《JAVA异常处理》

来源：互联网发布：python简明中文教程编辑：程序博客网时间：2024/06/06 20:19

1.用java.awt.*;包，一般还要用java.swing.*;做GUI.

2.事件侦听器与侦听接口：

步骤：

（1）继承implemnts ActionListener类

（2）实现ActionListener接口的事件处理方法actionPerformed(ActionEvente)

（3）注册事件侦听器，对象.addactrionListener(侦听器名);

3. 实例：（点击按钮设置屏背景颜色的例子）

import java.awt.*;

import java.awt.event.*;

class ColorAction implements ActionListener{//事件侦听器类

privateActionEventFrame frame;//用主类对象作为变量,方便两类之间联系

private Colorbackgroundcolor;

publicColorAction(ActionEventFrame aef, Color c) {//带2个参数的构造方法

frame =aef;

backgroundcolor= c;

}

publicvoid actionPerformed(ActionEvent e) {//实现接口方法

frame.setBackground(backgroundcolor);

}

public class ActionEventFrame extends Frame {

ActionEventFrame(){

Panelpanel = new Panel();

//创建三个事件源

Buttonredbutton = new Button("红色");

Buttongreenbutton = new Button("绿色");

Buttonbluebutton = new Button("蓝色");

panel.add(redbutton);

panel.add(greenbutton);

panel.add(bluebutton);

add(panel,"South");

//注册事件侦听器:同一个类的三个不同对象

redbutton.addActionListener(newColorAction(this, Color.red));

greenbutton.addActionListener(newColorAction(this, Color.green));

bluebutton.addActionListener(newColorAction(this, Color.blue));

}

public staticvoid main(String argc[]) {

ActionEventFramemyframe = new ActionEventFrame();

myframe.setTitle("ActionEvent事件");

myframe.setSize(200,150);

myframe.setVisible(true);

}

1. 窗口状态WindowEvent事件

import java.awt.*;

import java.awt.event.*;

public class WinEventTest extends Frame implementsWindowListener{

Frame owner;

Dialog dig;

public WinEventTest( ){//构造方法

setTitle("窗口事件处理");

addWindowListener(this);//注册监听者

this.owner=this;

setSize(200,200);

setVisible(true);

}

public void windowClosing(WindowEvent e){//重写窗口关闭方法

dig=new Dialog(owner,"确认退出",true);

Panel p=new Panel();

Button yes=new Button("是");

Button no=new Button("否");

p.add(yes);

p.add(no);

yes.addActionListener(new ActionListener(){//内部类形式注册及重写事件处理方法

public void actionPerformed(ActionEvent e){

owner.dispose();

}

});

no.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e){

dig.dispose();

}

});

dig.add(new Label("想要退出吗？"));

dig.add(p,"South");

dig.setSize(200,100);

dig.setVisible(true);

}

//实现WindowListener接口的所有方法

public void windowClosed(WindowEvent e){}

public void windowDeactivated(WindowEvent e){}

public void windowActivated(WindowEvent e){}

public void windowIconified(WindowEvent e){}

public void windowDeiconified(WindowEvent e){}

public void windowOpened(WindowEvent e){}

public static void main(String[] args){

WinEventTest obj=new WinEventTest();

}

2. 适配器（使其不用实现接口的所有方法，进行简化）

（上题更改后）

import java.awt.*;

import java.awt.event.*;

public class WinAdapterTest extends Frame {

Frame owner;

Dialog dig;

public WinAdapterTest(){

setTitle("窗口事件处理");

this.owner=this;

setSize(200,200);

setVisible(true);

WindowListener winHandler=new WindowAdapter(){//内部类

public void windowClosing(WindowEvent e){

dig=new Dialog(owner,"确认退出",true);

Panel p=new Panel();

Button yes=new Button("是");

Button no=new Button("否");

p.add(yes);

p.add(no);

yes.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e){

owner.dispose();

}

});

no.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e){

dig.dispose();

}

} );

dig.add(new Label("想要退出吗？"));

dig.add(p,"South");

dig.setSize(200,100);

dig.setVisible(true);

}

};

addWindowListener(winHandler);//注册监听者

}

public static void main(String[] args){

WinAdapterTest obj=newWinAdapterTest();

}

3. 事件侦听器的几种方式

1. 鼠标事件处理

（实例）

import java.awt.*;

import java.awt.event.*;

public class MouseEventTest extends Frame {

Label mouseInfo1, mouseInfo2;

public MouseEventTest() {

super("Mouse移动处理");

mouseInfo1 = newLabel("");

mouseInfo1.setBackground(Color.YELLOW);

mouseInfo2 = newLabel("");

mouseInfo2.setBackground(Color.YELLOW);

add(mouseInfo1,"North");

add(mouseInfo2,"South");

addMouseMotionListener(newMouseMotionAdapter() {

public voidmouseMoved(MouseEvent e) {

mouseInfo1.setText(e.getX()+ " " + e.getY());//获取坐标

}

});

addMouseListener(newMouseAdapter() {

public voidmouseEntered(MouseEvent e) {//鼠标进入方法

mouseInfo2.setText("Enter");

}

public voidmouseExited(MouseEvent e) {//鼠标离开方法

mouseInfo2.setText("Exit");

}

public voidmousePressed(MouseEvent e) {//鼠标按下方法

if(e.getButton() == e.BUTTON1)

mouseInfo2.setText("LeftButton");

else if(e.getButton() == e.BUTTON2)

mouseInfo2.setText("MiddleButton");

else if(e.getButton() == e.BUTTON3)

mouseInfo2.setText("RightButton");

}

});

}

public static void main(String[]args) {

final MouseEventTest obj = newMouseEventTest();

obj.setSize(300, 200);

obj.setVisible(true);

obj.addWindowListener(newWindowAdapter() {

public voidwindowClosing(WindowEvent e) {

obj.dispose();

}

});

}

2. 键盘事件处理

import java.awt.*;

import java.awt.event.*;

public class KeyEventTest extends Frame {

Button man;

publicKeyEventTest() {

super("活用Key事件");

setLayout(null);

setSize(300,150);

man = newButton("按下键盘的箭头键移动试试");

man.setBounds(20,50, 150, 40);

man.setBackground(Color.BLUE);

man.setForeground(Color.WHITE);

add(man);

man.addKeyListener(newKeyAdapter() {

publicvoid keyPressed(KeyEvent e) {

Stringdirection = e.getKeyText(e.getKeyCode());

intx = man.getX();

inty = man.getY();

if(direction.equals("Right"))

x+= 10;

elseif (direction.equals("Left"))

x-= 10;

elseif (direction.equals("Down"))

y+= 10;

elseif (direction.equals("Up"))

y-= 10;

man.setLocation(x,y);

}

});

}

public staticvoid main(String[] args) {

finalKeyEventTest obj = new KeyEventTest();

obj.setVisible(true);

obj.addWindowListener(newWindowAdapter() {

publicvoid windowClosing(WindowEvent e) {

obj.dispose();

}

});

}

n char getKeyChar(): 返回按键表示的字符

例如：直接按“a”,返回字符a，若按“Shift+a”，则返回字符A，

n int getKeyCode()：返回整数 keyCode(键盘按键的编号)

无论是按”a”，还是”Shift+a”，均返回65。KeyEvent类定义许多常量来表示键码值，例如：VK_F1~VK_F12, VK_LEFT,VK_KP_UP,VK_HOME,VK_SHIFT,VK_ALT,,… 具体见API文档

n String getKeyText(intkeyCode) ：返回keyCode所对应的String，即取得按键表示的文字。如“HOME”、“F1”或“A”

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