JDBC连接数据库【MySql为例】

╰半夏微凉° 2022-02-09 09:45 287阅读 0赞

package com.example.demo.test;
    
    import com.mysql.jdbc.Driver;
    import org.junit.Test;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.SQLException;
    import java.util.Properties;
    
    /**
     * @author yhcookie
     * @date 2019/5/2 12:45
     */
    public class JDBCTest {
        /**
         * 每次都要new一个driver
         * @throws SQLException
         */
        @Test
        public void testJdbc01() throws SQLException {
            java.sql.Driver driver = new Driver();
            String url = "jdbc:mysql://localhost/zhyj";
            Properties info = new Properties();
            info.setProperty("user","root");
            info.setProperty("password","root");
            Connection connect = driver.connect(url, info);
            System.out.println(connect);
            connect.close();
        }
    
        /**
         * 利用java.sql.DriverManager来管理Driver
         * @throws SQLException
         */
        @Test
        public void testJdbc02() throws ClassNotFoundException, SQLException {
            /**
             * com.mysql.jdbc.Driver类静态代码块会用DriverManager管理Driver
             *     static {
                         try {
                            DriverManager.registerDriver(new Driver());
                         } catch (SQLException var1) {
                            throw new RuntimeException("Can't register driver!");
                         }
                     }
             */
            Class.forName("com.mysql.jdbc.Driver");//从JVM中找类模板，没有则加载
            Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/zhyj", "root", "root");
            System.out.println(connection);
            connection.close();
        }
    
        /**
         * 将参数写到properties文件中 提高适用性
         * @throws SQLException
         */
        @Test
        public void testJdbc03() throws SQLException, IOException, ClassNotFoundException {
            Properties info = new Properties();
            //将info.properties加载到Properties实例中
            ClassLoader classLoader = JDBCTest.class.getClassLoader();
            InputStream resourceAsStream = classLoader.getResourceAsStream("info.properties");
            info.load(resourceAsStream);
            String url = info.getProperty("url");
            String driverClass = info.getProperty("driverClass");
            String user = info.getProperty("user");
            String password = info.getProperty("password");
            //使用properties中的参数创建连接
            Class.forName(driverClass);
            Connection connection = DriverManager.getConnection(url, user, password);
            System.out.println(connection);
            connection.close();
        }
    }

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