JSP注册登录实现方法

JSP注册登录的实现方法通常包括以下步骤：

1. 创建数据库表格：创建一个用户表，包含用户名、密码等字段。

2. 编写JSP页面：创建一个注册页面和一个登录页面，分别包含表单元素和提交按钮。

3. 编写Servlet：将表单数据传递到Servlet中进行处理，包括注册和登录的逻辑处理。

4. 编写JavaBean：创建一个用户类，包含用户名、密码等属性。

5. 编写DAO类：创建一个数据访问对象类，用于连接数据库，并且提供方法实现用户数据的增删改查。

6. 配置web.xml：将Servlet和JSP页面映射到web.xml文件中。

7. 测试：运行程序，在浏览器中输入网址，进行注册和登录的测试。

下面是一个简单的JSP注册登录的实现代码示例：

1. 创建用户表

CREATE TABLE user (
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(50) NOT NULL,
password VARCHAR(50) NOT NULL
);

2. 编写JSP页面

注册页面register.jsp

<form action="registerServlet" method="post">
    <input type="text" name="username" placeholder="请输入用户名">
    <input type="password" name="password" placeholder="请输入密码">
    <button type="submit">注册</button>
</form>

登录页面login.jsp

<form action="loginServlet" method="post">
    <input type="text" name="username" placeholder="请输入用户名">
    <input type="password" name="password" placeholder="请输入密码">
    <button type="submit">登录</button>
</form>

3. 编写Servlet

注册Servlet RegisterServlet.java

package com.example.servlet;

import java.io.IOException;
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 com.example.bean.User;
import com.example.dao.UserDao;

@WebServlet("/registerServlet")
public class RegisterServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

        User user = new User(username, password);
        UserDao userDao = new UserDao();
        boolean result = userDao.addUser(user);

        if (result) {
            response.sendRedirect("login.jsp");
        } else {
            response.sendRedirect("error.jsp");
        }
    }
}

登录Servlet LoginServlet.java

package com.example.servlet;

import java.io.IOException;
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 com.example.bean.User;
import com.example.dao.UserDao;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

        UserDao userDao = new UserDao();
        User user = userDao.getUser(username, password);

        if (user != null) {
            request.getSession().setAttribute("user", user);
            response.sendRedirect("welcome.jsp");
        } else {
            response.sendRedirect("error.jsp");
        }
    }
}

4. 编写JavaBean

User.java

package com.example.bean;

public class User {
    private int id;
    private String username;
    private String password;

    public User() {
    }

    public User(String username, String password) {
        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;
    }
}

5. 编写DAO类

UserDao.java

package com.example.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import com.example.bean.User;
import com.example.util.DBUtil;

public class UserDao {
    private Connection conn = null;
    private PreparedStatement ps = null;
    private ResultSet rs = null;

    public boolean addUser(User user) {
        String sql = "INSERT INTO user (username, password) VALUES (?, ?)";

        try {
            conn = DBUtil.getConnection();
            ps = conn.prepareStatement(sql);
            ps.setString(1, user.getUsername());
            ps.setString(2, user.getPassword());
            int result = ps.executeUpdate();
            if (result > 0) {
                return true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.closeAll(conn, ps, rs);
        }
        return false;
    }

    public User getUser(String username, String password) {
        String sql = "SELECT * FROM user WHERE username = ? AND password = ?";

        try {
            conn = DBUtil.getConnection();
            ps = conn.prepareStatement(sql);
            ps.setString(1, username);
            ps.setString(2, password);
            rs = ps.executeQuery();
            if (rs.next()) {
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("username"));
                user.setPassword(rs.getString("password"));
                return user;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.closeAll(conn, ps, rs);
        }
        return null;
    }
}

6. 配置web.xml

<?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>jsp-login-demo</display-name>
    <welcome-file-list>
        <welcome-file>welcome.jsp</welcome-file>
    </welcome-file-list>
    <servlet>
        <servlet-name>registerServlet</servlet-name>
        <servlet-class>com.example.servlet.RegisterServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>loginServlet</servlet-name>
        <servlet-class>com.example.servlet.LoginServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>registerServlet</servlet-name>
        <url-pattern>/registerServlet</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>loginServlet</servlet-name>
        <url-pattern>/loginServlet</url-pattern>
    </servlet-mapping>
</web-app>

7. 测试

运行程序，在浏览器中输入注册页面的网址，输入用户名和密码，点击注册按钮，注册成功后跳转到登录页面，输入正确的用户名和密码，点击登录按钮，跳转到欢迎页面，表示登录成功。