java servlet实现图形验证码

1.开发环境

         |--tomcat 7

      |--eclipse

      |--jdk 1.7

2.项目结构     

       |-- demo

           |-- src

               |-- asia.hchx.filter

                   |-- CharacterFilter

                   |-- LoginFilter

              |-- asia.hchx.servlet

                   |-- LoginServlet

                   |-- VerifyImage

           |-- WebContent

               |-- index.jsp

               |-- login.jsp

3.测试步骤

   |--创建web项目

       |-- 配置开发图形验证码Servlet

    package asia.phome.servlet;            import java.awt.Color;      import java.awt.Font;      import java.awt.Graphics;      import java.awt.image.BufferedImage;      import java.io.IOException;      import java.io.OutputStream;      import java.util.Random;            import javax.imageio.ImageIO;      import javax.servlet.ServletException;      import javax.servlet.annotation.WebServlet;      import javax.servlet.http.HttpServlet;      import javax.servlet.http.HttpServletRequest;      import javax.servlet.http.HttpServletResponse;            @WebServlet("/verifyCode.do")      public class VerifyImage extends HttpServlet {                // 产生随即的字体          private Font getFont() {              Random random = new Random();              Font font[] = new Font[5];              font[0] = new Font("Ravie", Font.PLAIN, 24);              font[1] = new Font("Antique Olive Compact", Font.PLAIN, 24);              font[2] = new Font("Forte", Font.PLAIN, 24);              font[3] = new Font("Wide Latin", Font.PLAIN, 24);              font[4] = new Font("Gill Sans Ultra Bold", Font.PLAIN, 24);              return font[random.nextInt(5)];          }                protected void doGet(HttpServletRequest req, HttpServletResponse resp)                  throws ServletException, IOException {              // 设置响应头 Content-type类型              resp.setContentType("image/jpeg");              // 以下三句是用于设置页面不缓存              resp.setHeader("Pragma", "No-cache");              resp.setHeader("Cache-Control", "No-cache");              resp.setDateHeader("Expires", 0);                    OutputStream os = resp.getOutputStream();              int width = 83, height = 30;                            // 建立指定宽、高和BufferedImage对象              BufferedImage image = new BufferedImage(width, height,                      BufferedImage.TYPE_INT_RGB);                    Graphics g = image.getGraphics(); // 该画笔画在image上              Color c = g.getColor(); // 保存当前画笔的颜色，用完画笔后要回复现场              g.fillRect(0, 0, width, height);                    char[] ch = "abcdefghigklmnopqrstuvwxyz"                      .concat("ABCDEFGHIJKLMNOPQRSTUV")                      .concat("WXYZ0123456789").toCharArray(); // 随即产生的字符串                                                                              // 不包括 i                                                                              // l(小写L)                                                                              // o（小写O）                                                                              // 1（数字1）0(数字0)              int length = ch.length; // 随即字符串的长度              String sRand = ""; // 保存随即产生的字符串              Random random = new Random();              for (int i = 0; i < 4; i++) {                  // 设置字体                  g.setFont(getFont());                  // 随即生成0-9的数字                  String rand = new Character(ch[random.nextInt(length)]).toString();                  sRand += rand;                  // 设置随机颜色                  g.setColor(new Color(random.nextInt(255), random.nextInt(255),                          random.nextInt(255)));                  g.drawString(rand, 20 * i + 6, 25);              }              // 产生随即干扰点              for (int i = 0; i < 40; i++) {                  int x1 = random.nextInt(width);                  int y1 = random.nextInt(height);                  g.drawOval(x1, y1, 2, 2);              }              g.setColor(c); // 将画笔的颜色再设置回去              g.dispose();                    // 将验证码记录到session              req.getSession().setAttribute("safecode", sRand);              // 输出图像到页面              ImageIO.write(image, "JPEG", os);          }                protected void doPost(HttpServletRequest req, HttpServletResponse resp)                  throws ServletException, IOException {              doGet(req, resp);          }            }  

    |-- 登录页面配置图形验证码login.jsp

    <%@ page language="java" contentType="text/html; charset=UTF-8"          pageEncoding="UTF-8"%>      <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">      <html>      <head>      <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">      <title>Insert title here</title>      </head>      <body>          <form method="post" action="${pageContext.request.contextPath }/login.do">              username:<input type="text" name="username"/><br />              password:<input type="text" name="password"/><br />              <!-- img中的src属性中，配置VerifyImage的请求 -->              verify code:<img src="${pageContext.request.contextPath }/verifyCode.do"/>              <input type="text" name="verifyCode"/>              <br />              <input type="checkbox" value="1" name="rememberMe"/>记住密码              <br />              <input type="submit" value="登陆"/>          </form>      </body>      </html>  

    |-- 登录的Servlet配置——LoginServlet

    package asia.phome.servlet;            import java.io.IOException;            import javax.servlet.ServletException;      import javax.servlet.annotation.WebServlet;      import javax.servlet.http.Cookie;      import javax.servlet.http.HttpServlet;      import javax.servlet.http.HttpServletRequest;      import javax.servlet.http.HttpServletResponse;            import org.apache.log4j.Logger;            @WebServlet("/login.do")      public class LoginServlet extends HttpServlet{                    Logger log = Logger.getLogger(LoginServlet.class);                @Override          protected void doGet(HttpServletRequest req, HttpServletResponse resp)                  throws ServletException, IOException {              log.debug("开始执行doGet方法");              this.doPost(req, resp);          }                @Override          protected void doPost(HttpServletRequest req, HttpServletResponse resp)                  throws ServletException, IOException {              log.debug("开始执行doPost方法");                            req.setCharacterEncoding("UTF-8");              resp.setContentType("text/html;charset=UTF-8");                            log.debug("开始接收参数");              String username = req.getParameter("username");              String password = req.getParameter("password");              String safeCode = req.getParameter("verifyCode");                            log.debug("接收到参数:username ="                       + username                       + ";password=" + password                      + ";safecode=" + safeCode);                            // 获取验证码              String sc = (String) req.getSession().getAttribute("safecode");              log.warn("服务器中的验证码：" + sc);              if (!sc.equalsIgnoreCase(safeCode)) {                  log.warn("验证码输入有误!");                  resp.sendRedirect("login.jsp");                  return;              }                            String isRe = req.getParameter("rememberMe");              log.debug("是否记住密码：" + isRe);              if ("1".equals(isRe)) {                  /*                  *  记住密码                  *  在客户端的Cookie中，写入一个字符串标识                  */                  // 创建cookie                  log.debug("创建Cookie");                  Cookie cookie = new Cookie("rememberMe", username);                  // 将cookie绑定到响应中                  log.debug("绑定Cookie到响应中");                  resp.addCookie(cookie);              }                            if ("admin".equals(username)                      && "admin".equals(password)) {                    log.debug("登录成功，跳转到Index.jsp页面");                  req.getSession().setAttribute("loginuser", username);                  resp.sendRedirect("index.jsp");              } else {                  log.debug("登录失败，跳转到error.jsp页面");                  resp.sendRedirect("error.jsp");              }                        }                      }  

    |-- 测试

     运行项目，页面上出现如下图形验证码