java GUI之事件处理

常见事件及相应事件源类型

事件源	用户操作	事件
JButton	点击按钮	ActionEvent
JTextField	在文本域按回车键	ActionEvent
JCheckBox	点击复选框	ActionEvent,  ItemEvent
JRadioButton	点击单选按钮	ActionEvent,  ItemEvent
JComBox	选定选项	ActionEvent,  ItemEvent
JList	选定选项	ListSelectionEvent
JMenuItem	选定菜单项	ActionEvent,  ItemEvent
JSlider	滑动滑块	ChangeEvent
Window	窗口打开,关闭等	WindowEvent
Component	点击或移动鼠标	MouseEvent
Component	按下或释放键盘上的键	KeyEvent
Container	在容器中添加或删除组件	ContainerEvent
Component	组件获得或失去焦点	FocusEvent
Component	组件移动,改变大小	ComponentEvent
JScrollBar	移动滚动条	AdjustmentEvent

java事件处理机制使用的是事件委托处理模型.事件监听器并不会自动接收某个组件触发的事件,要想监听器接收某个组件触发的某种事件,

就必须在该事件源中注册它(因此,程序可以有选择的忽略事件).所谓注册就是调用事件源提供的注册方法来声明某个对象是该事件源的监听器.

java语言中每种类型的事件定义了相应的监听器接口和注册方法.

一般来说,XXX事件的监听器接口是XXXListener,注册方法是addXXXListener.

部分常见的监听器接口

事件	监听器接口及注册方法	监听器方法
ActionEvent	ActionListener addActionListener	actionPerformed(ActionEvent e)
AdjustmentEvent	AdjustmentListener addAdjustmentListener()	adjustValueChanged(AdjustmentEvent e)
ComponentEvent	ComponentListener addComponentListener()	componentResized(ComponentEvent e) componentMoved(ComponentEvent e) componentShown(ComponentEvent e) componentHidden(ComponentEvent e)
ContainerEvent	ContainerEventListener addContainerEventListener()	componentAdded(ContainerEvent e) componentRemoved(ContainerEvent e)
FocusEvent	FocusListener addFocusListener()	focusGained(FocusEvent e) focusLost(FocusEvent e)
ItemEvent	ItemListener addItemListener()	itemStateChanged(ItemEvent e)
KeyEvent	KeyListener addKeyListener()	keyTyped(KeyEvent e) keyPressed(KeyEvent e) keyReleased(KeyEvent e)
MouseEvent	MouseListener addMouseListener()	mouseClicked(MouseEvent e) mousePressed(MouseEvent e) mouseReleased(MouseEvent e) mouseEntered(MouseEvent e) mouseExited(MouseEvent e)
MouseEvent	MouseMotionListener MouseMotionListener()	mouseDragged(MouseEvent e) mouseMoved(MouseEvent e)
TextEvent	TextListener addTextListener()	textValueChanged(TextEvent e)
WindowEvent	WindowListener addWindowListener()	stateChanged(ChangeEvent e)
ListSelectionEvent	ListSelectionListener addListSelectionListener()	valueChanged(ListSelectionEvent e)

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;


public class JButtonEvent extends JFrame implements ActionListener{
    public JButtonEvent(){
        JButton button=new JButton("按钮");
        button.addActionListener(this); //注册
        add(button);
    }
    public static void main(String[] args) {
        JButtonEvent frame=new JButtonEvent();
        frame.setTitle("演示动作事件处理");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500,300);
        frame.setVisible(true);
    }
    @Override
    public void actionPerformed(ActionEvent e) { //实现监听器接口中的方法
        System.out.println(((JButton)e.getSource()).getText());
    }    
}

运行结果

这种编程方式有许多不足,如可读性,重用性不佳等.现在比较流行使用内部类,特别是匿名内部类来实现监听类接口.

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;

public class JButtonEvent1 extends JFrame {
    public JButtonEvent1(){
        JButton button=new JButton("测试按钮");
        button.addActionListener(new ActionListener() {//匿名内部类
            
            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println(((JButton)e.getSource()).getText());
            }
        });
        add(button);
    }
    public static void main(String[] args) {
        JButtonEvent1 frame=new JButtonEvent1();
        frame.setTitle("演示动作事件处理");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500,300);
        frame.setVisible(true);
    }
}