java实现图像缩略

//缩略图实现，将图片(jpg,gif,bmp等等)真实的变成想要的大小
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.*;
//缩略图类，
//本java类能将jpg图片文件，进行等比或非等比的大小转换。
//具体使用方法
//s_pic(大图片路径,生成小图片路径,大图片文件名,生成小图片文名,生成小图片宽度,生成小图片高度,是否等比缩放(默认为true))
public class DwindlePic{
  String InputDir; //输入图路径
  String OutputDir; //输出图路径
  String InputFileName; //输入图文件名
  String OutputFileName; //输出图文件名
  int OutputWidth = 80; //默认输出图片宽
  int OutputHeight = 80; //默认输出图片高
  int rate = 0;
  boolean proportion = true; //是否等比缩放标记(默认为等比缩放)
 
  public DwindlePic() {
    //初始化变量
    InputDir = "";
    OutputDir = "";
    InputFileName = "";
    OutputFileName = "";
    OutputWidth = 80;
    OutputHeight = 80;
    rate = 0;
  }
 
  public void setInputDir(String InputDir) {
    this.InputDir = InputDir;
  }
 
  public void setOutputDir(String OutputDir) {
    this.OutputDir = OutputDir;
  }
 
  public void setInputFileName(String InputFileName) {
    this.InputFileName = InputFileName;
  }
 
  public void setOutputFileName(String OutputFileName) {
    this.OutputFileName = OutputFileName;
  }
 
  public void setOutputWidth(int OutputWidth) {
    this.OutputWidth = OutputWidth;
  }
 
  public void setOutputHeight(int OutputHeight) {
    this.OutputHeight = OutputHeight;
  }
 
  public void setW_H(int width, int height) {
    this.OutputWidth = width;
    this.OutputHeight = height;
  }
 
  public String s_pic() {
    BufferedImage image;
    String NewFileName;
//建立输出文件对象
    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 {
      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>");
      return "no";
    }
    else {
      int new_w;
      int new_h;
      if (this.proportion == true) { //判断是否是等比缩放.
//为等比缩放计算输出的图片宽度及高度
        double rate1 = ( (double) img.getWidth(null)) / (double) OutputWidth +
            0.1;
        double rate2 = ( (double) img.getHeight(null)) / (double) OutputHeight +
            0.1;
        double rate = rate1 > rate2 ? rate1 : rate2;
        new_w = (int) ( ( (double) img.getWidth(null)) / rate);
        new_h = (int) ( ( (double) img.getHeight(null)) / rate);
      }
      else {
        new_w = OutputWidth; //输出的图片宽度
        new_h = OutputHeight; //输出的图片高度
      }
      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";
  }
 
  public String s_pic(String InputDir, String OutputDir, String InputFileName,
                      String OutputFileName) {
//输入图路径
    this.InputDir = InputDir;
//输出图路径
    this.OutputDir = OutputDir;
//输入图文件名
    this.InputFileName = InputFileName;
//输出图文件名
    this.OutputFileName = OutputFileName;
    return s_pic();
  }
 
  public String s_pic(String InputDir, String OutputDir, String InputFileName,
                      String OutputFileName, int
                      width, int height, boolean gp) {
//输入图路径
    this.InputDir = InputDir;
//输出图路径
    this.OutputDir = OutputDir;
//输入图文件名
    this.InputFileName = InputFileName;
//输出图文件名
    this.OutputFileName = OutputFileName;
//设置图片长宽
    setW_H(width, height);
//是否是等比缩放 标记
    this.proportion = gp;
    return s_pic();
  }
/**
  public static void main(String[] a)
  {
//s_pic(大图片路径,生成小图片路径,大图片文件名,生成小图片文名,生成小图片宽度,生成小图片高度)
    DwindlePic mypic = new DwindlePic();
    System.out.println(
        mypic.s_pic("e:\\Tomcat\\webapps\\pms\\image\\",
                    "e:\\Tomcat\\webapps\\pms\\image\\",
                    "test.jpg", "new.jpg", 120, 80, true)
        );
  }
*/
}