用户登录验证
1.案例需求：
1.访问带有验证码的登录页面login.jsp
2.用户输入用户名，密码以及验证码
* 如果用户名和密码输入有误，跳转登录页面，提示：用户名或密码错误
* 如果验证码输入有误，跳转登录页面，提示：验证码错误
* 如果全部输入正确，则跳转到主页success.jsp，显示：用户名，欢迎您
代码如下
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>login</title>
<script>
window.onload=function () {
document.getElementById("img").onclick=function () {
this.src="/08__war_exploded/CheckCodeServlet?time="+new Date().getTime();
}
}
</script>
<style>
div{
color:red;
}
</style>
</head>
<body>
<form action="/08__war_exploded/loginServlet" method="post">
<table>
<tr>
<td>用户名</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>密码</td>
<td><input type="password" name="password"></td>
</tr>
<tr>
<td>验证码</td>
<td><input type="text" name="checkCode"></td>
</tr>
<tr>
<td colspan="2"><img id="img" src="/08__war_exploded/CheckCodeServlet"></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="登录"></td>
</tr>
</table>
</form>
<div><%=request.getAttribute("cc_error")==null?"":request.getAttribute("cc_error")%></div>
<div><%=request.getAttribute("login_error")==null?"":request.getAttribute("login_error")%></div>
</body>
</html>
success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1><%= request.getSession().getAttribute("user")%>,欢迎您</h1>
</body>
</html>
session
package cn.itcast.servlet;
import cn.itcast.entity.UserDao;
import cn.itcast.respository.UserRespository;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
@WebServlet("/loginServlet")
public class loginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置request编码
request.setCharacterEncoding("utf-8");
//获取参数
String username=request.getParameter("username");
String password=request.getParameter("password");
String checkCode=request.getParameter("checkCode");
//封装对象
UserDao loginUser=new UserDao();
loginUser.setUsername(username);
loginUser.setPassword(password);
// 实例化一个StudentResponsitory对象
UserRespository userd = new UserRespository();
String usernameone=userd.getList().getUsername();
String passwordone=userd.getList().getPassword();
// //判断userd
// if(userd==null){
// //登录失败
// request.getRequestDispatcher("/failServlet").forward(request,response);
// }else{
// //登录成功
// //存储数据
// request.setAttribute("userd",userd);
// //转发
// request.getRequestDispatcher("/successServlet").forward(request,response);
// }
// System.out.println("--------------1---------------");
// System.out.println(usernameone);
// System.out.println("---------------2--------------");
// System.out.println(passwordone);
// System.out.println("---------------3--------------");
// System.out.println(userd.QueryAll());
// System.out.println("---------------4--------------");
// System.out.println(userd.getList().get(0).getUsername());
// System.out.println("---------------5--------------");
// System.out.println(userd.getList().get(0).getPassword());
// System.out.println("---------------6--------------");
//获取checkCode_session
HttpSession session=request.getSession();
String checkCode_session=(String) session.getAttribute("checkCode_session");
//删除session中存储的验证码
session.removeAttribute("checkCode_session");
//先判断验证码是否正确
if(checkCode_session!=null && checkCode_session.equalsIgnoreCase(checkCode)){
//忽略大小写比较
//验证码正确
//判断用户名和密码是否一致
if(usernameone.equals(username)&&passwordone.equals(password)){
//需要调用数据库来进行操作
//登录成功
//存储信息，用户信息
session.setAttribute("user",username);
//重定向到success.jsp
response.sendRedirect(request.getContextPath()+"/success.jsp");
}else{
//登录失败
//存储提示信息到request
request.setAttribute("login_error","用户名或者密码错误");
//转发到登录页面
request.getRequestDispatcher("/login.jsp").forward(request,response);
}
}else{
//验证码不一致
//存储提示信息到request
request.setAttribute("cc_error","验证码错误");
//转发到登录页面
request.getRequestDispatcher("/login.jsp").forward(request,response);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
验证码设计
package cn.itcast.servlet;
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;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet("/CheckCodeServlet")
public class CheckCodeServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width = 100;
int height = 50;
//创建一对象，在内存中图片（验证码图片对象）
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//美化图片
//2.1.填充背景色
Graphics g = image.getGraphics();//画笔对象
g.setColor(Color.pink);//设置画笔颜色
g.fillRect(0, 0, width, height);
//2.2.画边框
g.setColor(Color.BLUE);
g.drawRect(0, 0, width - 1, height - 1);
String str = "ABCDEFGHIJKLMNOPQRSTOVWXYZabcdefghijklmnopqrstovwxyz";
//生成随机角标
Random ran = new Random();
StringBuilder sb=new StringBuilder();
for (int i = 1; i <= 4; i++) {
int index = ran.nextInt(str.length());
//获取字符
char ch = str.charAt(index);//随机字符
sb.append(ch);
g.drawString(ch + "", width / 5 * i, height / 2);
//2.3.写验证码
}
String checkCode_session=sb.toString();
//将验证码存入session
request.getSession().setAttribute("checkCode_session",checkCode_session);
//2.4画干扰线
g.setColor(Color.GREEN);
for (int i = 0; i <= 4; i++) {
int x1 = ran.nextInt(width);
int x2 = ran.nextInt(width);
int y1 = ran.nextInt(height);
int y2 = ran.nextInt(height);
g.drawLine(x1, x1, x2, y2);
}
//将图片输出到页面显示
ImageIO.write(image, "jpg", response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}