvent e) {        // TODO Auto-generated method stub        ta.append("windowClosing"+"\n");        System.exit(0);    }    @Override    public void windowClosed(WindowEvent e) {        // TODO Auto-generated method stub        ta.append("windowClosed"+"\n");    }    @Override    public void windowIconified(WindowEvent e) {        // TODO Auto-generated method stub        ta.append("windowIconified"+"\n");    }    @Override    public void windowDeiconified(WindowEvent e) {        // TODO Auto-generated method stub        ta.append("windowDeiconified"+"\n");    }    @Override    public void windowActivated(WindowEvent e) {        // TODO Auto-generated method stub        ta.append("windowActivated"+"\n");    }    @Override    public void windowDeactivated(WindowEvent e) {        // TODO Auto-generated method stub        ta.append("windowDeactivated"+"\n");    }    public static void main(String[] args) {        new SimpleEventHandlerB().init();    }}

匿名内部类形式:

匿名实现XxxxAdapter对象

package javaAWT;import java.awt.Frame;import java.awt.TextArea;import java.awt.event.MouseAdapter;import java.awt.event.MouseEvent;import java.awt.event.MouseListener;import java.awt.event.WindowAdapter;import java.awt.event.WindowEvent;public class AnonymousEventHandler {    private Frame frame = new Frame("AnonymousEventHandler");    private TextArea textArea = new TextArea(5, 20);    public void init() {        frame.addWindowListener(new WindowAdapter() {            @Override            public void windowClosing(WindowEvent e) {                // TODO Auto-generated method stub                super.windowClosing(e);                System.exit(0);            }        });        frame.add(textArea);        frame.pack();        frame.setVisible(true);    }    public static void main(String[] args) {        new AnonymousEventHandler().init();    }}

匿名实现XxxListener对象

package javaAWT;import java.awt.Frame;import java.awt.TextArea;import java.awt.event.WindowEvent;import java.awt.event.WindowListener;public class AnonymousEventHandlerB {    private Frame frame = new Frame("AnonymousEventHandlerB");    private TextArea textArea = new TextArea(5, 50);    public void init() {        frame.addWindowListener(new WindowListener() {            @Override            public void windowOpened(WindowEvent e) {                // TODO Auto-generated method stub            }            @Override            public void windowIconified(WindowEvent e) {                // TODO Auto-generated method stub            }            @Override            public void windowDeiconified(WindowEvent e) {                // TODO Auto-generated method stub            }            @Override            public void windowDeactivated(WindowEvent e) {                // TODO Auto-generated method stub            }            @Override            public void windowClosing(WindowEvent e) {                // TODO Auto-generated method stub                System.exit(0);            }            @Override            public void windowClosed(WindowEvent e) {                // TODO Auto-generated method stub            }            @Override            public void windowActivated(WindowEvent e) {                // TODO Auto-generated method stub            }        });        frame.add(textArea);        frame.pack();        frame.setVisible(true);    }    public static void main(String[] args) {        new AnonymousEventHandlerB().init();    }}