所用到的开发工具为myeclipse10，MySQL数据库。

首先，在myeclipse中新建一个Java web项目。

项目的结构：

数据库结构：

下面将各个包中的代码粘贴出来。

com.ningmeng.dao包

package com.ningmeng.dao;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import com.ningmeng.model.User;public class UserDao { public User login(Connection con,User user) throws SQLException{ User resultUser=null; String sql="select * from user where username=? and password=?"; PreparedStatement ps=con.prepareStatement(sql);// ps.setString(1, user.getUsername()); ps.setString(2, user.getPassword()); ResultSet rs=ps.executeQuery(); if(rs.next()){ resultUser=new User(); resultUser.setUsername(rs.getString("username")); resultUser.setPassword(rs.getString("password")); } return resultUser; }}

com.ningmeng.model包

package com.ningmeng.model;public class User { private int id; private String username; private String password; public User() { super(); } public User(String username, String password) { super(); this.username = username; this.password = password; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; }}

com.ningmeng.util包

package com.ningmeng.util;import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException; public class DbUtil { private String url="jdbc:mysql://localhost:3306/db-jsp"; private String user="root"; private String password="123"; private String driver="com.mysql.jdbc.Driver"; public Connection getCon() throws Exception{ Class.forName(driver); Connection con=DriverManager.getConnection(url, user, password); return con; } public static void getClose(Connection con) throws SQLException{ if(con!=null){ con.close(); } } }

com.ningmeng.web包

package com.ningmeng.web;import java.io.IOException;import java.sql.Connection;import java.io.*;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import javax.servlet.http.*;import com.ningmeng.dao.UserDao;import com.ningmeng.model.User;import com.ningmeng.util.DbUtil;public class LoginServlet extends HttpServlet{ DbUtil db=new DbUtil(); UserDao userDao=new UserDao(); /** * */ private static final long serialVersionUID = 1L; @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String username=request.getParameter("username"); String password=request.getParameter("password"); String checkcode=request.getParameter("checkCode"); HttpSession session=request.getSession(); //session.getAttribute("randCheckCode"); String s = (String)session.getAttribute("randCheckCode"); if(!checkcode.equals(s)) { response.sendRedirect("linmao.jsp"); }else{ if(request.getParameter("ra").equals("l")){ Connection con=null; try { User user=new User(username,password); con=db.getCon(); User currentUser=userDao.login(con, user); if(currentUser==null){ //System.out.println("no"); request.setAttribute("error", "用户名或者密码错误"); request.setAttribute("username", username); request.setAttribute("password", password); request.getRequestDispatcher("login.jsp").forward(request, response); }else{ //System.out.println("yes"); HttpSession session1=request.getSession(); session1.setAttribute("currentUser",currentUser); response.sendRedirect("main.jsp"); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } else{ response.sendRedirect("linmao.jsp"); } } } }

