Java的图片缩放

package test;

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 fromdir; // fromdir 图片的原始目录

     String todir; // todir 处理后的图片存放目录

     String imgfile; // imgfile 原始图片

     String sysimgfile; // sysimgfile 处理后的图片文件名前缀

     UploadImg(String fromdirNow, String todirNow, String imgfileNow,
             String sysimgfileNow) ...{
         fromdir = fromdirNow;
         todir = todirNow;
         imgfile = imgfileNow;
         sysimgfile = sysimgfileNow;
     }

    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(fromdir, imgfile);
        if (!F.isFile())
            throw new Exception(F
                    + " is not image file error in CreateThumbnail!");
         File ThF = new File(todir, sysimgfile + ".jpg");

         BufferedImage Bi = ImageIO.read(F);
        // 假设图片宽 高 最大为300 3000
         Image Itemp = Bi.getScaledInstance(300, 300, Bi.SCALE_SMOOTH);

        if ((Bi.getHeight() > 300) || (Bi.getWidth() > 300)) ...{
            if (Bi.getHeight() > Bi.getWidth())
                 Ratio = 300.0 / Bi.getHeight();
            else
                 Ratio = 300.0 / Bi.getWidth();
         }

         AffineTransformOp op = new AffineTransformOp(AffineTransform
                 .getScaleInstance(Ratio, Ratio), null);
         Itemp = op.filter(Bi, null);
        try ...{
             ImageIO.write((BufferedImage) Itemp, "jpg", 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:/test", "d:/test", "ae86.jpg", "ps_low1");
             ss = UI.CreateThumbnail();
            if (ss) ...{
                 System.out.println("Success");
             } else ...{
                 System.out.println("Error");
             }
         } catch (Exception e) ...{
             System.out.print(e.toString());
         }
     }
}