Gradle 'xxx' project refresh failed Error:Connection timed out: connect

今天将电脑中的Android Studio 3.0 Canary 1升级Android Studio 3.0 Canary 2后，出现“Connection timed out: connect”错误，这里记录下解决过程，给同样入坑的路人

更新完Android Studio 3.0 Canary 2后错误是这样的：

Error:A problem occurred configuring root project 'xxx'.> Could not resolve all files for configuration ':classpath'.   > Could not download builder.jar (com.android.tools.build:builder:3.0.0-alpha1)      > Could not get resource 'https://maven.google.com/com/android/tools/build/builder/3.0.0-alpha1/builder-3.0.0-alpha1.jar'.         > Could not GET 'https://maven.google.com/com/android/tools/build/builder/3.0.0-alpha1/builder-3.0.0-alpha1.jar'.            > Connect to maven.google.com:443 [maven.google.com/216.58.200.46] failed: Connection timed out: connect

一开始我以为是被墙了，挂上VPN点击“Invalidate Caches / Restart”清除缓存重启，可是问题还在，于是我又开始逛Google和Stackoverflow，找到了一个方法：

Mac/Linux：

./gradlew tasks --offline

Windows：

gradlew tasks --offline

可是结果并不如我想的那么乐观，电脑本地没有新版本相关文件的缓存：

D:\AndroidStudioProjects\xxx>gradlew tasks --offlineFAILURE: Build failed with an exception.* What went wrong:A problem occurred configuring root project 'xxx'.> Could not resolve all files for configuration ':classpath'.   > Could not resolve all dependencies for configuration ':classpath'.      > Could not resolve org.jetbrains.kotlin:kotlin-gradle-plugin:1.1.2-4.        Required by:            project :         > No cached version of org.jetbrains.kotlin:kotlin-gradle-plugin:1.1.2-4 available for offline mode.         > No cached version of org.jetbrains.kotlin:kotlin-gradle-plugin:1.1.2-4 available for offline mode.      > Could not resolve com.android.tools.external.com-intellij:uast:171.4249.33.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.lint:lint:26.0.0-alpha1 > com.android.tools.lint:lint-checks:26.0.0-alpha1 > com.android.tools.lint:lint-api:26.0.0-alpha1         > No cached version of com.android.tools.external.com-intellij:uast:171.4249.33 available for offline mode.         > No cached version of com.android.tools.external.com-intellij:uast:171.4249.33 available for offline mode.      > Could not resolve org.ow2.asm:asm-util:5.0.4.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1         > No cached version of org.ow2.asm:asm-util:5.0.4 available for offline mode.         > No cached version of org.ow2.asm:asm-util:5.0.4 available for offline mode.      > Could not resolve net.sf.proguard:proguard-gradle:5.3.3.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1         > No cached version of net.sf.proguard:proguard-gradle:5.3.3 available for offline mode.         > No cached version of net.sf.proguard:proguard-gradle:5.3.3 available for offline mode.      > Could not resolve org.jacoco:org.jacoco.core:0.7.4.201502262128.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1         > No cached version of org.jacoco:org.jacoco.core:0.7.4.201502262128 available for offline mode.         > No cached version of org.jacoco:org.jacoco.core:0.7.4.201502262128 available for offline mode.      > Could not resolve org.jacoco:org.jacoco.report:0.7.4.201502262128.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1         > No cached version of org.jacoco:org.jacoco.report:0.7.4.201502262128 available for offline mode.         > No cached version of org.jacoco:org.jacoco.report:0.7.4.201502262128 available for offline mode.      > Could not resolve org.bouncycastle:bcpkix-jdk15on:1.56.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools:sdk-common:26.0.0-alpha1         > No cached version of org.bouncycastle:bcpkix-jdk15on:1.56 available for offline mode.         > No cached version of org.bouncycastle:bcpkix-jdk15on:1.56 available for offline mode.      > Could not resolve org.bouncycastle:bcprov-jdk15on:1.56.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools:sdk-common:26.0.0-alpha1         > No cached version of org.bouncycastle:bcprov-jdk15on:1.56 available for offline mode.         > No cached version of org.bouncycastle:bcprov-jdk15on:1.56 available for offline mode.      > Could not resolve org.jetbrains.kotlin:kotlin-runtime:1.0.5.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.lint:lint:26.0.0-alpha1         > No cached version of org.jetbrains.kotlin:kotlin-runtime:1.0.5 available for offline mode.         > No cached version of org.jetbrains.kotlin:kotlin-runtime:1.0.5 available for offline mode.      > Could not resolve org.jetbrains.kotlin:kotlin-stdlib:1.0.5.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.lint:lint:26.0.0-alpha1         > No cached version of org.jetbrains.kotlin:kotlin-stdlib:1.0.5 available for offline mode.         > No cached version of org.jetbrains.kotlin:kotlin-stdlib:1.0.5 available for offline mode.      > Could not resolve com.google.guava:guava:19.0.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:gradle-api:3.0.0-alpha1            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.databinding:compilerCommon:3.0.0-alpha1            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools:common:26.0.0-alpha1            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools.analytics-library:shared:26.0.0-alpha1            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools.analytics-library:tracker:26.0.0-alpha1         > No cached version of com.google.guava:guava:19.0 available for offline mode.         > No cached version of com.google.guava:guava:19.0 available for offline mode.      > Could not resolve com.google.code.gson:gson:2.3.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools:sdklib:26.0.0-alpha1            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools.build:manifest-merger:26.0.0-alpha1            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools.analytics-library:shared:26.0.0-alpha1         > No cached version of com.google.code.gson:gson:2.3 available for offline mode.         > No cached version of com.google.code.gson:gson:2.3 available for offline mode.      > Could not resolve org.apache.httpcomponents:httpclient:4.2.6.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools:sdklib:26.0.0-alpha1         > No cached version of org.apache.httpcomponents:httpclient:4.2.6 available for offline mode.         > No cached version of org.apache.httpcomponents:httpclient:4.2.6 available for offline mode.      > Could not resolve com.google.guava:guava:19.0.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.build:builder:3.0.0-alpha1 > com.android.tools:sdklib:26.0.0-alpha1 > com.android.tools:repository:26.0.0-alpha1 > com.google.jimfs:jimfs:1.1         > No cached version of com.google.guava:guava:19.0 available for offline mode.         > No cached version of com.google.guava:guava:19.0 available for offline mode.      > Could not resolve com.google.guava:guava:19.0.        Required by:            project : > com.android.tools.build:gradle:3.0.0-alpha1 > com.android.tools.build:gradle-core:3.0.0-alpha1 > com.android.tools.lint:lint:26.0.0-alpha1 > com.android.tools.lint:lint-checks:26.0.0-alpha1 > com.android.tools.lint:lint-api:26.0.0-alpha1 > com.android.tools.external.lombok:lombok-ast:0.2.3         > No cached version of com.google.guava:guava:19.0 available for offline mode.         > No cached version of com.google.guava:guava:19.0 available for offline mode.   > Could not download builder.jar (com.android.tools.build:builder:3.0.0-alpha1): No cached version available for offline mode* Try:Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.BUILD FAILED in 1s

