java压缩图片【转】

   在我们浏览网页的时候，我们呢时常见到这样的效果，点击小图见大图，这里用到的技术便是图片压缩技术，是两张图片，不过是名字一样，在java中，同样可以实现图片的压缩处理，在网上好像找不到拿来就能用的，下面的这个可以用，但是有一些限制，只能压缩一些特定的图片文件，jpg，png，gif（非动画），大家可以研究下代码，根据代码自己去扩展合适的压缩类型，实际中，这些已经差不多可以运用了，下面是代码和在junit单元测试实例

 

package com.sport.utils;  
  
import java.awt.Color;  
import java.awt.Component;  
import java.awt.Graphics;  
import java.awt.Graphics2D;  
import java.awt.Image;  
import java.awt.MediaTracker;  
import java.awt.Toolkit;  
import java.awt.image.BufferedImage;  
import java.awt.image.ConvolveOp;  
import java.awt.image.Kernel;  
import java.io.ByteArrayOutputStream;  
import java.io.File;  
import java.io.FileInputStream;  
import java.io.FileOutputStream;  
import java.io.IOException;  
import java.io.OutputStream;  
  
import javax.imageio.ImageIO;  
import javax.swing.ImageIcon;  
  
import com.sun.image.codec.jpeg.JPEGCodec;  
import com.sun.image.codec.jpeg.JPEGEncodeParam;  
import com.sun.image.codec.jpeg.JPEGImageEncoder;  
  
/** 
 * 图像压缩工具 
 * @author  
 * 
 */  
public class ImageSizer {  
    public static final MediaTracker tracker = new MediaTracker(new Component() {  
        private static final long serialVersionUID = 1234162663955668507L;}   
    );  
    /** 
     * @param originalFile 原图像 
     * @param resizedFile 压缩后的图像 
     * @param width 图像宽 
     * @param format 图片格式 jpg, png, gif(非动画) 
     * @throws IOException 
     */  
    public static void resize(File originalFile, File resizedFile, int width, String format) throws IOException {  
        if(format!=null && "gif".equals(format.toLowerCase())){  
            resize(originalFile, resizedFile, width, 1);  
            return;  
        }  
        FileInputStream fis = new FileInputStream(originalFile);  
        ByteArrayOutputStream byteStream = new ByteArrayOutputStream();  
        int readLength = -1;  
        int bufferSize = 1024;  
        byte bytes[] = new byte[bufferSize];  
        while ((readLength = fis.read(bytes, 0, bufferSize)) != -1) {  
            byteStream.write(bytes, 0, readLength);  
        }  
        byte[] in = byteStream.toByteArray();  
        fis.close();  
        byteStream.close();  
          
        Image inputImage = Toolkit.getDefaultToolkit().createImage( in );  
        waitForImage( inputImage );  
        int imageWidth = inputImage.getWidth( null );  
        if ( imageWidth < 1 )   
           throw new IllegalArgumentException( "image width " + imageWidth + " is out of range" );  
        int imageHeight = inputImage.getHeight( null );  
        if ( imageHeight < 1 )   
           throw new IllegalArgumentException( "image height " + imageHeight + " is out of range" );  
          
        // Create output image.  
        int height = -1;  
        double scaleW = (double) imageWidth / (double) width;  
        double scaleY = (double) imageHeight / (double) height;  
        if (scaleW >= 0 && scaleY >=0) {  
            if (scaleW > scaleY) {  
                height = -1;  
            } else {  
                width = -1;  
            }  
        }  
        Image outputImage = inputImage.getScaledInstance( width, height, java.awt.Image.SCALE_DEFAULT);  
        checkImage( outputImage );          
        encode(new FileOutputStream(resizedFile), outputImage, format);          
    }      
  
    /** Checks the given image for valid width and height. */  
    private static void checkImage( Image image ) {  
       waitForImage( image );  
       int imageWidth = image.getWidth( null );  
       if ( imageWidth < 1 )   
          throw new IllegalArgumentException( "image width " + imageWidth + " is out of range" );  
       int imageHeight = image.getHeight( null );  
       if ( imageHeight < 1 )   
          throw new IllegalArgumentException( "image height " + imageHeight + " is out of range" );  
    }  
  
