1.新建web项目，修改index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <script type="text/javascript"> function reloadCode(){ var time = new Date().getTime(); document.getElementById("codeImage").src="<%=request.getContextPath()%>/servlet/ImageServlet?d="+time; } </script> <body> <form action="<%=request.getContextPath()%>/servlet/loginServlet" method="post"> <input type="text" name="checkCode"> <input type="submit" value="提交"> </form> <img name="codeImage" alt="验证码" src="<%=request.getContextPath()%>/servlet/ImageServlet"> <a href="javascript:reloadCode();">换一张</a> </body> </html>
2.生成图片的servlet
package com.servlet; import java.awt.Color; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import java.io.PrintWriter; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ImageServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } //生成图片 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { BufferedImage bi=new BufferedImage(68, 22, BufferedImage.TYPE_INT_RGB);//创建图片 Graphics g = bi.getGraphics();//获取画笔 g.setColor(Color.LIGHT_GRAY);//设置画笔颜色 g.fillRect(0, 0, 68, 22);//填充背景 char[] ch="ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890".toCharArray();//字符库 Random r=new Random(); StringBuilder sb=new StringBuilder(); for(int i=0;i<4;i++){ int index=r.nextInt(ch.length);//随机获取一个字符库里的字符库下标 g.setColor(new Color(r.nextInt(100), r.nextInt(150), r.nextInt(250)));//给画笔设置随机颜色 g.drawString(ch[index]+"", (i*15)+3, 15);//画刚才字符串下标的字符 sb.append(ch[index]);//拼接，记录生成的字符内容 } request.getSession().setAttribute("piccode", sb.toString()); ImageIO.write(bi, "jpg", response.getOutputStream()); } }
3.登录验证
package com.servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class LoginServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); String userCode = request.getParameter("checkCode");//用户提交的字符串 String imageCode=request.getSession().getAttribute("piccode").toString();//正确的字符串 System.out.println(userCode+" "+imageCode); PrintWriter out = response.getWriter(); try { if(userCode.toUpperCase().equals(imageCode)){//只要用户输入的正确(不论大小写) out.print("验证码正确"); }else{ out.print("验证码错误"); } } catch (Exception e) { // TODO: handle exception }finally{ out.flush(); out.close(); } } }
4.配置servlet
<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <servlet> <servlet-name>ImageServlet</servlet-name> <servlet-class>com.servlet.ImageServlet</servlet-class> </servlet> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>com.servlet.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ImageServlet</servlet-name> <url-pattern>/servlet/ImageServlet</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/servlet/loginServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
5.项目源码
链接：https://pan.baidu.com/s/1mkh6f8k 密码：ie6z