java 将图片按照指定的图片尺寸压缩

import java.awt.Graphics2D; 
import java.awt.Image; 
import java.awt.image.BufferedImage; 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.IOException; 
import javax.imageio.ImageIO; 
 
/**
* * @author WQ * @date 2011-01-14 * @versions 1.0 图片压缩工具类 提供的方法中可以设定生成的
* 缩略图片的大小尺寸等
*/ 
public class ImageUtil { 
    /** * 图片文件读取 * * @param srcImgPath * @return */ 
    private static BufferedImage InputImage(String srcImgPath) { 
        BufferedImage srcImage = null; 
        try { 
            FileInputStream in = new FileInputStream(srcImgPath); 
            srcImage = javax.imageio.ImageIO.read(in); 
        } catch (IOException e) { 
            System.out.println("读取图片文件出错！" + e.getMessage()); 
            e.printStackTrace(); 
        } 
        return srcImage; 
    } 
  public static void main(String args[]){
try {
Map<Integer, String> map = readfile("E:/yuan", null);
for (int i = 0; i < map.size(); i++) {
System.out.println(map.get(i) + " ==" + i);
System.out.println();
String oldpath = map.get(i);
compressImage(map.get(i), "E:/ww/_" + i + ".png", 100, 75);
}
} catch (Exception ex) {
}
System.out.println("ok");
  }
    /**
     * * 将图片按照指定的图片尺寸压缩 * * @param srcImgPath :源图片路径 * @param outImgPath *
     * :输出的压缩图片的路径 * @param new_w * :压缩后的图片宽 * @param new_h * :压缩后的图片高
     */ 
    public static void compressImage(String srcImgPath, String outImgPath, 
            int new_w, int new_h) { 
        BufferedImage src = InputImage(srcImgPath); 
        disposeImage(src, outImgPath, new_w, new_h); 
    } 
 
    /**
     * * 指定长或者宽的最大值来压缩图片 * * @param srcImgPath * :源图片路径 * @param outImgPath *
     * :输出的压缩图片的路径 * @param maxLength * :长或者宽的最大值
     */ 
    public static void compressImage(String srcImgPath, String outImgPath, 
            int maxLength) { 
        // 得到图片 
        BufferedImage src = InputImage(srcImgPath); 
        if (null != src) { 
            int old_w = src.getWidth(); 
            // 得到源图宽 
            int old_h = src.getHeight(); 
            // 得到源图长 
            int new_w = 0; 
            // 新图的宽 
            int new_h = 0; 
            // 新图的长 
            // 根据图片尺寸压缩比得到新图的尺寸 
            if (old_w > old_h) { 
                // 图片要缩放的比例 
                new_w = maxLength; 
                new_h = (int) Math.round(old_h * ((float) maxLength / old_w)); 
            } else { 
                new_w = (int) Math.round(old_w * ((float) maxLength / old_h)); 
                new_h = maxLength; 
            } 
            disposeImage(src, outImgPath, new_w, new_h); 
        } 
    } 
 
    /** * 处理图片 * * @param src * @param outImgPath * @param new_w * @param new_h */ 
    private synchronized static void disposeImage(BufferedImage src, 
            String outImgPath, int new_w, int new_h) { 
        // 得到图片 
        int old_w = src.getWidth(); 
        // 得到源图宽 
        int old_h = src.getHeight(); 
        // 得到源图长 
        BufferedImage newImg = null; 
        // 判断输入图片的类型 
        switch (src.getType()) { 
        case 13: 
            // png,gifnewImg = new BufferedImage(new_w, new_h, 
            // BufferedImage.TYPE_4BYTE_ABGR); 
            break; 
        default: 
            newImg = new BufferedImage(new_w, new_h, BufferedImage.TYPE_INT_RGB); 
            break; 
        } 
        Graphics2D g = newImg.createGraphics(); 
        // 从原图上取颜色绘制新图 
        g.drawImage(src, 0, 0, old_w, old_h, null); 
        g.dispose(); 
        // 根据图片尺寸压缩比得到新图的尺寸 
        newImg.getGraphics().drawImage( 
                src.getScaledInstance(new_w, new_h, Image.SCALE_SMOOTH), 0, 0, 
                null); 
        // 调用方法输出图片文件 
        OutImage(outImgPath, newImg); 
    } 
 
    /**
     * * 将图片文件输出到指定的路径，并可设定压缩质量 * * @param outImgPath * @param newImg * @param
     * per
     */ 
    private static void OutImage(String outImgPath, BufferedImage newImg) { 
        // 判断输出的文件夹路径是否存在，不存在则创建 
        File file = new File(outImgPath); 
        if (!file.getParentFile().exists()) { 
            file.getParentFile().mkdirs(); 
        }// 输出到文件流 
        try { 
            ImageIO.write(newImg, outImgPath.substring(outImgPath 
                    .lastIndexOf(".") + 1), new File(outImgPath)); 
        } catch (FileNotFoundException e) { 
            e.printStackTrace(); 
        } catch (IOException e) { 
            e.printStackTrace(); 
        } 
    } 
public static Map<Integer, String> readfile(String filepath,
Map<Integer, String> pathMap) throws Exception {
if (pathMap == null) {
pathMap = new HashMap<Integer, String>();
}

File file = new File(filepath);
// 文件
if (!file.isDirectory()) {
pathMap.put(pathMap.size(), file.getPath());

} else if (file.isDirectory()) { // 如果是目录， 遍历所有子目录取出所有文件名
String[] filelist = file.list();
for (int i = 0; i < filelist.length; i++) {
File readfile = new File(filepath + "/" + filelist[i]);
if (!readfile.isDirectory()) {
pathMap.put(pathMap.size(), readfile.getPath());

} else if (readfile.isDirectory()) { // 子目录的目录
readfile(filepath + "/" + filelist[i], pathMap);
}
}
}
return pathMap;
}
} 
转http://lijinzhe.blog.163.com/blog/static/62147668201222024822711/