1.JDBC体系系统 一组规范：接口
- JDBC接口（API）包括两个层次：
- 面向应用的API：Java API，抽象接口，供应用开发人员使用（连接数据库，执行SQL语句，获得结果）
- 面向数据库的API：Java Driver API，供开发商开发数据库驱动程序
JDBC是sun公司提供一套用于数据库操作的接口，java程序员只需要面向这套接口编程即可。
不同的数据库供应商需要为这组接口提供不同的实现集，即不同数据库的驱动程序。[En]
Different database vendors need to provide different implementation sets for this set of interfaces, that is, drivers for different databases.
package com.aiguigu.connection;
import org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
public class ConnectionTest {
@Test
public void testConnection1() throws SQLException {
Driver driver = new com.mysql.cj.jdbc.Driver();
//jdbc：mysql协议
//local：IP地址
//3306：默认mysql端口号
//test：test数据库
String url = "jdbc:mysql://localhost:3306/MYSQL?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT";
//将用户名和密码封装在properties中
Properties info = new Properties();
info.setProperty("user","root");
info.setProperty("password","1234");
Connection conn = driver.connect(url, info);
System.out.println(conn);
}
//方式二：对方式一的迭代 在如下的方式中不出现第三方API，使程序具有更好的可移植性
@Test
public void testConnection2() throws Exception {
//获取Driver实现类对象，使用反射
Class clazz = Class.forName("com.mysql.cj.jdbc.Driver");
Driver driver = (Driver) clazz.newInstance();
//2.提供要连接的数据库
String url = "jdbc:mysql://localhost:3306/MYSQL?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT";
//提供要连接的用户名和密码
Properties info = new Properties();
info.setProperty("user","root");
info.setProperty("password","1234");
//获取连接
Connection conn = driver.connect(url, info);
System.out.println(conn);
}
@Test
//方式三：使用DriverManager替换Driver
public void testConnection3() throws Exception {
//1.获取Drive实现类的对象
Class clazz = Class.forName("com.mysql.cj.jdbc.Driver");
Driver driver = (Driver) clazz.newInstance();
//2提供另外三个连接的基本信息
String url = "jdbc:mysql://localhost:3306/MYSQL?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT";
String user = "root";
String password = "1234";
//注册驱动
DriverManager.registerDriver(driver);
//获取连接
Connection connection = DriverManager.getConnection(url, user, password);
System.out.println(connection);
}
@Test
//方式三：使用DriverManager替换Driver
public void testConnection4() throws Exception {
//1.提供另外三个连接的基本信息
String url = "jdbc:mysql://localhost:3306/MYSQL?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT";
String user = "root";
String password = "1234";
//2.获取Drive实现类的对象
Class.forName("com.mysql.cj.jdbc.Driver");
//相较于方式三可以省略如下操作：
// Driver driver = (Driver) clazz.newInstance();
// //注册驱动
// DriverManager.registerDriver(driver);
//3.获取连接
Connection connection = DriverManager.getConnection(url, user, password);
System.out.println(connection);
}
//方式五：将数据库连接的四个基本信息声明在配置文件中通过读取配置文件，获取连接
@Test
public void getConnection5() throws Exception {
//1.读取配置文件中4个基本信息
InputStream is = ConnectionTest.class.getClassLoader().getResourceAsStream("jdbc.properties");
Properties pros = new Properties();
pros.load(is);
String user = pros.getProperty("user");
String password = pros.getProperty("password");
String url = pros.getProperty("url");
String driverClass = pros.getProperty("driverClass");
//加载驱动
Class.forName(driverClass);
//获取连接
Connection conn = DriverManager.getConnection(url, user, password);
System.out.println(conn);
}
}
Original: https://www.cnblogs.com/heyiyuanqi/p/16578096.html
Author: 何以媛起
Title: 0811JDBC随笔
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