最后我尝试着去掉“–offline”，在Terminal中再次运行

gradlew tasks

等了一会总算下载完成并且重新Build（期间VPN继续挂着）

D:\AndroidStudioProjects\xxx>gradlew tasksDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-gradle-plugin/1.1.2-4/kotlin-gradle-plugin-1.1.2-4.pomDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-gradle-plugin-api/1.1.2-4/kotlin-gradle-plugin-api-1.1.2-4.pomDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-stdlib/1.1.2-4/kotlin-stdlib-1.1.2-4.pomDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-project/1.1.2-4/kotlin-project-1.1.2-4.pomDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-android-extensions/1.1.2-4/kotlin-android-extensions-1.1.2-4.pomDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-compiler-embeddable/1.1.2-4/kotlin-compiler-embeddable-1.1.2-4.pomDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-compiler-runner/1.1.2-4/kotlin-compiler-runner-1.1.2-4.pomDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-annotation-processing/1.1.2-4/kotlin-annotation-processing-1.1.2-4.pomDownload https://maven.google.com/com/android/tools/external/com-intellij/uast/171.4249.33/uast-171.4249.33.pomDownload https://maven.google.com/com/android/tools/build/transform-api/2.0.0-deprecated-use-gradle-api/transform-api-2.0.0-deprecated-use-gradle-api.pomDownload https://jcenter.bintray.com/org/ow2/asm/asm-util/5.0.4/asm-util-5.0.4.pomDownload https://jcenter.bintray.com/net/sf/proguard/proguard-gradle/5.3.3/proguard-gradle-5.3.3.pomDownload https://jcenter.bintray.com/net/sf/proguard/proguard-parent/5.3.3/proguard-parent-5.3.3.pomDownload https://jcenter.bintray.com/org/jacoco/org.jacoco.report/0.7.4.201502262128/org.jacoco.report-0.7.4.201502262128.pomDownload https://jcenter.bintray.com/org/bouncycastle/bcpkix-jdk15on/1.56/bcpkix-jdk15on-1.56.pomDownload https://jcenter.bintray.com/org/bouncycastle/bcprov-jdk15on/1.56/bcprov-jdk15on-1.56.pomDownload https://jcenter.bintray.com/org/jetbrains/trove4j/trove4j/20160824/trove4j-20160824.pomDownload https://jcenter.bintray.com/net/sf/proguard/proguard-base/5.3.3/proguard-base-5.3.3.pomDownload https://jcenter.bintray.com/com/google/code/gson/gson/2.3/gson-2.3.pomDownload https://jcenter.bintray.com/org/apache/httpcomponents/httpclient/4.2.6/httpclient-4.2.6.pomDownload https://jcenter.bintray.com/org/apache/httpcomponents/httpcomponents-client/4.2.6/httpcomponents-client-4.2.6.pomDownload https://jcenter.bintray.com/org/apache/httpcomponents/httpcore/4.2.5/httpcore-4.2.5.pomDownload https://jcenter.bintray.com/org/apache/httpcomponents/httpcomponents-core/4.2.5/httpcomponents-core-4.2.5.pomDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-android-extensions/1.1.2-4/kotlin-android-extensions-1.1.2-4.jarDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-gradle-plugin/1.1.2-4/kotlin-gradle-plugin-1.1.2-4.jarDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-gradle-plugin-api/1.1.2-4/kotlin-gradle-plugin-api-1.1.2-4.jarDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-stdlib/1.1.2-4/kotlin-stdlib-1.1.2-4.jarDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-compiler-runner/1.1.2-4/kotlin-compiler-runner-1.1.2-4.jarDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-annotation-processing/1.1.2-4/kotlin-annotation-processing-1.1.2-4.jarDownload https://maven.google.com/com/android/tools/build/builder/3.0.0-alpha1/builder-3.0.0-alpha1.jarDownload https://maven.google.com/com/android/tools/external/com-intellij/uast/171.4249.33/uast-171.4249.33.jarDownload https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-compiler-embeddable/1.1.2-4/kotlin-compiler-embeddable-1.1.2-4.jarDownload