数据库dbutils

public void fun1() throws SQLException {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "insert into t_stu values(?,?,?,?)";
        Object[] params = {1002, "liSi", 88, "female"};
        
        qr.update(sql, params);
    }
    
    @Test
    public void fun2() throws SQLException {
        // 创建QueryRunner，需要提供数据库连接池对象
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        // 给出sql模板
        String sql = "select * from t_stu where sid=?";
        // 给出参数
        Object[] params = {1001};
// 执行query()方法，需要给出结果集处理器，即ResultSetHandler的实现类对象
        // 我们给的是BeanHandler，它实现了ResultSetHandler
        // 它需要一个类型，然后它会把rs中的数据封装到指定类型的javabean对象中，然后返回javabean
        Stu stu = qr.query(sql, new BeanHandler<Stu>(Stu.class), params);
        System.out.println(stu);
    }
    
    /**
     * BeanListHandler的应用，它是多行处理器
     * 每行对象一个Stu对象！
     * @throws Exception
     */
    @Test
    public void fun3() throws Exception {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "select * from t_stu";
        List<Stu> stuList = qr.query(sql, new BeanListHandler<Stu>(Stu.class));
        
        System.out.println(stuList);
    }
    
    /**
     * MapHandler的应用，它是单行处理器，把一行转换成一个Map对象
     * @throws SQLException 
     */
    @Test
    public void fun4() throws SQLException  {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "select * from t_stu where sid=?";
        Object[] params = {1001};
        Map map = qr.query(sql, new MapHandler(), params);
        
        System.out.println(map);
    }
    
    /**
     * MapListHandler，它是多行处理器，把每行都转换成一个Map，即List<Map>
     * @throws SQLException
     */
    @Test
    public void fun5() throws SQLException  {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "select * from t_stu";
        List<Map<String,Object>> mapList = qr.query(sql, new MapListHandler());
        
        System.out.println(mapList);
    }
    
    /**
     * ScalarHandler，它是单行单列时使用，最为合适！
     * @throws SQLException
     */
    @Test
    public void fun6() throws SQLException {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "select count(*) from t_stu";
        /*
         * Integer、Long、BigInteger
         */
        Number cnt = (Number)qr.query(sql, new ScalarHandler());
        
        long c = cnt.longValue();
        System.out.println(c);
    }
}