com.servlet包

package com.servlet;import java.awt.*;import java.awt.geom.*;import java.awt.image.*;import java.io.*;import java.util.*;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import javax.imageio.ImageIO;public class PictureCheckCode extends HttpServlet { private static final long serialVersionUID = 1L; public PictureCheckCode() { super(); } public void destroy() { super.destroy(); } public void init() throws ServletException { super.init(); } public Color getRandColor(int s,int e){ Random random=new Random (); if(s>255) s=255; if(e>255) e=255; int r,g,b; r=s+random.nextInt(e-s); //随机生成RGB颜色中的r值 g=s+random.nextInt(e-s); //随机生成RGB颜色中的g值 b=s+random.nextInt(e-s); //随机生成RGB颜色中的b值 return new Color(r,g,b); } @Override public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置不缓存图片 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "No-cache"); response.setDateHeader("Expires", 0); //指定生成的响应图片,一定不能缺少这句话,否则错误. response.setContentType("image/jpeg"); int width=86,height=33; //指定生成验证码的宽度和高度 BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //创建BufferedImage对象,其作用相当于一图片 Graphics g=image.getGraphics(); //创建Graphics对象,其作用相当于画笔 Graphics2D g2d=(Graphics2D)g; //创建Grapchics2D对象 Random random=new Random(); Font mfont=new Font("楷体",Font.BOLD,20); //定义字体样式 g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height); //绘制背景 g.setFont(mfont); //设置字体 g.setColor(getRandColor(180,200)); //绘制100条颜色和位置全部为随机产生的线条,该线条为2f for(int i=0;i<100;i++){ int x=random.nextInt(width-1); int y=random.nextInt(height-1); int x1=random.nextInt(6)+1; int y1=random.nextInt(12)+1; BasicStroke bs=new BasicStroke(2f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL); //定制线条样式 Line2D line=new Line2D.Double(x,y,x+x1,y+y1); g2d.setStroke(bs); g2d.draw(line); //绘制直线 } //输出由英文，数字，和中文随机组成的验证文字，具体的组合方式根据生成随机数确定。 String sRand=""; String ctmp=""; int itmp=0; //制定输出的验证码为四位 for(int i=0;i<4;i++){ switch(random.nextInt(3)){ case 1: //生成A-Z的字母 itmp=random.nextInt(26)+65; ctmp=String.valueOf((char)itmp); break; default: itmp=random.nextInt(10)+48; ctmp=String.valueOf((char)itmp); break; } sRand+=ctmp; Color color=new Color(20+random.nextInt(110),20+random.nextInt(110),random.nextInt(110)); g.setColor(color); //将生成的随机数进行随机缩放并旋转制定角度 PS.建议不要对文字进行缩放与旋转,因为这样图片可能不正常显示 Graphics2D g2d_word=(Graphics2D)g; AffineTransform trans=new AffineTransform(); trans.rotate((45)*3.14/180,15*i+8,7); float scaleSize=random.nextFloat()+0.8f; if(scaleSize>1f) scaleSize=1f; trans.scale(scaleSize, scaleSize); g2d_word.setTransform(trans); g.drawString(ctmp, 15*i+18, 14); } HttpSession session=request.getSession(true); session.setAttribute("randCheckCode", sRand); g.dispose(); //释放g所占用的系统资源 ImageIO.write(image,"JPEG",response.getOutputStream()); //输出图片 }}

配置web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://.servlet.PictureCheckCode</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/login</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>PictureCheckCode</servlet-name> <url-pattern>/PictureCheckCode</url-pattern> </servlet-mapping></web-app>

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><script language="javascript">function myReload() { document.getElementById("CreateCheckCode").src = document .getElementById("CreateCheckCode").src + "?nocache=" + new Date().getTime();}</script></head><body><form action="login" method="post"> <table> <tr> <th colspan="2">登录界面</th> </tr> <tr> <td>账号：</td> <td><input type="text" id="username" name="username" value="${username}"></td> </tr> <tr> <td>密码：</td> <td><input type="password" id="password" name="password" value="${password}"></td> </tr> <tr> <td>验证码：</td> <td><input name="checkCode" type="text" id="checkCode" title="验证码区分大小写" size="8" ,maxlength="4" /> <img src="PictureCheckCode" id="CreateCheckCode" align="middle"> <a href="" onclick=" rel="external nofollow" myReload()"> 看不清,换一个</a> </tr> <tr> <td>类型：</td> <td> <input type="radio" name="ra" value="l" checked="checked"/>一般研究人员 <input type="radio" name="ra" value="m" />管理员研究人员 </td> </tr> <tr> <td> <input type="submit" value="提交"> <font color="red">${error}</font> </td> </tr> </table></form></body></html>

main.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><p>登录成功</p>当前用户：${currentUser.username}<br/>当前密码：${currentUser.password}<br/></body></html>

linmao.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%><%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%>" rel="external nofollow" > <title>My JSP 'linmao.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" rel="external nofollow" > --> </head> <body> This is my JSP page. <br> </body></html>

项目现在做到验证码和权限这一块，找回密码功能还没有做完，结构中Check.jsp还用不到。还有连接数据库的操作，就不详细叙述了。

账号和密码在数据库的表中

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