手写JDBC - 数据库、驱动信息存储在配置文件

1. 将数据库、驱动信息存储在配置文件

configure.properties

 url=jdbc:mysql://localhost:3306/数据库名?serverTimezone=GMT&useSSL=false
 user=用户名，一般是root
 password=数据库密码
 driver=com.mysql.cj.jdbc.Driver

2. JDBC工具类

MyDBUtil.java

 import java.io.InputStream;
 import java.sql.*;
 import java.util.Properties;

 /**
  * 手写实现JDBC工具类
  * @author Nemo
  * @version 1.0
  * @date 2019/4/10
  */
 public class MyDBUtil {
     private static String url;
     private static Properties proterties;

     // 注册驱动
     static {
         proterties = new Properties;

         InputStream configureStream = MyDBUtil.class.getClassLoader.getResourceAsStream("configure.proterties");
         try {
             properties.load(configureStream);
             String driver = properties.getProperty("driver");
             class.forName(driver);

             url = properties.getProperty("url");
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

     // 获取连接
     public static Connection getConnection() throw SQLException{
         return DriverManager.getConnection(url, properties);
     }

     // 释放资源
     public static void release(Statement statement, Connection connection, ResultSet resultSet) {
         closeQuietly(statement);
         closeQuietly(connection);
         closeQuietly(resultSet);
     }
     // 重载释放资源
     public static void release(Statement statement, Connection connection) {
         closeQuietly(statement);
         closeQuietly(connection);
     }

     private static void closeQuietly(AutoCloseable closeable) {
         if (closeable != null) {
             try {
                 closeable.close();
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }
     }
 }

3. 以实现数据库事务为例，演示工具类的使用

TranctionTest.java

 import org.junit.Test;

 import java.sql.Connection;
 import java.sql.SQLException;
 import java.sql.Savepoint;
 import java.sql.Statement;

 /**
  * 以数据库事务为例进行演示
  * @author Nemo
  * @version 1.0
  * @date 2019/4/13
  */
 public class TranctionTest {
     @Test
     public void traction() throws SQLException {
         Connection conn = null;
         Statement stm = null;
         Savepoint savepoint = null;
         try {
             // 获取数据库连接
             conn = MyDBUtil.getConnection();

             // 关闭数据库自动commit功能
             conn.setAutoCommit(false);

             // 建立sql语句
             stm = conn.cteateStatement();

             // zs给lisi转账100
             String sql1 = "update user set money=money-100 where name='zs';";
             String sql2 = "update user set money=money+100 where name='lisi';";

             // wangwu给lisi转账100
             String sql3 = "update user set money=money-100 where name='wangwu';";
             String sql4 = "update user set money=money+100 where name='lisi';";

             // 提交sql语句
             stm.executeUpdate(sql1);
             stm.executeUpdate(sql2);

             // 设置savepoint
             savepoint = conn.setSavepoint();

             int i = 1/0;

             stm.executeUpdate(sql3);
             stm.executeUpdate(sql4);

             conn.commit();
         } catch (Exception e) {
             conn.rollback(savepoint);
             conn.commit();
         } finally {
             MyDBUtil.release(statement, connection);
         }
     }
 }