ImageIO.writer를 사용하여 BufferedImage에서 JPEG 이미지를 생성하는 Java에 대한 자세한 설명, 발생한 문제에 대한 요약 및 솔루션

  /**
   * 将原图压缩生成jpeg格式的数据
   * @param source
   * @return
   */
  public static byte[] wirteJPEGBytes(BufferedImage source){
    if(null==source)
      throw new NullPointerException();
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    JPEGImageEncoder jencoder = JPEGCodec.createJPEGEncoder(output);
    JPEGEncodeParam param = jencoder.getDefaultJPEGEncodeParam(source);
    param.setQuality(0.75f, true);
    jencoder.setJPEGEncodeParam(param);
    try {
      jencoder.encode(source);
    } catch (ImageFormatException e) {
      throw new RuntimeException(e);
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
    return output.toByteArray();  
  }

  /**
   * 将原图压缩生成jpeg格式的数据
   * @param source
   * @return
   * @see #wirteBytes(BufferedImage, String)
   */
  public static byte[] wirteJPEGBytes(BufferedImage source){
    return wirteBytes(source,"JPEG");
  }
  /**
   * 将原图压缩生成jpeg格式的数据
   * @param source
   * @return
   * @see #wirteBytes(BufferedImage, String)
   */
  public static byte[] wirteJPEGBytes(BufferedImage source){
    return wirteBytes(source,"JPEG");
  }
  /**
   * 将{@link BufferedImage}生成formatName指定格式的图像数据
   * @param source
   * @param formatName 图像格式名，图像格式名错误则抛出异常
   * @return
   */
  public static byte[] wirteBytes(BufferedImage source,String formatName){
    Assert.notNull(source, "source");
    Assert.notEmpty(formatName, "formatName");
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    try {      
      if(!ImageIO.write(source, formatName.toLowerCase(), output))
        // 返回false则抛出异常
        throw new IllegalArgumentException(String.format("not found writer for '%s'",formatName));

    } catch (IOException e) {
      throw new RuntimeException(e);
    }
    return output.toByteArray();    
  }