问题：Launching lib\main.dart on ELE AL00 in debug mode…
Running Gradle task ‘assembleDebug’…
Exception in thread “main” java.net.ConnectException: Connection timed out: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:666)
at sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:173)
at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:463)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:558)
at sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:264)
at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:367)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:191)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1156)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1050)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:177)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1564)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:263)
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、调整项目空间中的gradle-wrapper.properties文件中的URL，改为你本地最新的gradle版本就好
如：
distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.4-all.zip
2、调整Android包中的build.gradle文件中的kotlin版本号：跟本地kotlin版本同步就行
如：ext.kotlin_version = ‘1.3.50’