这个代码中关键的是最外层的Container，大家知道通过mainAxisAlignment: MainAxisAlignment.spaceBetween设置成左右，但是发现不起作用

原因就是Row不知道外层空间的宽度，没法计算要撑开多宽，所以加上Container并指定一个宽度即可。

Container(
	width:  MediaQuery.of(context).size.width,
	child: Row(
		mainAxisAlignment: MainAxisAlignment.spaceBetween,
		children: [
		  Padding(
			padding: EdgeInsets.only(top:0,left: 0,right: 0,bottom: 0),
			child:Row(
			  children: [
				Text(
				  "111111",
				  textAlign:TextAlign.left,
				  style: TextStyle(
					  color: Color(0xffEB5405) ,
					  fontSize: 16,
					  fontWeight: FontWeight.w500
				  ),
				),
				Text(
				  "2222222",
				  textAlign:TextAlign.left,
				  style: TextStyle(
					color: Color(0xff999999) ,
					fontSize: 12,
				  ),
				),
			  ],
			),
		  ),

		  Padding(
			padding: EdgeInsets.only(top:0,left: 0,right: 0,bottom: 0),
			child:Row(
			  mainAxisAlignment: MainAxisAlignment.center,
			  crossAxisAlignment: CrossAxisAlignment.center,
			  children: [
				IconButton(
				  icon: new Icon(Icons.remove_circle_outline_rounded),
				  color: Color(0xff999999),
				  onPressed: _minusCountAction,
				  iconSize: 20,
				),
				Text(
				  _count.toString(),
				  textAlign:TextAlign.center,
				  style: TextStyle(
					color: Color(0xff222222) ,
					fontSize: 18,
				  ),
				),
				IconButton(
				  icon: new Icon(Icons.add_circle_outline_rounded),
				  color: Color(0xff999999),
				  onPressed: _addCountAction,
				  iconSize: 20,
				),
			  ],
			),
		  ),
		]
	),
),