import java.awt.Image;  
import java.awt.Rectangle;  
import java.awt.geom.AffineTransform;  
import java.awt.image.AffineTransformOp;  
import java.awt.image.BufferedImage;  
import java.io.File;  
import java.io.FileInputStream;  
import java.io.IOException;  
import java.io.InputStream;  
import java.util.Iterator;

import javax.imageio.ImageIO;  
import javax.imageio.ImageReadParam;  
import javax.imageio.ImageReader;  
import javax.imageio.stream.ImageInputStream;  
 
public class ImageHelper {  
    public static void main(String[] args) throws Exception {
        try {
            ImageHelper.zoomImage("c:/test.jpg","c:\\7.png",400,400);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    /*
     * 根据尺寸图片居中裁剪
     */  
     public static void cutCenterImage(String src,String dest,int w,int h) throws IOException{   
         Iterator iterator = ImageIO.getImageReadersByFormatName("jpg");   
         ImageReader reader = (ImageReader)iterator.next();   
         InputStream in=new FileInputStream(src);  
         ImageInputStream iis = ImageIO.createImageInputStream(in);   
         reader.setInput(iis, true);   
         ImageReadParam param = reader.getDefaultReadParam();   
         int imageIndex = 0;   
         Rectangle rect = new Rectangle((reader.getWidth(imageIndex)-w)/2, (reader.getHeight(imageIndex)-h)/2, w, h);    
         param.setSourceRegion(rect);   
         BufferedImage bi = reader.read(0,param);     
         ImageIO.write(bi, "jpg", new File(dest));             
    
     }  
    /*
     * 图片裁剪二分之一
     */  
     public static void cutHalfImage(String src,String dest) throws IOException{   
         Iterator iterator = ImageIO.getImageReadersByFormatName("jpg");   
         ImageReader reader = (ImageReader)iterator.next();   
         InputStream in=new FileInputStream(src);  
         ImageInputStream iis = ImageIO.createImageInputStream(in);   
         reader.setInput(iis, true);   
         ImageReadParam param = reader.getDefaultReadParam();   
         int imageIndex = 0;   
         int width = reader.getWidth(imageIndex)/2;   
         int height = reader.getHeight(imageIndex)/2;   
         Rectangle rect = new Rectangle(width/2, height/2, width, height);   
         param.setSourceRegion(rect);   
         BufferedImage bi = reader.read(0,param);     
         ImageIO.write(bi, "jpg", new File(dest));     
     }  
    
     /**
      * 图片裁剪通用接口
      * @param src   
      * @param dest
      * @param x
      * @param y
      * @param w
      * @param h
      * @throws IOException
      */
    public static void cutImage(String src,String dest,int x,int y,int w,int h) throws IOException{   
           Iterator iterator = ImageIO.getImageReadersByFormatName("jpg");   
           ImageReader reader = (ImageReader)iterator.next();   
           InputStream in=new FileInputStream(src);  
           ImageInputStream iis = ImageIO.createImageInputStream(in);   
           reader.setInput(iis, true);   
           ImageReadParam param = reader.getDefaultReadParam();   
           Rectangle rect = new Rectangle(x, y, w,h);    
           param.setSourceRegion(rect);   
           BufferedImage bi = reader.read(0,param);     
           ImageIO.write(bi, "jpg", new File(dest));             
 
    }   
    
    /**
     * 图片缩放
     * @param src  image path
     * @param dest target　Ｐ
     * @param w
     * @param h
     * @throws Exception
     */
    public static void zoomImage(String src,String dest,int w,int h) throws Exception {  
        double wr=0,hr=0;  
        File srcFile = new File(src);  
        File destFile = new File(dest);  
        BufferedImage bufImg = ImageIO.read(srcFile);  
        Image Itemp = bufImg.getScaledInstance(w, h, bufImg.SCALE_SMOOTH);  
        wr=w*1.0/bufImg.getWidth();  
        hr=h*1.0 / bufImg.getHeight();  
        // 如果是低于400的话 就不操作
        if(wr>1){
            wr=1;
        }
        if(hr>1){
            hr=1;
        }
        AffineTransformOp ato = new AffineTransformOp(AffineTransform.getScaleInstance(wr, hr), null);  
        Itemp = ato.filter(bufImg, null);  
        try {  
            ImageIO.write((BufferedImage) Itemp,dest.substring(dest.lastIndexOf(".")+1), destFile);  
        } catch (Exception ex) {  
            ex.printStackTrace();  
        }  
    }  
}