Java jdbc增删查改

以下是Java JDBC实现增删改查的示例代码：

1. 连接数据库

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBUtil {
    private static final String URL = "jdbc:mysql://localhost:3306/test";
    private static final String USER = "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, USER, PASSWORD);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
}

2. 实现数据库的查询

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

public class UserDao {
    public User getUserById(int id) {
        User user = null;
        Connection conn = DBUtil.getConnection();
        String sql = "select * from user where id=?";
        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1, id);
            ResultSet rs = ps.executeQuery();
            if (rs.next()) {
                user = new User();
                user.setId(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setAge(rs.getInt("age"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return user;
    }
}

3. 实现数据库的删除

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

public class UserDao {
    public boolean deleteUserById(int id) {
        Connection conn = DBUtil.getConnection();
        String sql = "delete from user where id=?";
        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1, id);
            int result = ps.executeUpdate();
            if (result > 0) {
                return true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return false;
    }
}

4. 实现数据库的增添

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

public class UserDao {
    public boolean addUser(User user) {
        Connection conn = DBUtil.getConnection();
        String sql = "insert into user(name, age) values(?, ?)";
        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1, user.getName());
            ps.setInt(2, user.getAge());
            int result = ps.executeUpdate();
            if (result > 0) {
                return true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return false;
    }
}

5. 实现数据库数据的修改

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

public class UserDao {
    public boolean updateUser(User user) {
        Connection conn = DBUtil.getConnection();
        String sql = "update user set name=?, age=? where id=?";
        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1, user.getName());
            ps.setInt(2, user.getAge());
            ps.setInt(3, user.getId());
            int result = ps.executeUpdate();
            if (result > 0) {
                return true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return false;
    }
}