JSP验证码

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原创最新推荐文章于 2026-03-28 02:37:55 发布 744 阅读 AI 写同款· GEO 优化 ›

JSP+Servlet实现图片验证码 我们在登录或者注册的过程中，常常会发现有验证码的存在，今天我们自己动手来实现一个图片验证码。首先，我们的验证码图片是在JSP页面中展示的，所以先从JSP页面着手。直接上代码。 login.jsp 欢迎登陆 /servlet/LoginServlet" method="get"> /servlet/Functio nServlet" id="i 阅读详情

<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" pageEncoding="UTF-8" %>
<%!
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 = 80, height = 30;
 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
 //List<String> list = new ArrayList<String>();
 //10种英文字体
 String[] strfont = {"Helvetica","Garamond","Frutiger","Bodoni","Futura","Times","Officina","Univers","Akzidenz", "Grotesk"};
 g.setFont(new Font(strfont[random.nextInt(10)], Font.BOLD, 16 + random.nextInt(4)));

 //画边框
 g.setColor(new Color(0, 0, 0));
 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 = null;
  //随机生成数字或者字母
  if (random.nextInt(10) > 5) {
   rand = String.valueOf((char)(random
     .nextInt(10) + 48));
  } else {
   rand = String.valueOf((char)(random
     .nextInt(26) + 65));
  }
  sRand += rand;
  // 将认证码显示到图象中
  g.setColor(new Color(random.nextInt(80), random.nextInt(80), random.nextInt(80)));
  //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, 15 * i + 7 + random.nextInt(8), 30 - random.nextInt(15));
 }

 // 将认证码存入SESSION
 session.setAttribute("randcode", sRand);

 // 图象生效
 g.dispose();

 // 输出图象到页面
 ImageIO.write(image, "JPEG", response.getOutputStream());
 response.flushBuffer();//防止异常getOutputStream() has already been called for this response
 out.clear();
 out = pageContext.pushBody();

%>

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