Java web含验证码及权限登录实例代码

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; }}

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; }}

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();  } } /*public static void main(String[] args) {  DbUtil db=new DbUtil();  try {   db.getCon();   System.out.println("测试连接数据库，连接成功");  } catch (Exception e) {   // TODO Auto-generated catch block   e.printStackTrace();   System.out.println("测试连接数据库，连接失败");  } }*/}

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");   }  } } }

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(); } /*该方法主要作用是获得随机生成的颜色*/  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   /*将文字旋转制定角度*/   Graphics2D g2d_word=(Graphics2D)g;   AffineTransform trans=new AffineTransform();   trans.rotate((45)*3.14/180,15*i+8,7);   /*缩放文字*/   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 }}

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>web04</display-name> <welcome-file-list> <welcome-file>login.jsp</welcome-file>  <welcome-file>main.jsp</welcome-file> </welcome-file-list> <servlet>  <servlet-name>LoginServlet</servlet-name>  <servlet-class>com.ningmeng.web.LoginServlet</servlet-class> </servlet> <servlet> <description>输出验证码</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>PictureCheckCode</servlet-name> <servlet-class>com.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>

<%@ 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>

<%@ 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>

<%@ 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>