Flutter中AppBarTheme的textTheme弃用问题及替代方案求助

问题场景 #

在Flutter项目中定义主题时，AppBarTheme的textTheme属性被标记为弃用，编译器提示需使用toolbarTextStyle和titleTextStyle替代。相关代码及报错信息如下：

原代码

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

class MyTheme {
  static ThemeData lightTheme(BuildContext context) => ThemeData(
      primarySwatch: Colors.deepPurple,
      fontFamily: GoogleFonts.lato().fontFamily,
      appBarTheme: const AppBarTheme(
        color: Colors.white,
        elevation: 0.0,
        iconTheme: IconThemeData(color: Colors.black),
        // textTheme is deprecated
        textTheme: Theme.of(context).textTheme,
      )
      );

  static ThemeData darkTheme(BuildContext context) => ThemeData(
    brightness: Brightness.dark,
  );
}

错误信息

'textTheme' is deprecated and shouldn't be used. This property is no longer used, please use toolbarTextStyle and titleTextStyle instead.

"textTheme: Theme.of(context).textTheme,"

无效尝试

// titleTextStyle: TextStyle((context).textTheme),

正确解决方案 #

Flutter将原textTheme拆分为两个独立属性，分别对应AppBar上不同文本的样式：

• toolbarTextStyle：控制AppBar工具栏区域的文本样式（如返回按钮旁的辅助文字）
• titleTextStyle：控制AppBar的主标题文本样式

同时注意：原代码中AppBarTheme使用了const修饰，但Theme.of(context)是非常量表达式，因此必须去掉const关键字，否则会触发编译错误。

修改后的完整代码如下：

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

class MyTheme {
  static ThemeData lightTheme(BuildContext context) => ThemeData(
      primarySwatch: Colors.deepPurple,
      fontFamily: GoogleFonts.lato().fontFamily,
      appBarTheme: AppBarTheme(
        color: Colors.white,
        elevation: 0.0,
        iconTheme: const IconThemeData(color: Colors.black),
        // 替换弃用的textTheme
        toolbarTextStyle: Theme.of(context).textTheme.bodyMedium,
        titleTextStyle: Theme.of(context).textTheme.headlineSmall,
      )
      );

  static ThemeData darkTheme(BuildContext context) => ThemeData(
    brightness: Brightness.dark,
  );
}

补充说明 #

如果需要自定义文本样式，可以通过copyWith方法修改属性，例如：

titleTextStyle: Theme.of(context).textTheme.headlineSmall?.copyWith(
  color: Colors.deepPurple,
  fontWeight: FontWeight.bold,
),

内容的提问来源于stack exchange，提问作者Debug