java,图片压缩,略缩图

在网上找了两个图片的缩放类，在这里分享一下：

package manager.util;
import java.util.Calendar;
import java.io.File;
import java.awt.image.BufferedImage;
import java.awt.Image;
import java.awt.image.AffineTransformOp;
import javax.imageio.ImageIO;
import java.awt.geom.AffineTransform;
public class UploadImg {
    String fromFileStr;
    String saveToFileStr;
    String sysimgfile;
    int width;
    int height;
    String suffix;
    /**
     * @param fromFileStr
     *            原始图片完整路径
     * @param saveToFileStr
     *            缩略图片保存路径
     * @param sysimgfilenNow
     *            处理后的图片文件名前缀
     * 
     */
    public UploadImg(String fromFileStr, String saveToFileStr, String sysimgfile,String suffix,int width,int height) {
        this.fromFileStr = fromFileStr;
        this.saveToFileStr = saveToFileStr;
        this.sysimgfile = sysimgfile;
        this.width=width;
        this.height=height;
        this.suffix=suffix;
    }
    public boolean createThumbnail() throws Exception {
        // fileExtNmae是图片的格式 gif JPG 或png
        // String fileExtNmae="";
        double Ratio = 0.0;
        File F = new File(fromFileStr);
        if (!F.isFile())
            throw new Exception(F
                    + " is not image file error in CreateThumbnail!");
        File ThF = new File(saveToFileStr, sysimgfile +"."+suffix);
        BufferedImage Bi = ImageIO.read(F);
        Image Itemp = Bi.getScaledInstance(width, height, Bi.SCALE_SMOOTH);
        if ((Bi.getHeight() > width) || (Bi.getWidth() > height)) {
            if (Bi.getHeight() > Bi.getWidth())
                Ratio = (double)width / Bi.getHeight();
            else
                Ratio = (double)height / Bi.getWidth();
        }
        AffineTransformOp op = new AffineTransformOp(AffineTransform
                .getScaleInstance(Ratio, Ratio), null);
        Itemp = op.filter(Bi, null);
        try {
            ImageIO.write((BufferedImage) Itemp, suffix, ThF);
        } catch (Exception ex) {
            throw new Exception(" ImageIo.write error in CreatThum.: "
                    + ex.getMessage());
        }
        return (true);
    }
    public static void main(String[] args) {
        UploadImg UI;
        boolean ss = false;
        try {
            UI = new UploadImg("d://FairyTaleVector040.png", "d://temp", "ps_low1","png",650,650);
            ss = UI.createThumbnail();
            if (ss) {
                System.out.println("Success");
            } else {
                System.out.println("Error");
            }
        } catch (Exception e) {
            System.out.print(e.toString());
        }
    }
}

这个类，可以对jpg、png、gif三种图片缩放，缩放按等比例缩放

package manager.util;
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 Thumbnail {
    /**
     * 生成缩略图 
     * fromFileStr:原图片路径
     *  saveToFileStr:缩略图路径 
     *  缩略图的宽 
     *  height:缩略图的高
     */
    public static void saveImageAsJpg(String fromFileStr, String saveToFileStr,
            int width, int height,boolean equalProportion) throws Exception {
        BufferedImage srcImage;
        String imgType="JPEG";
        if(fromFileStr.toLowerCase().endsWith(".png")){
            imgType="PNG";
        }
        File fromFile=new File(fromFileStr);
        File saveFile=new File(saveToFileStr);
        srcImage=ImageIO.read(fromFile);
        if(width>0||height>0){
            srcImage=resize(srcImage,width,height,equalProportion);
        }
        ImageIO.write(srcImage,imgType,saveFile);
    }
    
    /**
     * 将原图片的BufferedImage对象生成缩略图
     * source：原图片的BufferedImage对象
     * targetW:缩略图的宽
     * targetH:缩略图的高
     */
    public static BufferedImage resize(BufferedImage source,int targetW,int targetH,boolean equalProportion){
        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范围内实现等比例的缩放
          //如果不需要等比例的缩放则下面的if else语句注释调即可
        if(equalProportion){
            if(sx>sy){
                sx=sy;
                targetW=(int)(sx*source.getWidth());
            }else{
                sy=sx;
                targetH=(int)(sx*source.getHeight());
            }
        }
        if(type==BufferedImage.TYPE_CUSTOM){
            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();
            g.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
            g.drawRenderedImage(source,AffineTransform.getScaleInstance(sx,sy));
            g.dispose();
        }
        return target;
    }
    
    public static void main(String[] args){
        try{
            Thumbnail.saveImageAsJpg("D://FairyTaleVector040.png", "D://temp//test.png", 480, 480,true);
        }catch(Exception e){
            e.printStackTrace();
        }
    }
}

这个类只能对jpg图片缩放，但是提供了两种缩放方式：等比例和不等比例

 以上内容来自: http://blog.csdn.net/tianhandigeng1498/article/details/6053835