Java实现图片压缩

package com.pb.util;

import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
 
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;
 
public class ImageCompressUtil {
    /**
     * 直接指定压缩后的宽高：
     * @param oldFile 要进行压缩的文件全路径
     * @param width 压缩后的宽度
     * @param height 压缩后的高度
     * @param quality 压缩质量，这个参数可以自己调节大小
     * @return 返回压缩后的文件的全路径
     */
    public static String zipImageFile(String oldFile, int width, int height, float quality) {
        if (oldFile == null) {
            return null;
        }
        String newImage = null;
        try {
            /**读取旧图片，获取旧图片的宽高 */
            File file = new File(oldFile);
            Image srcFile = ImageIO.read(file);
            //int w = srcFile.getWidth(null);
            //int h = srcFile.getHeight(null);
            //width = w/2;
            //height = h/2;
            /** 宽,高设定 */
            BufferedImage tag = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            tag.getGraphics().drawImage(srcFile, 0, 0, width, height, null);
            String filePrex = oldFile.substring(0, oldFile.indexOf('.'));
            /** 压缩后的文件名 */
            newImage = filePrex + "new" + oldFile.substring(filePrex.length());
            /** 压缩之后临时存放位置 */
            FileOutputStream out = new FileOutputStream(newImage);
            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
            JPEGEncodeParam jep = JPEGCodec.getDefaultJPEGEncodeParam(tag);
            /** 压缩质量 */
            jep.setQuality(quality, true);
            encoder.encode(tag, jep);
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return newImage;
    }

    /**
     * 等比例压缩算法：
     * 算法思想：根据压缩基数和压缩比来压缩原图，生产一张图片效果最接近原图的缩略图
     * @param srcURL 原图地址
     * @param deskURL 缩略图地址
     * @param comBase 压缩基数
     * @param scale 压缩限制(宽/高)比例  一般用1：
     * 当scale>=1,缩略图height=comBase,width按原图宽高比例;若scale<1,缩略图width=comBase,height按原图宽高比例
     * @throws Exception
     */
    public static void saveMinPhoto(String srcURL, String deskURL, double comBase,
            double scale) throws Exception {
        File srcFile = new java.io.File(srcURL);
        Image src = ImageIO.read(srcFile);
        int srcHeight = src.getHeight(null);
        int srcWidth = src.getWidth(null);
        int deskHeight = 0;// 缩略图高
        int deskWidth = 0;// 缩略图宽
        double srcScale = (double) srcHeight / srcWidth;
        /**缩略图宽高算法*/
        if ((double) srcHeight > comBase || (double) srcWidth > comBase) {
            if (srcScale >= scale || 1 / srcScale > scale) {
                if (srcScale >= scale) {
                    deskHeight = (int) comBase;
                    deskWidth = srcWidth * deskHeight / srcHeight;
                } else {
                    deskWidth = (int) comBase;
                    deskHeight = srcHeight * deskWidth / srcWidth;
                }
            } else {
                if ((double) srcHeight > comBase) {
                    deskHeight = (int) comBase;
                    deskWidth = srcWidth * deskHeight / srcHeight;
                } else {
                    deskWidth = (int) comBase;
                    deskHeight = srcHeight * deskWidth / srcWidth;
                }
            }
        } else {
            deskHeight = srcHeight;
            deskWidth = srcWidth;
        }
        BufferedImage tag = new BufferedImage(deskWidth, deskHeight, BufferedImage.TYPE_3BYTE_BGR);
        tag.getGraphics().drawImage(src, 0, 0, deskWidth, deskHeight, null); //绘制缩小后的图
        FileOutputStream deskImage = new FileOutputStream(deskURL); //输出到文件流
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(deskImage);
        encoder.encode(tag); //近JPEG编码
        deskImage.close();
    }
    
    public static void main(String args[]) throws Exception {
        //按指定宽高压缩图片
        String oldimg = "d:/123.jpg";   
        File file = new File(oldimg);
        System.out.println("旧图片大小："+file.length());
        String newimg = ImageCompressUtil.zipImageFile(oldimg, 800, 600, 0.05f);
        File f = new File(newimg);
        System.out.println("新图片大小："+f.length());
        //等比例压缩图片
        ImageCompressUtil.saveMinPhoto("d:/123.jpg", "d:/11.jpg", 139, 0.9d);
    }

}