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
      *  width: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