Flutter旧项目编译报错：AppBarTheme无textTheme及accentColor参数问题

编译旧Flutter项目时出现以下报错：

Running Gradle task 'assembleDebug'...
../../../.pub-cache/hosted/pub.dev/flutter_neumorphic-3.2.0/lib/src/widget/app_bar.dart:183:29: Error: The getter 'textTheme' isn't defined for the class 'AppBarTheme'.
 - 'AppBarTheme' is from 'package:flutter/src/material/app_bar_theme.dart' ('../../../MycodingLibs/flutter/packages/flutter/lib/src/material/app_bar_theme.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'textTheme'.
        style: (appBarTheme.textTheme?.headline5 ??
                            ^^^^^^^^^
../../../.pub-cache/hosted/pub.dev/flutter_neumorphic-3.2.0/lib/src/widget/app.dart:89:7: Error: No named parameter with the name 'accentColor'.
      accentColor: theme.variantColor,
      ^^^^^^^^^^^
../../../MycodingLibs/flutter/packages/flutter/lib/src/material/theme_data.dart:290:11: Context: Found this candidate, but the arguments don't match.
  factory ThemeData({
          ^
Target kernel_snapshot failed: Exception


FAILURE: Build failed with an exception.

* Where:
Script '/home/corecreater/MycodingLibs/flutter/packages/flutter_tools/gradle/flutter.gradle' line: 1201

* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command '/home/corecreater/MycodingLibs/flutter/bin/flutter'' finished with non-zero exit value 1

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 17s
Exception: Gradle task assembleDebug failed with exit code 1

已尝试更新pubspec.yaml中所有依赖包，Android Studio未检测到代码错误，推测是Flutter版本兼容性问题。

• Flutter新版本中移除了AppBarTheme.textTheme属性，改用titleTextStyle和toolbarTextStyle分别控制标题和工具栏文本样式
• accentColor是旧版Flutter ThemeData的参数，新版本已被ColorScheme.secondary替代

方案1：降级Flutter至兼容版本 #

flutter_neumorphic 3.2.0是较旧的版本，仅支持Flutter 2.x系列。执行以下命令降级：

flutter downgrade 2.10.5

降级完成后重新获取依赖：

flutter pub get

方案2：升级flutter_neumorphic到兼容新版本的版本 #

更新pubspec.yaml中的依赖版本为最新兼容版：

flutter_neumorphic: ^3.3.0 # 可根据实际兼容情况选择更高版本

然后执行：

flutter pub get

方案3：手动修改依赖包源码（不推荐） #

如果无法升级或降级，可临时修改flutter_neumorphic的源码：

1. 找到报错文件../../../.pub-cache/hosted/pub.dev/flutter_neumorphic-3.2.0/lib/src/widget/app_bar.dart，将appBarTheme.textTheme?.headline5替换为appBarTheme.titleTextStyle
2. 找到../../../.pub-cache/hosted/pub.dev/flutter_neumorphic-3.2.0/lib/src/widget/app.dart，将accentColor: theme.variantColor替换为colorScheme: ColorScheme.fromSwatch().copyWith(secondary: theme.variantColor)

注意：手动修改源码会在下次flutter pub get时被覆盖，仅作为临时解决办法。

内容的提问来源于stack exchange，提问作者rocerBob