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JPEG图片生成器实现过程
实现代码：
package jpeg;
import java.awt.*;
import java.util.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
import com.sun.image.codec.jpeg.*;
public class MakeJPEG extends Canvas implements MouseMotionListener,MouseListener,ActionListener{
private static final long serialVersionUID = 1L;
int x=-1,y=-1,橡皮擦通知=0,清除通知=0;
Vector v=null;
int n=1;
Graphics2D ggg;
BufferedImage image;Frame window;
Button 保存,调色板,橡皮,清除,画笔,获取屏幕,绘制图形;
Color 画笔颜色;
Panel pCenter,pSouth,pNorth;
public MakeJPEG(){
保存=new Button("将绘制的图形或屏幕保存为JPG文件");
获取屏幕=new Button("获取屏幕");
绘制图形=new Button("绘制图形");
调色板=new Button("打开调色板");
画笔=new Button("画笔");
橡皮=new Button("橡皮");
清除=new Button("清除");
调色板.addActionListener(this);
绘制图形.addActionListener(this);
保存.addActionListener(this);
画笔.addActionListener(this);
橡皮.addActionListener(this);
清除.addActionListener(this);
获取屏幕.addActionListener(this);
画笔颜色=new Color(0,0,0);
addMouseMotionListener(this);addMouseListener(this);
v=new Vector();
setBackground(Color.white);
image =new BufferedImage(400,400,BufferedImage.TYPE_INT_RGB);
ggg=image.createGraphics();
Rectangle2D rect= new Rectangle2D.Double(0,0,400,400);
ggg.setColor(getBackground());
ggg.fill(rect);
window=new Frame("JPEG图像生成器");
pCenter=new Panel();
pCenter.setLayout(null);
pCenter.add(this);
pCenter.setBackground(Color.gray);
this.setBounds(80,30,210,210);
window.add(pCenter,BorderLayout.CENTER);
pNorth=new Panel();
pNorth.add(保存);
pNorth.add(绘制图形);
pNorth.add(获取屏幕);
window.add(pNorth,BorderLayout.NORTH);
pSouth=new Panel();
pSouth.add(调色板);
pSouth.add(橡皮);
pSouth.add(清除);
pSouth.add(画笔);
window.add(pSouth, BorderLayout.SOUTH);
window.setVisible(true);
window. addWindowListener(new WindowAdapter() {
public void windowClosing( WindowEvent e) {
System.exit(0);}});
window. setBounds(100,80,390,380);
window.validate();}
public void paint(Graphics g) {
if(x!=-1&&y!=-1&&橡皮擦通知 ==0&&清除通知==0) {
g.setColor(画笔颜色);
n=v.size();
for(int i=0;i<n-1;i++) {
Point p1=(Point)v.elementAt(i);
Point p2=(Point)v.elementAt(i+1);
g.drawLine(p1.x,p1.y,p2.x,p2.y);
ggg.setColor(g.getColor());
ggg. drawLine(p1.x,p1.y,p2.x,p2.y);}}
else if(橡皮擦通知==1&&清除通知==0) {
g.setColor(getBackground());
g.fillRect(x-2,y-2,4,4);
ggg.setColor(getBackground());
ggg.fillRect(x-2,y-2,4,4);}
else if(清除通知== 1&&橡皮擦通知==0) {
g.setColor(getBackground());
g.fillRect(0,0,200,200);
ggg.setColor(getBackground());
ggg.fillRect(0,0,200,200);}
g.drawImage(image,0,0,200,200,this);}
public void mouseDragged(MouseEvent e) {
x=(int)e.getX();
y=(int)e.getY();
Point p=new Point(x,y);
v.addElement(p);
repaint();}
public void mouseMoved(MouseEvent e) {}
public void mousePressed(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {
v.removeAllElements();}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
public void mouseClicked(MouseEvent e) {}
public void update(Graphics g) {{
paint(g);}}
public void actionPerformed(ActionEvent e) {
if(e.getSource() ==橡皮) {
橡皮擦通知=1;
清除通知=0;}
else if(e.getSource()== 清除) {
橡皮擦通知=0;
清除通知=1;
repaint();}
else if(e. getSource()==画笔) {
橡皮擦通知=0;
清除通知=0;}
else if(e.getSource()==保存) {
FileDialog savedialog= new FileDialog(window,"保存图形到JPG格式",FileDialog.SAVE);
savedialog.setVisible(true);
if(savedialog.getFile() !=null) {
try {
String fileName =savedialog.getFile();
FileOutputStream out= new FileOutputStream(fileName);
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
JPEGEncodeParam param=encoder.getDefaultJPEGEncodeParam(image);
param.setQuality(1.0f,false);
encoder.setJPEGEncodeParam(param);
encoder.encode(image);
out.close();}catch(Exception EE) {}
}}
else if(e. getSource()== 获取屏幕) {
Robot robot= null;
try {
robot =new Robot();}catch(Exception er) {}
Rectangle screenRect =null;
int width= getToolkit().getScreenSize().width;
int height=getToolkit().getScreenSize().height;
screenRect=new Rectangle(0,0,width,height);
window.setVisible(false);
this.window.setVisible( false);
image=robot.createScreenCapture(screenRect);
window.setVisible(true);
repaint();}
else if(e.getSource()==调色板) {
Color tempColor =JColorChooser.showDialog(window,"调色板",画笔颜色);{
if(tempColor!=null) {
画笔颜色=tempColor;
画笔.setForeground(画笔颜色);}}}
else if(e.getSource()==绘制图形) {
window.dispose();
this.window.dispose();}}
//MakeJPEG canvas= new MakeJPEG();
public static void main(String args[]) {
new MakeJPEG();}}
