写一个flutter Android TV项目.可以监听到用户对遥控器按钮'上下左右和确定返回键'.获取当前遥控器对焦点,对遥控器当前所在位置添加样式

A：

要实现这个功能，我们需要用到flutter的focus_node来监听控件的焦点变化，并根据不同的状态进行样式的更新。同时，我们也需要使用flutter的RawKeyEvent来监听遥控器按键事件。

首先，我们需要引入flutter的库：

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

然后，定义一个FocusNode，并在控件上与之关联。这样，在控件获取或失去焦点时，就会触发这个FocusNode的监听事件：

FocusNode _focusNode = FocusNode();

...

Widget build(BuildContext context) {
  return Scaffold(
      body: Focus(
          focusNode: _focusNode,
          child: Container(
              width: 200,
              height: 200,
              decoration: BoxDecoration(
                color: _focusNode.hasFocus ? Colors.red : Colors.blue,
              )
          )
      )
  );
}

在上面的代码中，我们给一个Container控件添加了焦点监听，并且在控件中添加了一个背景颜色。当该控件获取焦点时，背景颜色变为红色，失去焦点时则变为蓝色。

接下来，我们需要使用RawKeyEvent来监听遥控器按键事件。这里我们只监听了上下左右和确定返回键：

RawKeyboardListener(
  focusNode: FocusNode(),
  onKey: (RawKeyEvent event) {
    if (event is RawKeyDownEvent) {
      if (event.logicalKey == LogicalKeyboardKey.arrowUp) {
        // up key is pressed
      } else if (event.logicalKey == LogicalKeyboardKey.arrowDown) {
        // down key is pressed
      } else if (event.logicalKey == LogicalKeyboardKey.arrowLeft) {
        // left key is pressed
      } else if (event.logicalKey == LogicalKeyboardKey.arrowRight) {
        // right key is pressed
      } else if (event.logicalKey == LogicalKeyboardKey.select) {
        // enter key is pressed
      } else if (event.logicalKey == LogicalKeyboardKey.backspace) {
        // back key is pressed
      }
    }
  },
  child: Container()
),

在监听到不同的遥控器按键事件后，我们可以对当前焦点的控件进行样式的更新，例如：

RawKeyboardListener(
  focusNode: FocusNode(),
  onKey: (RawKeyEvent event) {
    if (event is RawKeyDownEvent) {
      if (event.logicalKey == LogicalKeyboardKey.arrowUp) {
        // up key is pressed
        if (_focusNode.hasFocus) {
          setState(() {
            _focusNode.nextFocus();
          });
        }
      } else if (event.logicalKey == LogicalKeyboardKey.arrowDown) {
        // down key is pressed
        if (_focusNode.hasFocus) {
          setState(() {
            _focusNode.previousFocus();
          });
        }
      } else if (event.logicalKey == LogicalKeyboardKey.arrowLeft) {
        // left key is pressed
        if (_focusNode.hasFocus) {
          setState(() {
            _focusNode.requestFocus(FocusNode().canRequestFocus ? FocusNode() : null);
          });
        }
      } else if (event.logicalKey == LogicalKeyboardKey.arrowRight) {
        // right key is pressed
        if (_focusNode.hasFocus) {
          setState(() {
            _focusNode.requestFocus(FocusNode().canRequestFocus ? FocusNode() : null);
          });
        }
      } else if (event.logicalKey == LogicalKeyboardKey.select) {
        // enter key is pressed
        if (_focusNode.hasFocus) {
          setState(() {
            // update the selected widget style
          });
        } 
      } else if (event.logicalKey == LogicalKeyboardKey.backspace) {
        // back key is pressed
        if (_focusNode.hasFocus) {
          setState(() {
            _focusNode.unfocus();
          });
        }
      }
    }
  },
  child: Container()
),

在上面的代码中，我们根据遥控器按键事件的不同，对控件的焦点和样式进行了更新。例如，当焦点控件为当前控件时，按下上下左右键可移动焦点；按下确定键时，更新当前控件样式。

以上就是实现这个功能的简单示例代码，我们可以在实际开发中根据需要进行修改和优化。