JAVA自动截取全屏代码(转载于http://www.sunxin.org/article/381.htmls)

package com.xiangzi.capture;

import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.net.URL;

import javax.imageio.ImageIO;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGEncodeParam;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

@SuppressWarnings("restriction")
public class GrapScreem {

public GrapScreem() {

}

public static void main(String[] args) {

// snatchPicture("http://img5.pcpop.com/ProductImages/Original/0/588/000588468.jpg",

// "C://7755p2c");

// 截取当前屏幕保存为 c 盘根目录下的 screen.jpg 图片

snatchScreen ( "c://screen.jpg" );

// 根据 c 盘根目录下的 screen.jpg 图片，创建一个宽 128 ，高 102 的缩略图 screenSmall.jpg 并保存在 c 盘根目录下面

createThumbnail ( "c://screen.jpg" , 128, 102, 10, "c://screenSmall.jpg" );

System. out .println( "successful" );

}

/**

* 抓取当前屏幕 create date:2008- 7- 28 author:Administrator

*

* @param path

* @throws Exception

*/

public static void snatchScreen(String path) {

Robot robot;

try {

robot = new Robot();

Dimension d = Toolkit.getDefaultToolkit ().getScreenSize();

Rectangle rect = new Rectangle(0, 0, d. width , d. height );

BufferedImage image = robot.createScreenCapture(rect);

ImageIO.write (image, "jpg" , new File(path));

} catch (Exception e) {

System. out .println( "Failed to snatch screen ... " );

e.printStackTrace();

}

}

/**

* java 创建图片的缩略图 create date:2009- 5- 27 author:Administrator

*

* @param filename

*             源图片

* @param thumbWidth

*             缩略图宽

* @param thumbHeight

*             缩略图高

* @param quality

*             图片像素

* @param outFilename

*             缩略图文件名

*

*/

private static void createThumbnail(String filename, int thumbWidth,

int thumbHeight, int quality, String outFilename) {

// load image from filename

Image image = Toolkit.getDefaultToolkit ().getImage(filename);

MediaTracker mediaTracker = new MediaTracker( new Container());

mediaTracker.addImage(image, 0);

try {

mediaTracker.waitForID(0);

// use this to test for errors at this point:

// System.out.println(mediaTracker.isErrorAny());

// determine thumbnail size from WIDTH and HEIGHT

double thumbRatio = ( double ) thumbWidth / ( double ) thumbHeight;

int imageWidth = image.getWidth( null );

int imageHeight = image.getHeight( null );

double imageRatio = ( double ) imageWidth / ( double ) imageHeight;

if (thumbRatio < imageRatio) {

thumbHeight = ( int ) (thumbWidth / imageRatio);

} else {

thumbWidth = ( int ) (thumbHeight * imageRatio);

}

// draw original image to thumbnail image object and

// scale it to the new size on-the-fly

BufferedImage thumbImage = new BufferedImage(thumbWidth,

thumbHeight, BufferedImage. TYPE_INT_RGB );

Graphics2D graphics2D = thumbImage.createGraphics();

graphics2D.setRenderingHint(RenderingHints. KEY_INTERPOLATION ,

RenderingHints. VALUE_INTERPOLATION_BILINEAR );

graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null );

// save thumbnail image to outFilename

BufferedOutputStream out = new BufferedOutputStream(

new FileOutputStream(outFilename));

JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder (out);

JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(thumbImage);

quality = Math.max (0, Math.min (quality, 100));

param.setQuality(( float ) quality / 100.0f, false );

encoder.setJPEGEncodeParam(param);

encoder.encode(thumbImage);

out.close();

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

/**

* 实现从网站下载图片 create date:2008- 7- 28 author:Administrator

*

* @param urlPath

* @param picPathName

*/

public static void snatchPicture(String urlPath, String picPathName) {

try {

URL url = new URL(urlPath);

BufferedInputStream bis = new BufferedInputStream(url.openStream());

byte [] bytes = new byte [2048];

OutputStream bos = new FileOutputStream( new File(picPathName));

int len;

while ((len = bis.read(bytes)) > 0) {

bos.write(bytes, 0, len);

}

bis.close();

bos.flush();

bos.close();

} catch (Exception e) {

System. out .println( " 抓取图片失败 ... " );

e.printStackTrace();

}

}

}

在Eclipse中处理图片，需要引入两个包：
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
报错:
Access restriction: The type JPEGImageEncoder is not accessible due to restriction on required library C:/Java/jre1.6.0_07/lib/rt.jar

此时解决办法：
Eclipse默认把这些受访问限制的API设成了ERROR。只要把Windows-Preferences-Java-Complicer-Errors/Warnings里面的Deprecated and restricted API中的Forbidden references(access rules)选为Warning就可以编译通过。