flutter build apk 是出错：
[ +91 ms] Exception in thread "main" java.net.SocketException: Unexpected end of file from server
[ ] at java.base/sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:936)
[ ] at java.base/sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:759)
[ ] at java.base/sun.net.www.protocol.http.HttpURLConnection.doTunneling0(HttpURLConnection.java:2174)
[ ] at java.base/sun.net.www.protocol.http.HttpURLConnection.doTunneling(HttpURLConnection.java:2136)
[ ] at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
[ ] at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1665)
[ ] 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)
问题错误：
至此终于发现问题所在：gradle-5.6.2-all.zip下载失败
解决方案：
本人修改~/.gradle/gradle.properties 发现里面有代理设置，注释掉正常了。
org.gradle.parallel=true
#Sun Aug 27 10:40:02 CST 2023
#systemProp.http.proxyHost=127.0.0.1
#systemProp.http.proxyPort=7891
#systemProp.https.proxyHost=127.0.0.1
#systemProp.https.proxyPort=7891
~
window下：
手动下载Gradle：比如可以参考https://blog.csdn.net/chrisyuu/article/details/52711025
当然，我最后发现，我这个问题的原因是因为在我的C:/Users//.gradle/gradle.properties（不是项目下的gradle.properities）中有几行多余的代理设置，删掉就好了……如果有人遇到相同的问题也可以查看一下这个文件~
参考链接：https://www.jianshu.com/p/5aa8c2fbd3d1