Apache下的Commons项目下的DBUtils中的QueryRunner使用的例子

╰半橙微兮° 2022-07-21 12:22 60阅读 0赞

这几天使用了apache下的commons项目下的子项目dbutils，十分的小巧灵活，只用几个小例子。就可以直接上手使用了。。

不多说了直接上代码了。。

@Test
    	public void queryRunnerTest() throws SQLException
    	{
    
    		Connection connection = DBManager.getConnection();
    
    		QueryRunner queryRunner = new QueryRunner();
    
    		System.out.println("使用Map处理单行记录！=======================================");
    
    		Map<String, Object> map = queryRunner.query(connection, "select * from qt_user where id = 2", new MapHandler(),
    				(Object[]) null);
    
    		for (Iterator<Entry<String, Object>> i = map.entrySet().iterator(); i.hasNext();)
    		{
    			Entry<String, Object> e = i.next();
    			System.out.println(e.getKey() + "=" + e.getValue());
    		}
    
    		System.out.println("处理多行记录!===================================================");
    
    		List<Map<String, Object>> list = queryRunner.query(connection, "select * from qt_user", new MapListHandler(),
    				(Object[]) null);
    
    		for (Map<String, Object> temp : list)
    		{
    			for (Iterator<Entry<String, Object>> iter = temp.entrySet().iterator(); iter.hasNext();)
    			{
    				Entry<String, Object> entry = iter.next();
    
    				System.out.println(entry.getKey() + ", " + entry.getValue());
    			}
    
    			System.out.println("一行记录解析完成************************************************************");
    		}
    
    		System.out.println("使用Bean处理单行记录！");
    
    		User user = queryRunner.query(connection, "select * from qt_user where id=2",
    				new BeanHandler<User>(User.class));
    		System.out.println("username=" + user.getUsername());
    		System.out.println("email=" + user.getEmail());
    
    		System.out.println("使用Array处理单行记录！");
    
    		Object[] array = queryRunner.query(connection, "select * from qt_user where id=2", new ArrayHandler());
    
    		for (int i = 0; i < array.length; i++)
    		{
    			System.out.println(array[i]);
    		}
    
    		System.out.println("使用Array处理多行记录！");
    
    		List<Object[]> arraylist = queryRunner.query(connection, "select * from qt_user ", new ArrayListHandler());
    
    		for (Iterator<Object[]> itr = arraylist.iterator(); itr.hasNext();)
    		{
    			Object[] a = itr.next();
    			System.out.println("--------------");
    			for (int i = 0; i < a.length; i++)
    			{
    				System.out.println(a[i]);
    
    			}
    		}
    
    		System.out.println("使用ColumnListHandler处理单行记录，返回其中指定的一列！");
    
    		List<Object> colList = queryRunner.query(connection, "select * from qt_user where id=3",
    				new ColumnListHandler("username"));
    		for (Iterator<Object> itr = colList.iterator(); itr.hasNext();)
    		{
    			System.out.println(itr.next());
    		}
    
    		System.out.println("使用ScalarHandler处理单行记录，只返回结果集第一行中的指定字段，如未指定字段，则返回第一个字段！");
    
    		Object scalar1 = queryRunner.query(connection, "select * from qt_user", new ScalarHandler("username"));
    		System.out.println(scalar1);
    		Object scalar2 = queryRunner.query(connection, "select *  from qt_user", new ScalarHandler("addtime"));
    		System.out.println(scalar2);
    
    		// 使用自定义的行处理器 // Map中的KEY可按输入顺序输出
    		System.out.println("使用Map处理单行记录(使用自定义行处理器)！");
    
    		Map<String, Object> linkedmap = queryRunner.query(connection, "select * from qt_user where id=2",
    				new MapHandler(new BasicRowProcessor()), (Object[]) null);
    
    		for (Iterator<Entry<String, Object>> i = linkedmap.entrySet().iterator(); i.hasNext();)
    		{
    			Entry<String, Object> e = i.next();
    			System.out.println(e.getKey() + "=" + e.getValue());
    		}
    
    		// 使用自定义的行处理器 // Map中的KEY可按输入顺序输出
    		System.out.println("处理多行记录(使用自定义行处理器)！");
    
    		List<Map<String, Object>> listLinedMap = queryRunner.query(connection, "select *from qt_user ",
    				new MapListHandler(new BasicRowProcessorEx()), (Object[]) null);
    
    		for (Iterator<Map<String, Object>> li = listLinedMap.iterator(); li.hasNext();)
    		{
    			System.out.println("--------------");
    			Map<String, Object> m = li.next();
    			for (Iterator<Entry<String, Object>> mi = m.entrySet().iterator(); mi.hasNext();)
    			{
    				Entry<String, Object> e = mi.next();
    				System.out.println(e.getKey() + "=" + e.getValue());
    			}
    		}
    	}