JSP动态实现web网页登陆和注册功能

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实现Web网页的登录和注册功能，涉及到前端页面的展示、后端逻辑处理以及数据库的交互。以下是使用JSP、Servlet和MySQL数据库实现登录和注册功能的基本步骤：1. 数据库设计首先，设计MySQL

实现Web网页的登录和注册功能，涉及到前端页面的展示、后端逻辑处理以及数据库的交互。以下是使用JSP、Servlet和MySQL数据库实现登录和注册功能的基本步骤：

1. 数据库设计

首先，设计MySQL数据库和用户表users。

CREATE TABLE users (
  id INT AUTO_INCREMENT PRIMARY KEY,
  username VARCHAR(50) UNIQUE NOT NULL,
  password VARCHAR(255) NOT NULL,
  email VARCHAR(100)
);

2. 创建注册页面（register.jsp）

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Register</title>
</head>
<body>
    <h2>Register</h2>
    <form action="RegisterServlet" method="post">
        <input type="text" name="username" placeholder="Username" required>
        <input type="email" name="email" placeholder="Email" required>
        <input type="password" name="password" placeholder="Password" required>
        <input type="submit" value="Register">
    </form>
</body>
</html>

3. 创建注册Servlet（RegisterServlet.java）

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.sql.*;

public class RegisterServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String email = request.getParameter("email");
        String password = request.getParameter("password");

        try {
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/your_database", "username", "password");
            String sql = "INSERT INTO users (username, email, password) VALUES (?, ?, ?)";
            PreparedStatement stmt = conn.prepareStatement(sql);
            stmt.setString(1, username);
            stmt.setString(2, email);
            stmt.setString(3, password); // 存储密码应使用哈希值，此处为简化示例

            int rowsInserted = stmt.executeUpdate();

            if (rowsInserted > 0) {
                response.sendRedirect("login.jsp"); // 重定向到登录页面
            } else {
                response.sendRedirect("register.jsp?error=true"); // 注册失败
            }

            stmt.close();
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
            throw new ServletException(e);
        }
    }
}

4. 创建登录页面（login.jsp）

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Login</title>
</head>
<body>
    <h2>Login</h2>
    <form action="LoginServlet" method="post">
        <input type="text" name="username" placeholder="Username" required>
        <input type="password" name="password" placeholder="Password" required>
        <input type="submit" value="Login">
    </form>
</body>
</html>

5. 创建登录Servlet（LoginServlet.java）

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.sql.*;

public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        try {
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/your_database", "username", "password");
            String sql = "SELECT * FROM users WHERE username = ? AND password = ?";
            PreparedStatement stmt = conn.prepareStatement(sql);
            stmt.setString(1, username);
            stmt.setString(2, password); // 应比较哈希值

            ResultSet rs = stmt.executeQuery();

            if (rs.next()) {
                HttpSession session = request.getSession();
                session.setAttribute("currentUser", username);
                response.sendRedirect("home.jsp"); // 用户主页
            } else {
                response.sendRedirect("login.jsp?error=true"); // 登录失败
            }

            rs.close();
            stmt.close();
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
            throw new ServletException(e);
        }
    }
}

6. 配置web.xml

确保你的Servlet映射正确配置在web.xml文件中。

<servlet>
    <servlet-name>RegisterServlet</servlet-name>
    <servlet-class>RegisterServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>RegisterServlet</servlet-name>
    <url-pattern>/register</url-pattern>
</servlet-mapping>

<servlet>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/login</url-pattern>
</servlet-mapping>