Flutter AppCenter构建失败：java.net.URISyntaxException异常求助

问题场景 #

配置Flutter应用的AppCenter构建后，运行构建时失败，报错核心信息为java.net.URISyntaxException: Illegal character in opaque part。本地Android Studio可正常运行该应用。

错误日志 #

FAILURE: Build failed with an exception.

 Where:
Settings file '/Users/runner/work/1/s/android/settings.gradle' line: 11

 What went wrong:
A problem occurred evaluating settings 'android'.
> java.net.URISyntaxException: Illegal character in opaque part at index 2: C:\Users\...\Flutter\sdk\flutter_windows_2.8.1-stable\flutter\packages\flutter_tools\gradle\app_plugin_loader.gradle

BUILD FAILED in 14s
Error: /Users/runner/work/1/s/android/gradlew failed with return code: 1
    at ChildProcess.<anonymous> (/Users/runner/work/_tasks/Gradle_8d8eebd8-2b94-4c97-85af-839254cc6da4/1.128.0/node_modules/vsts-task-lib/toolrunner.js:569:30)
    at emitTwo (events.js:106:13)
    at ChildProcess.emit (events.js:191:7)
    at maybeClose (internal/child_process.js:920:16)
    at Socket.<anonymous> (internal/child_process.js:351:11)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:188:7)
    at Pipe._handle.close [as _onclose] (net.js:509:12)
##[error]Error: /Users/runner/work/1/s/android/gradlew failed with return code: 1

相关代码片段 #

settings.gradle：

include ':app'

def localPropertiesFile = new File(rootProject.projectDir, "local.properties")
def properties = new Properties()

assert localPropertiesFile.exists()
localPropertiesFile.withReader("UTF-8") { reader -> properties.load(reader) }

def flutterSdkPath = properties.getProperty("flutter.sdk")
assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
apply from: "$flutterSdkPath\packages\flutter_tools\gradle\app_plugin_loader.gradle"

local.properties：

sdk.dir=C:\Users\..\AppData\Local\Android\sdk
flutter.sdk=C:\Users\..\Flutter\sdk\flutter_windows_2.8.1-stable\flutter
flutter.buildMode=debug
flutter.versionName=1.0.0
flutter.versionCode=1

原因分析 #

1. 路径分隔符跨平台不兼容：
   local.properties中使用了Windows风格的反斜杠\，但AppCenter构建环境为macOS/Linux（从日志中的/Users/runner可判断），这类系统仅支持正斜杠/作为路径分隔符，反斜杠会被识别为非法字符。
2. Groovy字符串转义问题：
   settings.gradle中拼接路径时用了\，在Groovy语法里反斜杠是转义字符，实际解析后会导致路径格式错误，触发URISyntaxException。
3. 本地与构建环境差异：
   本地Android Studio运行在Windows环境，支持反斜杠路径，因此无问题；但AppCenter的构建 runner 是类Unix系统，路径规则不同导致报错。

解决方案 #

1. 修正路径分隔符 #

将local.properties中的反斜杠\替换为正斜杠/，确保跨平台兼容：

sdk.dir=C:/Users/../AppData/Local/Android/sdk
flutter.sdk=C:/Users/../Flutter/sdk/flutter_windows_2.8.1-stable/flutter
flutter.buildMode=debug
flutter.versionName=1.0.0
flutter.versionCode=1

2. 修复settings.gradle的路径拼接 #

把settings.gradle中的反斜杠\改为正斜杠/：

apply from: "$flutterSdkPath/packages/flutter_tools/gradle/app_plugin_loader.gradle"

3. 优化版本控制（推荐） #

local.properties是本地环境配置文件，不应提交到Git仓库。检查项目的.gitignore是否包含local.properties，AppCenter会自动在构建环境中配置Flutter和Android SDK路径，无需手动指定。

内容的提问来源于stack exchange，提问作者Ramachandra Reddy Avula