import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
 
import javax.imageio.*;
public class FormatConversion {
  public static final String JPG = "jpg";
  public static final String GIF = "gif";
  public static final String PNG = "png";
  public static final String BMP = "bmp";
  public static void main(String[] args) {
    String src = "E:\\2.";
    new FormatConversion().Conversion(JPG,PNG,src);//JPG转成PNG
    new FormatConversion().Conversion(JPG,GIF,src);//JPG转成GIF
    new FormatConversion().Conversion(JPG,BMP,src);//JPG转成BMP
    //其余格式转化只要调用Conversion函数即可
  }
   
  //inputFormat表示原格式，outputFormat表示转化后的格式
  public void Conversion(String inputFormat,String outputFormat,String src){
     
    try {
      File input = new File(src+inputFormat);
      BufferedImage bim = ImageIO.read(input);
      File output = new File(src+outputFormat);
      ImageIO.write(bim, outputFormat, output);
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
 
}

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

public class ConverterUtil {

  // JGP格式
  public static final String JPG = "jpeg";
  // GIF格式
  public static final String GIF = "gif";
  // PNG格式
  public static final String PNG = "png";
  // BMP格式
  public static final String BMP = "bmp";
 
  
  public static void converter(File imgFile,String format,File formatFile)
      throws IOException{
    BufferedImage bIMG =ImageIO.read(imgFile);
    ImageIO.write(bIMG, format, formatFile);
  }
 
 
  
  public static void main(String[] args) {
    try {
      // 转换为JGP
      ConverterUtil.converter(new File("c:\\psb.jpg"),JPG, new File("c:\\psb2.jpg"));
      // 转换为GIF
      ConverterUtil.converter(new File("c:\\psb.jpg"),GIF, new File("c:\\psb2.gif"));
      // 转换为PNG
      ConverterUtil.converter(new File("c:\\psb.jpg"),PNG, new File("c:\\psb2.png"));
      // 转换为BMP
      ConverterUtil.converter(new File("c:\\psb.jpg"),BMP, new File("c:\\psb2.bmp"));
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

package cn.xsbiz.servlet.test; 
 
import java.io.FileOutputStream; 
import java.io.OutputStream; 
 
import javax.media.jai.JAI; 
import javax.media.jai.RenderedOp; 
 
import com.sun.media.jai.codec.BMPEncodeParam; 
import com.sun.media.jai.codec.ImageCodec; 
import com.sun.media.jai.codec.ImageEncoder; 
import com.sun.media.jai.codec.JPEGEncodeParam; 
 
/* 
 * 可以实现jpg/tif/bmp 等图片之间格式得互相转换 
 */ 
public class Test { 
 
  public static void main(String[] args) throws Exception { 
 
    /* tif转换到jpg格式 */ 
    String input2 = "d:/img/a.tif"; 
    String output2 = "d:/img/a.jpg"; 
    RenderedOp src2 = JAI.create("fileload", input2); 
    OutputStream os2 = new FileOutputStream(output2); 
    JPEGEncodeParam param2 = new JPEGEncodeParam(); 
    //指定格式类型，jpg 属于 JPEG 类型 
    ImageEncoder enc2 = ImageCodec.createImageEncoder("JPEG", os2, param2); 
    enc2.encode(src2); 
    os2.close(); 
     
     
    /*tif转换到bmp格式*/ 
    String inputFile = "d:/img/b.tif"; 
    String outputFile = "d:/img/b.bmp"; 
    RenderedOp src = JAI.create("fileload", inputFile); 
    OutputStream os = new FileOutputStream(outputFile); 
    BMPEncodeParam param = new BMPEncodeParam(); 
    ImageEncoder enc = ImageCodec.createImageEncoder("BMP", os,param); 
    enc.encode(src); 
    os.close();//关闭流 
     
    //其他的一样的方式转换 
 
  } 
 
}