Java实现简单登录注册功能 |21xrx.com

Java实现简单登录注册功能

2023-06-19 10:41:43 深夜i -- --

Java 登录注册功能

文章：在开发Web应用时，登录注册功能是必不可少的模块。本文将介绍如何使用Java编写一个简单的登录注册功能。首先，我们需要一个数据库用于存储用户信息，这里我们使用MySQL数据库，并创建一个名为"users"的表，表结构如下：


create table users (
  id int primary key auto_increment,
  username varchar(50) not null,
  password varchar(50) not null
);

然后，我们使用Java JDBC连接数据库，查询用户输入的用户名和密码是否匹配。代码如下：


import java.sql.*;
public class UserDao {
  private static final String URL = "jdbc:mysql://localhost:3306/test";
  private static final String USERNAME = "root";
  private static final String PASSWORD = "root";
  public boolean checkUser(String username, String password) throws SQLException {
    try (Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
       PreparedStatement statement = connection.prepareStatement("select count(*) from users where username=? and password=?")) {
      statement.setString(1, username);
      statement.setString(2, password);
      ResultSet resultSet = statement.executeQuery();
      resultSet.next();
      return resultSet.getInt(1) > 0;
    }
  }
  public boolean addUser(String username, String password) throws SQLException {
    try (Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
       PreparedStatement statement = connection.prepareStatement("insert into users (username,password) values (?,?)")) {
      statement.setString(1, username);
      statement.setString(2, password);
      int result = statement.executeUpdate();
      return result > 0;
    }
  }
}

以上代码中，checkUser方法用于检查用户名和密码是否匹配，addUser方法用于添加新用户。接下来，我们使用Servlet处理HTTP请求，实现登录和注册功能：

登录功能：


import java.io.IOException;
import java.sql.SQLException;
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 {
    String username = request.getParameter("username");
    String password = request.getParameter("password");
    UserDao userDao = new UserDao();
    try {
      if (userDao.checkUser(username, password)) {
        response.getWriter().append("登陆成功！");
      } else {
        response.getWriter().append("用户名或密码错误！");
      }
    } catch (SQLException e) {
      e.printStackTrace();
    }
  }
}

注册功能：


import java.io.IOException;
import java.sql.SQLException;
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 {
    String username = request.getParameter("username");
    String password = request.getParameter("password");
    UserDao userDao = new UserDao();
    try {
      if (userDao.addUser(username, password)) {
        response.getWriter().append("注册成功！");
      } else {
        response.getWriter().append("用户名已存在！");
      }
    } catch (SQLException e) {
      e.printStackTrace();
    }
  }
}

最后，在Web应用中配置以上代码，并启动应用，即可进行登录和注册功能操作。

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