    /** Waits for given image to load. Use before querying image height/width/colors. */  
    private static void waitForImage( Image image ) {  
       try {  
          tracker.addImage( image, 0 );  
          tracker.waitForID( 0 );  
          tracker.removeImage(image, 0);  
       } catch( InterruptedException e ) { e.printStackTrace(); }  
    }   
  
    /** Encodes the given image at the given quality to the output stream. */  
    private static void encode( OutputStream outputStream, Image outputImage, String format )   
       throws java.io.IOException {  
       int outputWidth  = outputImage.getWidth( null );  
       if ( outputWidth < 1 )   
          throw new IllegalArgumentException( "output image width " + outputWidth + " is out of range" );  
       int outputHeight = outputImage.getHeight( null );  
       if ( outputHeight < 1 )   
          throw new IllegalArgumentException( "output image height " + outputHeight + " is out of range" );  
  
       // Get a buffered image from the image.  
       BufferedImage bi = new BufferedImage( outputWidth, outputHeight,  
          BufferedImage.TYPE_INT_RGB );                                                     
       Graphics2D biContext = bi.createGraphics();  
       biContext.drawImage( outputImage, 0, 0, null );  
       ImageIO.write(bi, format, outputStream);  
       System.out.println("----the end ------");  
       outputStream.flush();    
       outputStream.close();  
    }   
      
    /** 
     * 缩放gif图片 
     * @param originalFile 原图片 
     * @param resizedFile 缩放后的图片 
     * @param newWidth 宽度 
     * @param quality 缩放比例 (等比例) 
     * @throws IOException 
     */  
    private static void resize(File originalFile, File resizedFile, int newWidth, float quality) throws IOException {  
        if (quality < 0 || quality > 1) {  
            throw new IllegalArgumentException("Quality has to be between 0 and 1");  
        }   
        ImageIcon ii = new ImageIcon(originalFile.getCanonicalPath());  
        Image i = ii.getImage();  
        Image resizedImage = null;   
        int iWidth = i.getWidth(null);  
        int iHeight = i.getHeight(null);   
        if (iWidth > iHeight) {  
            resizedImage = i.getScaledInstance(newWidth, (newWidth * iHeight) / iWidth, Image.SCALE_SMOOTH);  
        } else {  
            resizedImage = i.getScaledInstance((newWidth * iWidth) / iHeight, newWidth, Image.SCALE_SMOOTH);  
        }   
        // This code ensures that all the pixels in the image are loaded.  
        Image temp = new ImageIcon(resizedImage).getImage();   
        // Create the buffered image.  
        BufferedImage bufferedImage = new BufferedImage(temp.getWidth(null), temp.getHeight(null),  
                                                        BufferedImage.TYPE_INT_RGB);   
        // Copy image to buffered image.  
        Graphics g = bufferedImage.createGraphics();   
        // Clear background and paint the image.  
        g.setColor(Color.white);  
        g.fillRect(0, 0, temp.getWidth(null), temp.getHeight(null));  
        g.drawImage(temp, 0, 0, null);  
        g.dispose();   
        // Soften.  
        float softenFactor = 0.05f;  
        float[] softenArray = {0, softenFactor, 0, softenFactor, 1-(softenFactor*4), softenFactor, 0, softenFactor, 0};  
        Kernel kernel = new Kernel(3, 3, softenArray);  
        ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);  
        bufferedImage = cOp.filter(bufferedImage, null);   
        // Write the jpeg to a file.  
        FileOutputStream out = new FileOutputStream(resizedFile);          
        // Encodes image as a JPEG data stream  
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);   
        JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bufferedImage);   
        param.setQuality(quality, true);   
        encoder.setJPEGEncodeParam(param);  
        encoder.encode(bufferedImage);  
    }  
}  

 

单元测试，看如何使用

 

@Test  
public void imagetest(){  
      
    try {  
        ImageSizer.resize(new File("f:\\image\\363.jpg"), new File("f:\\image\\testabc.jpg"), 100, "jpg");  
    } catch (IOException e) {  
        e.printStackTrace();  
    }  
      
}  

 

原文地址：http://zhuhichn.iteye.com/blog/509343