QueryRunner的无connection是怎样获得连接的???

Question

代码在下面已经给出 2 种方式查询到的结果一样,那么QueryRunner的无connection是怎样获得连接的???

//需要用到的工具类
public class DBCPUtils {
private static DataSource dataSource;
static{

    try {
        //1.加载找到properties文件输入流
        InputStream is = DBCPUtils.class.getClassLoader().getResourceAsStream("db.properties");
        //2.加载输入流
        Properties props = new  Properties();
        props.load(is);

        //3.创建数据源  基本数据源工厂
        dataSource = BasicDataSourceFactory.createDataSource(props);
    } catch (Exception e) {
        throw  new RuntimeException(e);
    }

}

public static DataSource getDataSource(){
    return dataSource;  
}

public static Connection getConnection6666(){
    try {
        return dataSource.getConnection();
    } catch (SQLException e) {
        throw  new RuntimeException(e);
    }

}

//有Connection 参数的
@Test
public void testQueryAll(){

    try {
        Connection conn = DBCPUtils.getConnection6666();
        QueryRunner qr = new QueryRunner(DBCPUtils.getDataSource());
        String sql = "select * from tbl_user";
        List<User> users = qr.query(conn, sql, new BeanListHandler<>(User.class));
        for (User user : users) {
            System.out.println(user.getUname()+"   "+user.getUpassword());
        }


    } catch (SQLException e) {
        throw new RuntimeException(e);

    }

//没有Connection 参数的
public void testQueryAll1(){

    try {
        QueryRunner qr = new QueryRunner(DBCPUtils.getDataSource());
       String sql = "select * from tbl_user";
        List<User> users = qr.query( sql, new BeanListHandler<>(User.class));

        for (User user : users) {
            System.out.println(user.getUname()+"   "+user.getUpassword());
        }


    } catch (SQLException e) {
        throw new RuntimeException(e);

    }

}

Answer 1

//需要用到的工具类
public class DBCPUtils {
    private static DataSource dataSource;
    static {
        try {
            //1.加载找到properties文件输入流
            InputStream is = DBCPUtils.class.getClassLoader().getResourceAsStream("db.properties");
            //2.加载输入流
            Properties props = new  Properties();
            props.load(is);
 
            //3.创建数据源  基本数据源工厂
            dataSource = BasicDataSourceFactory.createDataSource(props);
        } catch (Exception e) {
            throw  new RuntimeException(e);
        }
    }
 
    public static DataSource getDataSource(){
        return dataSource;  
    }
 
    public static Connection getConnection6666(){
        try {
            return dataSource.getConnection();
        } catch (SQLException e) {
            throw  new RuntimeException(e);
        }
    }
}
 
public class TestQuery {
    @Test
    public void testQueryAll(){
        try {
            Connection conn = DBCPUtils.getConnection6666();
            QueryRunner qr = new QueryRunner(DBCPUtils.getDataSource());
            String sql = "select * from tbl_user";
            List<User> users = qr.query(conn, sql, new BeanListHandler<>(User.class));
            for (User user : users) {
                System.out.println(user.getUname()+"   "+user.getUpassword());
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
 
    public void testQueryAll1(){
        try {
            QueryRunner qr = new QueryRunner(DBCPUtils.getDataSource());
            String sql = "select * from tbl_user";
            List<User> users = qr.query(sql, new BeanListHandler<>(User.class));
 
            for (User user : users) {
                System.out.println(user.getUname()+"   "+user.getUpassword());
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}