Flutter示例应用无法在AVD虚拟设备启动的问题求助

问题描述 #

尝试使用代理、VPN，但基础Flutter示例应用仍无法在AVD（Android虚拟设备）上运行！该应用在Chrome中启动运行正常，网络状态良好，能够ping通主机，且flutter doctor检测结果无报错。启动过程中出现如下错误：

Launching lib\main.dart on sdk gphone64 x86 64 in debug mode...
main.dart:1
Exception in thread "main" java.net.ConnectException: Connection timed out: connect
    at java.base/sun.nio.ch.Net.connect0(Native Method)
    at java.base/sun.nio.ch.Net.connect(Net.java:579)
    at java.base/sun.nio.ch.Net.connect(Net.java:568)
    at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:588)
    at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:327)
    at java.base/java.net.Socket.connect(Socket.java:633)
    at java.base/sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:304)
    at java.base/sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:174)
    at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:183)
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:531)
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:636)
    at java.base/sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:266)
    at java.base/sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:380)
    at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:193)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1242)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1128)
    at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:179)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.followRedirect0(HttpURLConnection.java:2902)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.followRedirect(HttpURLConnection.java:2811)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1927)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1589)
    at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:224)
    at org.gradle.wrapper.Download.downloadInternal(Download.java:58)
    at org.gradle.wrapper.Download.download(Download.java:44)
    at org.gradle.wrapper.Install$1.call(Install.java:61)
    at org.gradle.wrapper.Install$1.call(Install.java:48)
    at org.gradle.wrapper.ExclusiveFileAccessManager.access(ExclusiveFileAccessManager.java:65)
    at org.gradle.wrapper.Install.createDist(Install.java:48)
    at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:128)
    at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)
Exception: Gradle task assembleDebug failed with exit code 1

解决方案 #

1. 检查并调整Gradle代理配置 #

• 打开项目内的android/gradle.properties文件，检查是否存在代理配置项。若有，确认代理地址、端口是否正确，或暂时注释掉（添加#前缀）：

  # systemProp.http.proxyHost=your-proxy-host
  # systemProp.http.proxyPort=your-proxy-port
  # systemProp.https.proxyHost=your-proxy-host
  # systemProp.https.proxyPort=your-proxy-port
  

• 同时检查全局Gradle配置文件（Windows路径：C:\Users\<你的用户名>\.gradle\gradle.properties；Linux/macOS路径：~/.gradle/gradle.properties），做同样的代理检查与调整。

2. 配置Flutter代理（或重置代理） #

• 若需要代理，执行以下命令设置Flutter的HTTP/HTTPS代理：

  flutter config --set http-proxy http://your-proxy-host:port
  flutter config --set https-proxy https://your-proxy-host:port
  

• 若无需代理，执行命令重置：

  flutter config --unset http-proxy
  flutter config --unset https-proxy
  

3. 解决AVD网络代理冲突 #

• 打开AVD管理器，编辑目标虚拟设备，点击Show Advanced Settings，找到Proxy选项，设置为No proxy或与系统一致的代理配置。
• 重启AVD后，重新尝试运行项目。

4. 手动下载Gradle Wrapper #

• 从错误日志中确认需要下载的Gradle版本，直接下载对应版本的zip包。
• 将zip包放到路径C:\Users\<你的用户名>\.gradle\wrapper\dists\<gradle版本号>\<随机字符串>下，解压后重新执行flutter run。

5. 清除缓存并重新构建 #

• 执行以下命令清除Flutter和Gradle缓存：

  flutter clean
  cd android
  ./gradlew clean
  ./gradlew build --refresh-dependencies
  

• 返回项目根目录，再次运行flutter run。

内容的提问来源于stack exchange，提问作者Seyed Ahmadreza Dehghanian