实验十一 Servlet(二)

【实验目的】
1．了解Servlet运行原理
2．掌握Servlet实现方式

【实验内容】
改造实验10，引入数据库，创建用户表，包括用户名和密码：客户端通过login.jsp发出登录请求，请求提交到loginServlet处理。如果用户名和密码跟用户表匹配则视为登录成功，跳转到loginSuccess.jsp页面，显示“欢迎你”+用户名；否则跳转到loginFail.jsp页面，显示“登录失败”，通过超链接返回login.jsp。
说明：把用户名和密码跟用户表匹配的功能放到loginServlet并实现相应请求转发或跳转即可。可以暂时不考虑创建其它java类。
login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body>
<form action="loginServlet" method="post"><label for="username">用户名：</label><input type="text" id="username" name="username" required><br><label for="password">密码：</label><input type="password" id="password" name="password" required><input type="submit" value="登陆">
</form>
</body>
</html>

loginServlet

package servlet;import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;import java.io.*;
import java.sql.*;
//使用@WebServlet注解
@WebServlet(name = "loginServlet" )
public class loginServlet extends HttpServlet {private static final String url = "jdbc:mysql://localhost:3306/test9";protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//从请求中获取用户名（stuId）和密码（stuPwd）String stuId = request.getParameter("username");String stuPwd = request.getParameter("password");try {// 加载和注册JDBC驱动Class.forName("com.mysql.jdbc.Driver");Connection conn = DriverManager.getConnection(url, "root", "123456");String sql = "select * from password where stuId = ? and stuPwd = ?";//创建PreparedStatement对象，这有助于防止SQL注入攻击PreparedStatement stmt = conn.prepareStatement(sql);//使用setString方法设置SQL查询中的参数值stmt.setString(1,stuId);stmt.setString(2,stuPwd);ResultSet rs = stmt.executeQuery();if (rs.next()) {//从结果集中获取用户名String stuname = rs.getString("stuId");//将用户名保存到会话中HttpSession session = request.getSession();session.setAttribute("username",stuname);//重定向到loginSuccess.jsp页面response.sendRedirect("loginSuccess.jsp");} else {//重定向到loginFail.jsp页面response.sendRedirect("loginFail.jsp");}rs.close();stmt.close();conn.close();} catch (SQLException se) {se.printStackTrace();} catch (Exception e) {e.printStackTrace();}}
}

loginSuccess.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>登陆成功</title>
</head>
<body><h4>欢迎你，${sessionScope.username}</h4>
</body>
</html>

loginFail.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>登陆失败</title>
</head>
<body><h4>登录失败</h4><a href="login.jsp">返回登陆页面</a>
</body>
</html>