【JDBC】连接数据库的几种方式

比眉伴天荒 2021-09-24 14:10 338阅读 0赞

以mysql连接为例

引入驱动

<dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.38</version>
        
    </dependency>

junit泰马

package xyz.hashdog.jdbc;
    
    import org.junit.Test;
    
    import java.sql.Connection;
    import java.sql.Driver;
    import java.sql.DriverManager;
    import java.sql.SQLException;
    import java.util.Properties;
    
    public class ConnectionTest {
    
    
        /**
         * 1.通过驱动实现类获取
         * @throws SQLException
         */
        @Test
        public  void  testConnection1() throws SQLException {
            Driver driver = new com.mysql.jdbc.Driver();
            String url = "jdbc:mysql://localhost:3306/st-jdbc";
            Properties info = new Properties();
            info.setProperty("user","root");
            info.setProperty("password","hashdog2019");
            Connection conn = driver.connect(url,info);
            System.out.println(conn);
    
        }
    
        /**
         * 2.通过反射获取
         * @throws ClassNotFoundException
         * @throws IllegalAccessException
         * @throws InstantiationException
         * @throws SQLException
         */
        @Test
        public void testConnection2() throws ClassNotFoundException, IllegalAccessException, InstantiationException, SQLException {
            //反射方式获取Driver实现类,可以根据驱动包名切换
            Class<?> clazz = Class.forName("com.mysql.jdbc.Driver");
            Driver driver = (Driver)clazz.newInstance();
            String url = "jdbc:mysql://localhost:3306/st-jdbc";
            Properties info = new Properties();
            info.setProperty("user","root");
            info.setProperty("password","hashdog2019");
            Connection conn = driver.connect(url,info);
            System.out.println(conn);
    
        }
    
    
        /**
         * 3.DriverManager替换Driver
         * @throws ClassNotFoundException
         * @throws IllegalAccessException
         * @throws InstantiationException
         * @throws SQLException
         */
        @Test
        public void testConnection3() throws ClassNotFoundException, IllegalAccessException, InstantiationException, SQLException {
            //1.获取Driver实现类
            Class<?> clazz = Class.forName("com.mysql.jdbc.Driver");
            Driver driver = (Driver)clazz.newInstance();
            //2.提供基本信息
            String url = "jdbc:mysql://localhost:3306/st-jdbc";
            String user = "root";
            String password = "hashdog2019";
    
            //3.注册驱动
            DriverManager.registerDriver(driver);
            //获取连接
            Connection connection = DriverManager.getConnection(url, user, password);
            System.out.println(connection);
    
        }
    
    
        /**
         * 4.优化方式三,加载驱动会自动注册
         * @throws ClassNotFoundException
         * @throws IllegalAccessException
         * @throws InstantiationException
         * @throws SQLException
         */
        @Test
        public void testConnection4() throws ClassNotFoundException, IllegalAccessException, InstantiationException, SQLException {
            //1.提供基本信息
            String url = "jdbc:mysql://localhost:3306/st-jdbc";
            String user = "root";
            String password = "hashdog2019";
    
            //2.获取Driver实现类
            Class.forName("com.mysql.jdbc.Driver");
    //        Driver driver = (Driver)clazz.newInstance();
    //        DriverManager.registerDriver(driver);
            //获取连接
            Connection connection = DriverManager.getConnection(url, user, password);
            System.out.println(connection);
    
        }
    }