手写JDBC

步骤

1. 加载数据库驱动

2. 创建数据库连接

3. 创建Preparedstatement

4. 执行查询或更新语句

5. 处理结果

6. 关闭资源

代码实现

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
 
public class JdbcExample {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/mydatabase";
        String user = "user";
        String password = "password";
 
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
 
        try {
            // 加载MySQL JDBC驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
 
            // 建立连接
            conn = DriverManager.getConnection(url, user, password);
 
            // 创建PreparedStatement
            String sql = "SELECT * FROM mytable WHERE id = ?";
            pstmt = conn.prepareStatement(sql);
 
            // 设置参数
            pstmt.setInt(1, 1);
 
            // 执行查询
            rs = pstmt.executeQuery();
 
            // 处理结果
            while (rs.next()) {
                System.out.println(rs.getString("columnname"));
            }
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭资源
            try {
                if (rs != null) {
                    rs.close();
                }
                if (pstmt != null) {
                    pstmt.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}