java压缩图片

java压缩图片(转自http://zhuhichn.iteye.com/blog/509343)

 

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);
font-size: 1em; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 38px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 10px; border-left-width: 1px; border-left-style: solid; border-left-color: #d1d7dc

• ImageSizer.rar (2.3 KB)
• 下载次数: 72

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• 2010-09-07 15:05
• 浏览 1063
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