JDBC的简单连接

对于传统的jdbc连接可以把它分为4个步骤：（当前以mysql数据库为例）

1.加载驱动程序

Class.forName("com.mysql.jdbc.Driver");//mysql的连接

//Class.forName("oracle.jdbc.driver.OralceDriver"); Oralce的连接

2.建立连接

conn = DriverManager.getConnection(url, username, password);

3.执行sql

private static void select(Connection conn, long id) throws SQLException {
    String sql = "SELECT id, username  FROM es_user WHERE id = ?";
    PreparedStatement ps = null;
    ResultSet rs = null;
    try {
        ps = conn.prepareStatement(sql);
        ps.setLong(1, id);
        rs = ps.executeQuery();
        while (rs.next()) {
            String userName = rs.getString(2);
            System.out.println("id=" + id + "userName=" + userName);
        }
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        rs.close();
        ps.close();
    }
}

4.关闭流

conn.close();
和

 rs.close();
 ps.close();

完整代码：

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

public class JDBCTest {
    static String url = "相应的地址";
    static String username = "username";
    static String password = "password";

    public static void main(String[] args) {
        connection();
    }

    private static void connection() {
        Connection conn = null;
        try {
            // 1.加载驱动程序
            Class.forName("com.mysql.jdbc.Driver");//mysql的连接
            //Class.forName("oracle.jdbc.driver.OralceDriver"); Oralce的连接
            //2.建立连接
            conn = DriverManager.getConnection(url, username, password);
            //3.执行sql
            select(conn, 1131117546905276417L);
            //4.关闭流
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static void select(Connection conn, long id) throws SQLException {
        String sql = "SELECT id, username  FROM es_user WHERE id = ?";
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            ps = conn.prepareStatement(sql);
            ps.setLong(1, id);
            rs = ps.executeQuery();
            while (rs.next()) {
                String userName = rs.getString(2);
                System.out.println("id=" + id + "userName=" + userName);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            rs.close();
            ps.close();
        }
    }
}