java生成jpeg/png图片时，设置图片质量

import   java.awt.BasicStroke;  
  import   java.awt.Color;  
  import   java.awt.Graphics2D;  
  import   java.awt.RenderingHints;  
  import   java.awt.image.BufferedImage;  
  import   java.io.File;  
  import   java.io.IOException;  
  import   java.util.Iterator;  
  import   java.util.Random;  
    
  import   javax.imageio.*;  
  import   javax.imageio.stream.ImageOutputStream;  
    
  public   class   ImageIOTest   {  
          public   static   void   main(String[]   args)   throws   IOException   {  
                  int   width   =   800;  
                  int   height   =   800;  
    
                  BufferedImage   image   =   new   BufferedImage(  
                                  width,   height,   BufferedImage.TYPE_INT_RGB);  
                  Graphics2D   g2d   =   image.createGraphics();  
                  g2d.setColor(Color.white);  
                  g2d.fillRect(0,   0,   width,   height);  
                  g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,    
                                  RenderingHints.VALUE_ANTIALIAS_ON);  
                  Random   random   =   new   Random();  
                  for   (int   i   =   0;   i   <   500;   i++)   {  
                          g2d.setColor(new   Color(random.nextInt(256),    
                                          random.nextInt(256),   random.nextInt(256)));  
                          g2d.setStroke(new   BasicStroke(random.nextFloat()   *   5));  
                            
                          int   r   =   random.nextInt(width   /   2);  
                          g2d.drawArc(random.nextInt(width),   random.nextInt(height),    
                                          r,   r,   0,   360);  
                  }  
                  g2d.dispose();  
                    
    
                  ImageWriter   writer   =   null;  
                  ImageTypeSpecifier   type   =  
                          ImageTypeSpecifier.createFromRenderedImage(image);  
                  Iterator   iter   =   ImageIO.getImageWriters(type,   "jpg");  
                  if   (iter.hasNext())   {  
                          writer   =   (ImageWriter)iter.next();  
                  }  
                  if   (writer   ==   null)   {  
                          return;  
                  }  
                  IIOImage   iioImage   =   new   IIOImage(image,   null,   null);  
                  ImageWriteParam   param   =   writer.getDefaultWriteParam();  
    
                  param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);  
                  for   (int   i   =   0;   i   <   10;   i++)   {  
                          param.setCompressionQuality((float)   ((i+1)   /   10.0));  
                          ImageOutputStream   outputStream   =    
                                  ImageIO.createImageOutputStream(new   File("C:/test"   +   (i+1)   +   ".jpg"));  
                          writer.setOutput(outputStream);  
                          writer.write(null,   iioImage,   param);  
                  }  
          }  
  }