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java动画——键盘事件
摘要: java动画——键盘事件
// 程序：人物走动
// 范例文件：HandleKeyboardEvent.java
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class HandleKeyboardEvent extends Applet
implements KeyListener
{
int ImageWidth,ImageHeight,ImageX,ImageY,AppletWidth,
AppletHeight,key;
int sx;
Image character,OffScreen;
Thread newThread;
Graphics drawOffScreen;
MediaTracker MT;
public void init()
{
addKeyListener(this); //注册事件处理方法
setBackground(Color.white); //设定背景颜色
AppletWidth = getSize().width; //取得Applet的高度
AppletHeight = getSize().height; //取得Applet的宽度
sx = 0;
//取得图像
MT = new MediaTracker(this);
for(int i=0;i<5;i++)
{
character = getImage(getDocumentBase(),"Images/character.gif");
MT.addImage(character,0);
}
try
{
showStatus("图像加载中(Loading Images)...");
MT.waitForAll();
}
catch(InterruptedException E){ } //没有进行异常处理
//建立次画面
OffScreen = createImage(AppletWidth,AppletHeight);
drawOffScreen = OffScreen.getGraphics();
ImageWidth = character.getWidth(this) / 3; //图像的高度
ImageHeight = character.getHeight(this) / 4; //图像的宽度
ImageX = (AppletWidth - ImageWidth) / 3; //图像的X坐标
ImageY = (AppletHeight - ImageHeight) / 3; //图像的Y坐标
drawOffScreen.clearRect(0,0,AppletWidth,AppletHeight);
drawOffScreen.drawImage(character,ImageX,ImageY,ImageX+72,ImageY+93,
0, 0, 24, 31,this);
}
public void paint(Graphics g)
{
//将次画面贴到主画面中
g.drawImage(OffScreen,0,0,this);
}
public void update(Graphics g) //update()方法
{
paint(g); //只单纯调用paint()方法
}
//=====实现KeyListener界面==========================================
public void keyTyped(KeyEvent e) { }
public void keyPressed(KeyEvent e)
{
key = e.getKeyCode();
// 清除次画面
drawOffScreen.clearRect(0,0,AppletWidth,AppletHeight);
if(key == KeyEvent.VK_RIGHT)
{
drawOffScreen.drawImage(character,ImageX,ImageY,ImageX+72,ImageY+93,
sx, 31, sx+24, 62,this);
repaint();
// 人物走动
ImageX += 2;
sx += 24;
if(sx > 48)
sx = 0;
}
else if(key == KeyEvent.VK_LEFT)
{
drawOffScreen.drawImage(character,ImageX,ImageY,ImageX+72,ImageY+93,
sx, 93, sx+24, 124,this);
repaint();
// 人物走动
ImageX -= 2;
sx += 24;
if(sx > 48)
sx = 0;
}
else if(key == KeyEvent.VK_UP)
{
drawOffScreen.drawImage(character,ImageX,ImageY,ImageX+72,ImageY+93,
sx, 0, sx+24, 31,this);
repaint();
// 人物走动
ImageY -= 2;
sx += 24;
if(sx > 48)
sx = 0;
}
else if(key == KeyEvent.VK_DOWN)
{
drawOffScreen.drawImage(character,ImageX,ImageY,ImageX+72,ImageY+93,
sx, 62, sx+24, 93,this);
repaint();
// 人物走动
ImageY += 2;
sx += 24;
if(sx > 48)
sx = 0;
}
}
public void keyReleased(KeyEvent e)
{
sx = 0;
}
}
对于事件处理首先要再定义类的开始部分继承相应的接口：
public class HandleKeyboardEvent extends Applet
implements KeyListener
然后再初始化阶段，注册处理事件：
public void init()
{
addKeyListener(this); //注册事件处理方法
最后在代码中添加事件处理函数：
public void keyTyped(KeyEvent e)
public void keyPressed(KeyEvent e)
public void keyReleased(KeyEvent e) 需要提醒的是，即使这是事件不用，也要列出来。