JDBC——段階的総括

1、JDBCワークフロー

jar依存を追加  

Class.forName(「駆動」)

Connection con=DriverManager.getConnection(url,username,pwd);

PrepareStatement ps=con.PrepareStatement(sql);        Ps.setString(1,””);

Insert update  delete--- int ret=ps.executeUpdate();        Select             ---ResultSet rs=ps.executeQuery();

結果セットResultSet

を巡回

リソースを閉じてから作成された

を閉じます.
2、工具類を封入した

public class DruidUtils {
    private static DruidDataSource dataSource=null;

    private static ThreadLocal threadLocal;

    static{
        //1    
        try {

            threadLocal=new ThreadLocal<>();

            InputStream is = DruidUtils.class.getClassLoader().getResourceAsStream("database.properties");
            Properties properties=new Properties();
            properties.load(is);

            dataSource= (DruidDataSource) DruidDataSourceFactory.createDataSource(properties);
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("        ....");
            //  
        }

    }
     

    //     
    public static DataSource getDataSource(){
        return dataSource;
    }


    //    
    public static Connection getConnection() throws SQLException {
        Connection conn=threadLocal.get(); //Thread.curentThread;
        if(conn==null){
            conn=dataSource.getConnection();
            //  threadLocal
            threadLocal.set(conn);

        }
        return  conn;
    }


    //    
    public static void beginTransaction() throws  SQLException{
        Connection conn = getConnection();
        conn.setAutoCommit(false);

    }

    //    
    public static void commit() throws SQLException{
        Connection conn = getConnection();
        conn.commit();
    }

    //    
    public static void roolback() throws SQLException{
        Connection conn = getConnection();
        conn.rollback();
    }

    //  
    public static void close() throws SQLException{
        Connection conn = getConnection();
        conn.close();
        threadLocal.remove();

    }

}

        3、データソース、接続プール
           Druid c3p0
階層開発利用MVCモード:dao  service  controllers