总体思想：
1.前台网页用js得到裁剪图片的id及x,y，宽度和高度。
2.服务端根据id取出要裁剪的图片 。
3.根据这些参数来生成裁剪的图像。
后台代码如下：
package
com.wodexiangce;
import
java.awt.Rectangle;
import
java.awt.image.BufferedImage;
import
java.io.File;
import
java.io.FileInputStream;
import
java.io.IOException;
import
java.util.Iterator;
import
javax.imageio.ImageIO;
import
javax.imageio.ImageReadParam;
import
javax.imageio.ImageReader;
import
javax.imageio.stream.ImageInputStream;
/**
*//**
*
*
* @author <a href="mailto:lqinglong@yahoo.cn">qinglong.lu</a>
*
* 2008-3-21
*/
public
class OperateImage ...{
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//===源图片路径名称如:c:/1.jpg
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private String srcpath ;
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//===剪切图片存放路径名称.如:c:/2.jpg
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private String subpath ;
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//===剪切点x坐标
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private int x ;
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private int y ;???
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//===剪切点宽度
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private int width ;
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private int height ;
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public OperateImage()...{
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}?
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public OperateImage(int x,int y,int width,int height)...{
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this.x = x ;
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this.y = y ;
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this.width = width ;??
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this.height = height ;
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}
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/** *//**
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* 对图片裁剪，并把裁剪完蛋新图片保存 。
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*/
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public void cut() throws IOException...{
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FileInputStream is = null ;
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ImageInputStream iis =null ;
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try...{??
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//读取图片文件
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is = new FileInputStream(srcpath);
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/**//*
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* 返回包含所有当前已注册 ImageReader 的 Iterator，这些 ImageReader
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* 声称能够解码指定格式。 参数：formatName - 包含非正式格式名称 .
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*（例如 "jpeg" 或 "tiff"）等 。
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*/
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Iterator<ImageReader> it = ImageIO.getImageReadersByFormatName("jpg");?
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ImageReader reader = it.next();
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//获取图片流
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iis = ImageIO.createImageInputStream(is);
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/**//*
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* <p>iis:读取源.true:只向前搜索 </p>.将它标记为 ‘只向前搜索’。
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* 此设置意味着包含在输入源中的图像将只按顺序读取，可能允许 reader
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*? 避免缓存包含与以前已经读取的图像关联的数据的那些输入部分。
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*/
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reader.setInput(iis,true) ;
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/**//*
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* <p>描述如何对流进行解码的类<p>.用于指定如何在输入时从 Java Image I/O
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* 框架的上下文中的流转换一幅图像或一组图像。用于特定图像格式的插件
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* 将从其 ImageReader 实现的 getDefaultReadParam 方法中返回
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* ImageReadParam 的实例。?
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*/
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ImageReadParam param = reader.getDefaultReadParam();
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/**//*
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* 图片裁剪区域。Rectangle 指定了坐标空间中的一个区域，通过 Rectangle 对象
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* 的左上顶点的坐标（x，y）、宽度和高度可以定义这个区域。
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*/
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Rectangle rect = new Rectangle(x, y, width, height);
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//提供一个 BufferedImage，将其用作解码像素数据的目标。
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param.setSourceRegion(rect);
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/**//*
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* 使用所提供的 ImageReadParam 读取通过索引 imageIndex 指定的对象，并将
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* 它作为一个完整的 BufferedImage 返回。
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*/
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BufferedImage bi = reader.read(0,param);???????????????
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//保存新图片
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ImageIO.write(bi, "jpg", new File(subpath));????
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}
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finally...{
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if(is!=null)
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is.close() ;??????
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if(iis!=null)
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iis.close();?
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}
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}
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public int getHeight() ...{
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return height;
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}
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public void setHeight(int height) ...{
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this.height = height;
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}
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public String getSrcpath() ...{
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return srcpath;
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}
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public void setSrcpath(String srcpath) ...{
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this.srcpath = srcpath;
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}
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public String getSubpath() ...{
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return subpath;
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}
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public void setSubpath(String subpath) ...{
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this.subpath = subpath;
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}
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public int getWidth() ...{
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return width;
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}
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public void setWidth(int width) ...{
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this.width = width;
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}
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public int getX() ...{
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return x;
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}
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public void setX(int x) ...{
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this.x = x;
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}
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public int getY() ...{
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return y;
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}
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public void setY(int y) ...{
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this.y = y;
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}
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public static void main(String[] args)throws Exception...{
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String name = "d:/2005121210161588950.jpg";
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OperateImage o = new OperateImage(100,100,100,100);
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o.setSrcpath(name);?
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o.setSubpath("D:/2.jpg");
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o.cut() ;?
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}
}