picture.jsp

图片验证码

<%@   page   contentType="image/jpeg"   import="java.awt.*,
  java.awt.image.*,java.util.*,javax.imageio.*"   %>
  <%!
  Color   getRandColor(int   fc,int   bc){//给定范围获得随机颜色
  Random   random   =   new   Random();
  if(fc>255)   fc=255;
  if(bc>255)   bc=255;
  int   r=fc+random.nextInt(bc-fc);
  int   g=fc+random.nextInt(bc-fc);
  int   b=fc+random.nextInt(bc-fc);
  return   new   Color(r,g,b);
  }
  %>
  <%
  //设置页面不缓存
  response.setHeader("Pragma","No-cache");
  response.setHeader("Cache-Control","no-cache");
  response.setDateHeader("Expires",   0);

  //   在内存中创建图象
  int   width=60,   height=20;
  BufferedImage   image   =   new   BufferedImage(width,   height,   BufferedImage.TYPE_INT_RGB);

  //   获取图形上下文
  Graphics   g   =   image.getGraphics();

  //生成随机类
  Random   random   =   new   Random();

  //   设定背景色
  g.setColor(getRandColor(200,250));
  g.fillRect(0,   0,   width,   height);

  //设定字体
  g.setFont(new   Font("Times   New   Roman",Font.PLAIN,18));

  //画边框
  //g.setColor(new   Color());
  //g.drawRect(0,0,width-1,height-1);

  //   随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
  g.setColor(getRandColor(160,200));
  for   (int   i=0;i<155;i++)
  {
  int   x   =   random.nextInt(width);
  int   y   =   random.nextInt(height);
  int   xl   =   random.nextInt(12);
  int   yl   =   random.nextInt(12);
  g.drawLine(x,y,x+xl,y+yl);
  }

  //   取随机产生的认证码(4位数字)
  String   sRand="";
  for   (int   i=0;i<4;i++){
  String   rand=String.valueOf(random.nextInt(10));
  sRand+=rand;
  //   将认证码显示到图象中
  g.setColor(new   Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
  //调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
  g.drawString(rand,13*i+6,16);
  }

  //   将认证码存入SESSION
  session.setAttribute("rand",sRand);
  System.out.println(sRand);
  //   图象生效
  g.dispose();

  //   输出图象到页面
  ImageIO.write(image,   "JPEG",   response.getOutputStream());
  %>