Javaee连接MySQL数据库实现注册登录

好的，下面是一个简单的Java EE项目，用于连接MySQL数据库实现注册登录功能。

首先，在MySQL数据库中创建一个名为“user”的表，包含以下字段：id、username、password。

然后，创建以下两个Java类：User和DBUtil。

User.java：

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

    public User(int id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public int getId() {
        return id;
    }

    public String getUsername() {
        return username;
    }

    public String getPassword() {
        return password;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

DBUtil.java：

import java.sql.*;

public class DBUtil {
    private static final String URL = "jdbc:mysql://localhost:3306/test?useSSL=false";
    private static final String USERNAME = "root";
    private static final String PASSWORD = "123456";

    public static Connection getConnection() {
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }

    public static void close(Connection conn, PreparedStatement pstmt, ResultSet rs) {
        try {
            if (rs != null) {
                rs.close();
            }
            if (pstmt != null) {
                pstmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

接下来，创建以下两个Servlet：RegisterServlet和LoginServlet。

RegisterServlet.java：

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

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

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "INSERT INTO user(username, password) VALUES (?, ?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, username);
            pstmt.setString(2, password);
            int result = pstmt.executeUpdate();
            if (result > 0) {
                out.print("注册成功！");
            } else {
                out.print("注册失败！");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt, null);
        }
    }
}

LoginServlet.java：

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

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

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "SELECT * FROM user WHERE username = ? AND password = ?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, username);
            pstmt.setString(2, password);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                out.print("登录成功！");
            } else {
                out.print("用户名或密码错误！");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, pstmt, rs);
        }
    }
}

最后，在web.xml文件中添加以下配置：

<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>

现在，你可以在Web页面上实现注册和登录功能了。