在servlet里怎么对一张图片做缩略图？

Question

import java.io.*;
import java.util.*;
import com.sun.image.codec.jpeg.*;
import java.awt.image.*;
import java.awt.*;
import java.net.*;
import java.applet.*;
import java.sql.*;
import FileDeal.*;  public String  SWitchFile_particular(String InputDir,String OutputDir,String InputFileName,String OutputFileName)
  //指定输入文件名和输出文件名以及输入和输出路径的，单个文件的缩略图的生成的函数
  {
                         BufferedImage image;
                         String NewFileName;//--------------------------------------------------------------------------------
//设定输出文件句柄
                            File file = new File(OutputDir+OutputFileName);
                            FileOutputStream tempout =null;
                            try{
                              tempout= new FileOutputStream(file);
                            }
                            catch(Exception ex)
                            {
                              System.out.println(ex.toString());
                            }
//--------------------------------------------------------------------------------                            Image img=null;
                            Toolkit tk=Toolkit.getDefaultToolkit();
                            Applet app=new Applet();
                            MediaTracker mt = new MediaTracker(app);
                            try {
//得到输入文件
                              img=tk.getImage(InputDir+InputFileName);
                              mt.addImage(img, 0);
                              mt.waitForID(0);
                 }
                 catch(Exception e) {
        e.printStackTrace();
            }
                            if(img.getWidth(null)==-1)
                            {
                              System.out.println("   can't read,retry!"+"<BR>");
                            }
                            else
                            {
                              double rate1=((double)img.getWidth(null))/80.0+0.1;
                              double rate2=((double)img.getHeight(null))/80.0+0.1;
                              double rate=rate1>rate2?rate1:rate2;                              int new_w=(int)(((double)img.getWidth(null))/rate);
                              int new_h=(int)(((double)img.getHeight(null))/rate);
//                              BufferedImage buffImg = new BufferedImage(new_w,new_h,BufferedImage.TYPE_INT_RGB);
                              BufferedImage buffImg = new BufferedImage(new_w,new_h,BufferedImage.TYPE_INT_RGB);                              Graphics g = buffImg.createGraphics();                              g.setColor(Color.white);
                              g.fillRect(0,0,new_w,new_h);                              g.drawImage(img,0,0,new_w,new_h,null);
                              g.dispose();                              JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(tempout);
                              try
                              {
                                encoder.encode(buffImg);
                                tempout.close();
                              }
                              catch(IOException ex)
                              {
                                System.out.println(ex.toString());
                              }
                             }
    return "ok";
  }
要将50分都给我哦！