java图片压缩

	  /*** 
	   * 按指定的比例缩放图片 
	   * 
	   * @param sourceImagePath 
	   *      源地址 
	   * @param destinationPath 
	   *      改变大小后图片的地址 
	   * @param scale 
	   *      缩放比例，如1.2 
	   */
	  public static void scaleImage(String sourceImagePath, 
	      String destinationPath, double scale,String format) { 
	  
	    File file = new File(sourceImagePath); 
	    BufferedImage bufferedImage; 
	    try { 
	      bufferedImage = ImageIO.read(file); 
	      int width = bufferedImage.getWidth(); 
	      int height = bufferedImage.getHeight(); 
	  
	      width = parseDoubleToInt(width * scale); 
	      height = parseDoubleToInt(height * scale); 
	  
	      Image image = bufferedImage.getScaledInstance(width, height, 
	          Image.SCALE_SMOOTH); 
	      BufferedImage outputImage = new BufferedImage(width, height, 
	          BufferedImage.TYPE_INT_RGB); 
	      Graphics graphics = outputImage.getGraphics(); 
	      graphics.drawImage(image, 0, 0, null); 
	      graphics.dispose(); 
	  
	      ImageIO.write(outputImage, format, new File(destinationPath)); 
	    } catch (IOException e) { 
	      System.out.println("scaleImage方法压缩图片时出错了"); 
	      e.printStackTrace(); 
	    } 
	  
	  } 
	  
	  /*** 
	   * 将图片缩放到指定的高度或者宽度 
	   * @param sourceImagePath 图片源地址 
	   * @param destinationPath 压缩完图片的地址 
	   * @param width 缩放后的宽度 
	   * @param height 缩放后的高度 
	   * @param auto 是否自动保持图片的原高宽比例 
	   * @param format 图图片格式 例如 jpg 
	   * image.SCALE_SMOOTH //平滑优先
		 image.SCALE_FAST//速度优先
		 image.SCALE_AREA_AVERAGING //区域均值
		 image.SCALE_REPLICATE //像素复制型缩放
		 image.SCALE_DEFAULT //默认缩放模式
	   */
	  public static boolean scaleImageWithParams(String sourceImagePath, 
	      String destinationPath, int width, int height, boolean auto,String format) { 
		  File file =null;
	    try { 
	     file = new File(sourceImagePath); 
	    BufferedImage bufferedImage = null; 
	    bufferedImage = ImageIO.read(file); 
	      if (auto) { 
	        ArrayList<Integer> paramsArrayList = getAutoWidthAndHeight(bufferedImage,width,height); 
	        width = paramsArrayList.get(0); 
	        height = paramsArrayList.get(1); 
	        System.out.println("自动调整比例，width="+width+" height="+height); 
	      } 
	      
	    Image image = bufferedImage.getScaledInstance(width, height, 
	        Image.SCALE_REPLICATE); 
	    BufferedImage outputImage = new BufferedImage(width, height, 
	        BufferedImage.SCALE_REPLICATE); 
	    Graphics graphics = outputImage.getGraphics(); 
	    graphics.drawImage(image, 0, 0, null); 
	    graphics.dispose(); 
	    ImageIO.write(outputImage, format, new File(destinationPath)); 
	    } catch (Exception e) { 
	      System.out.println("scaleImageWithParams方法压缩图片时出错了"); 
	      e.printStackTrace(); 
	      return false; 
	    }finally {
	    	if (file!=null&&file.exists()) {
	    		 file.delete();
			}
	    }
		return true; 
	      
	      
	  } 
	  
	  /** 
	   * 将double类型的数据转换为int，四舍五入原则 
	   * 
	   * @param sourceDouble 
	   * @return 
	   */
	  private static int parseDoubleToInt(double sourceDouble) { 
	    int result = 0; 
	    result = (int) sourceDouble; 
	    return result; 
	  } 
	    
	  /*** 
	   * 
	   * @param bufferedImage 要缩放的图片对象 
	   * @param width_scale 要缩放到的宽度 
	   * @param height_scale 要缩放到的高度 
	   * @return 一个集合，第一个元素为宽度，第二个元素为高度 
	   */
	  private static ArrayList<Integer> getAutoWidthAndHeight(BufferedImage bufferedImage,int width_scale,int height_scale){ 
	    ArrayList<Integer> arrayList = new ArrayList<Integer>(); 
	    int width = bufferedImage.getWidth(); 
	    int height = bufferedImage.getHeight(); 
	    double scale_w =getDot2Decimal( width_scale,width); 
	      
	    System.out.println("getAutoWidthAndHeight width="+width + "scale_w="+scale_w); 
	    double scale_h = getDot2Decimal(height_scale,height); 
	    if (scale_w<scale_h) { 
	      arrayList.add(parseDoubleToInt(scale_w*width)); 
	      arrayList.add(parseDoubleToInt(scale_w*height)); 
	    } 
	    else { 
	      arrayList.add(parseDoubleToInt(scale_h*width)); 
	      arrayList.add(parseDoubleToInt(scale_h*height)); 
	    } 
	    return arrayList; 
	      
	  } 
	    
	    
	  /*** 
	   * 返回两个数a/b的小数点后三位的表示 
	   * @param a 
	   * @param b 
	   * @return 
	   */
	  public static double getDot2Decimal(int a,int b){ 
	      
	    BigDecimal bigDecimal_1 = new BigDecimal(a); 
	    BigDecimal bigDecimal_2 = new BigDecimal(b); 
	    BigDecimal bigDecimal_result = bigDecimal_1.divide(bigDecimal_2,new MathContext(4)); 
	    Double double1 = new Double(bigDecimal_result.toString()); 
	    System.out.println("相除后的double为："+double1); 
	    return double1; 
	  }