flutter 监测textInput失去焦点和得到焦点

参考：https://blog.csdn.net/weixin_27013291/article/details/112715846

1.创建FocusNode

//创建FocusNode对象实例
 FocusNode focusNode = FocusNode();

2.初始化函数中添加焦点监听

@override
void initState(){
  super.initState();



  //输入框焦点监测
  _focusNode.addListener((){
    if (!_focusNode.hasFocus) {
      print('失去焦点');

    }else{
      print('得到焦点');


    }
  });
}

3.在TextField中引用FocusNode

new TextField(
//引用FocusNode
  focusNode: focusNode,
),

4.在页面Widget销毁时，释放focusNode

//页面销毁
@override
void dispose() {
super.dispose();
//释放
  focusNode.dispose();
}

一般情况需要点击空白处失去焦点，写在当前页面的最顶处组件

GestureDetector(
      behavior: HitTestBehavior.translucent,
      onTap: () {
// 触摸收起键盘
        FocusScope.of(context).requestFocus(FocusNode());
      },
      child: Container()
)

常用方法

//获取焦点
void getFocusFunction(BuildContext context){
  FocusScope.of(context).requestFocus(focusNode);
}

//失去焦点
void unFocusFunction(){
  focusNode.unfocus();
}

//隐藏键盘而不丢失文本字段焦点：
void hideKeyBoard(){
  SystemChannels.textInput.invokeMethod('TextInput.hide');
}