java 生成略缩图

import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.WritableRaster;
import java.io.File;

import javax.imageio.ImageIO;


public class a {

public static BufferedImage resize(BufferedImage source, int targetW, int targetH) {
        // targetW，targetH分别表示目标长和宽
        int type = source.getType();
        BufferedImage target = null;
        double sx = (double) targetW / source.getWidth();
        double sy = (double) targetH / source.getHeight();
        //这里想实现在targetW，targetH范围内实现等比缩放。如果不需要等比缩放
        //则将下面的if else语句注释即可
        if(sx>sy)
        {
            sx = sy;
            targetW = (int)(sx * source.getWidth());
        }else{
            sy = sx;
            targetH = (int)(sy * source.getHeight());
        }
        if (type == BufferedImage.TYPE_CUSTOM) { //handmade
            ColorModel cm = source.getColorModel();
            WritableRaster raster = cm.createCompatibleWritableRaster(targetW, targetH);
            boolean alphaPremultiplied = cm.isAlphaPremultiplied();
            target = new BufferedImage(cm, raster, alphaPremultiplied, null);
        } else
            target = new BufferedImage(targetW, targetH, type);
            Graphics2D g = target.createGraphics();
            //smoother than exlax:
            g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY );
            g.drawRenderedImage(source, AffineTransform.getScaleInstance(sx, sy));
            g.dispose();
            return target;
        }
   
        public static void saveImageAsJpg (String fromFileStr,String saveToFileStr,int width,int hight)
        throws Exception {
        BufferedImage srcImage;
        // String ex = fromFileStr.substring(fromFileStr.indexOf("."),fromFileStr.length());
        String imgType = "JPEG";
        if (fromFileStr.toLowerCase().endsWith(".png")) {
            imgType = "PNG";
        }
        // System.out.println(ex);
        File saveFile=new File(saveToFileStr);
        File fromFile=new File(fromFileStr);
        srcImage = ImageIO.read(fromFile);
        if(width > 0 || hight > 0)
        {
            srcImage = resize(srcImage, width, hight);
        }
        ImageIO.write(srcImage, imgType, saveFile);

    }
   
    public static void main (String argv[]) {
        try{
        //参数1(from),参数2(to),参数3(宽),参数4(高)
            saveImageAsJpg("/home/liguojun/NetWork.jpg",
                    "/home/liguojun/NetWork1.jpg",
                    120,120);
        } catch(Exception e){
            e.printStackTrace();
        }

    }
}