//设置响应头

         response.setCharacterEncoding("image/jpeg");

         int width=160;

         int height=40;

         BufferedImage image=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

         Graphics g=image.getGraphics();

         Graphics2D g2d = (Graphics2D) g;

         g2d.setColor(Color.WHITE);

         g2d.fillRect(0, 0, width, height);

         g2d.setFont(new Font("宋体", Font.BOLD, 18));

          Random random=new Random();

         for(int i=0;i<4;i++)//获取随机四个汉字

         {

             Color c=new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256));

             String s=GetStr();

             AffineTransform aff = new AffineTransform();

             aff.rotate(Math.random(),i*10,height-20);//旋转

             aff.scale(0.2+Math.random(), 0.2+Math.random());//缩放

             g2d.setTransform(aff);

             System.err.println(">:"+s);        

             g2d.setColor(c);

             g2d.drawString(s, i*10, height- 5);

         }

         for(int i=0;i<3;i++)    //干扰线

         {

             Color c=new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256));

             g2d.setColor(c);

             g2d.drawLine(random.nextInt(width), random.nextInt(height), random.nextInt(width), random.nextInt(height));

         }

         g2d.dispose();//图片生效

         ImageIO.write(image, "jpeg", response.getOutputStream());//输出

         System.out.println("输出");

     }

     //获取汉字

     private static String GetStr()

     {

         String str = null;

         try {

             int hightPos, lowPos; // 定义高低位

             Random random = new Random();

             hightPos = (176 + Math.abs(random.nextInt(39)));//获取高位值

             lowPos = (161 + Math.abs(random.nextInt(93)));//获取低位值

             byte[] b = new byte[2];

             b[0] = (new Integer(hightPos).byteValue());

             b[1] = (new Integer(lowPos).byteValue());

             str = new String(b, "GBK");//转成中文

         } catch (Exception e) {

             e.printStackTrace();

         }

         return str;

     }