java 实现输出随机图片实例代码

java  实现输出随机图片实例代码

输出随机图片(captcha图像):completely automated public turing test to tell computers and humans apart (全自动区分计算机和人类的测试)

相关主要类(jdk 查看api)

bufferedimage:内存图像
graphics：画笔
imageio：输出图像

放在html页面上<img src/>

注意：浏览器默认会缓存图片

   public static int width = 120; 
public static int height = 25; 
 
public void doget(httpservletrequest request, httpservletresponse response) 
    throws servletexception, ioexception { 
 
  response.setcontenttype("text/html"); 
  //创建内存图像 
  bufferedimage image = new bufferedimage(width,height,bufferedimage.type_int_rgb); 
  //勾勒图像 
  graphics graphics = image.getgraphics(); 
  //设置背景 
  graphics.setcolor(color.white); 
  graphics.fillrect(0, 0, width, height); 
  //设置边框 
  graphics.setcolor(color.blue); 
  graphics.drawrect(1, 1, width-2, height-2); 
  //画干扰线 
  graphics.setcolor(color.yellow); 
  for(int i=0;i<8;i++){ 
    int xstart = new random().nextint(width); 
    int ystart = new random().nextint(height); 
    int xend = new random().nextint(width); 
    int yend = new random().nextint(height); 
    graphics.drawline(xstart, ystart, xend, yend); 
  } 
  //写随机数 
  graphics.setcolor(color.red); 
  int x = 5; 
  for(int i=0;i<4;i++){ 
    graphics.drawstring(new random().nextint(9)+"", x, 20); 
    x+=30; 
  } 
  response.setcontenttype("image/jpeg");//设置响应格式 
  imageio.write(image, "jpeg", response.getoutputstream()); 
   
} 

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