https://maven.google.com/com/android/tools/build/transform-api/2.0.0-deprecated-use-gradle-api/transform-api-2.0.0-deprecated-use-gradle-api.jarDownload https://jcenter.bintray.com/org/ow2/asm/asm-util/5.0.4/asm-util-5.0.4.jarDownload https://jcenter.bintray.com/net/sf/proguard/proguard-gradle/5.3.3/proguard-gradle-5.3.3.jarDownload https://jcenter.bintray.com/org/jacoco/org.jacoco.report/0.7.4.201502262128/org.jacoco.report-0.7.4.201502262128.jarDownload https://jcenter.bintray.com/org/bouncycastle/bcpkix-jdk15on/1.56/bcpkix-jdk15on-1.56.jarDownload https://jcenter.bintray.com/org/bouncycastle/bcprov-jdk15on/1.56/bcprov-jdk15on-1.56.jarDownload https://jcenter.bintray.com/org/jetbrains/trove4j/trove4j/20160824/trove4j-20160824.jarDownload https://jcenter.bintray.com/net/sf/proguard/proguard-base/5.3.3/proguard-base-5.3.3.jarDownload https://jcenter.bintray.com/com/google/code/gson/gson/2.3/gson-2.3.jarDownload https://jcenter.bintray.com/org/apache/httpcomponents/httpclient/4.2.6/httpclient-4.2.6.jarDownload https://jcenter.bintray.com/org/apache/httpcomponents/httpcore/4.2.5/httpcore-4.2.5.jarConfiguration 'compile' in project ':app' is deprecated. Use 'implementation' instead.Configuration 'androidTestCompile' in project ':app' is deprecated. Use 'androidTestImplementation' instead.Configuration 'testCompile' in project ':app' is deprecated. Use 'testImplementation' instead.:tasks------------------------------------------------------------All tasks runnable from root project------------------------------------------------------------Android tasks-------------androidDependencies - Displays the Android dependencies of the project.signingReport - Displays the signing info for each variant.sourceSets - Prints out all the source sets defined in this project.Build tasks-----------assemble - Assembles all variants of all applications and secondary packages.assembleAndroidTest - Assembles all the Test applications.assembleDebug - Assembles all Debug builds.assembleRelease - Assembles all Release builds.build - Assembles and tests this project.buildDependents - Assembles and tests this project and all projects that depend on it.buildNeeded - Assembles and tests this project and all projects it depends on.clean - Deletes the build directory.cleanBuildCache - Deletes the build cache directory.compileDebugAndroidTestSourcescompileDebugSourcescompileDebugUnitTestSourcescompileReleaseSourcescompileReleaseUnitTestSourcesmockableAndroidJar - Creates a version of android.jar that's suitable for unit tests.Build Setup tasks-----------------init - Initializes a new Gradle build.wrapper - Generates Gradle wrapper files.Help tasks----------buildEnvironment - Displays all buildscript dependencies declared in root project 'xxx'.components - Displays the components produced by root project 'xxx'. [incubating]dependencies - Displays all dependencies declared in root project 'xxx'.dependencyInsight - Displays the insight into a specific dependency in root project 'xxx'.dependentComponents - Displays the dependent components of components in root project 'xxx'. [incubating]help - Displays a help message.model - Displays the configuration model of root project 'xxx'. [incubating]projects - Displays the sub-projects of root project 'xxx'.properties - Displays the properties of root project 'xxx'.tasks - Displays the tasks runnable from root project 'xxx' (some of the displayed tasks may belong to subprojects).Install tasks-------------installDebug - Installs the Debug build.installDebugAndroidTest - Installs the android (on device) tests for the Debug build.uninstallAll - Uninstall all applications.uninstallDebug - Uninstalls the Debug build.uninstallDebugAndroidTest - Uninstalls the android (on device) tests for the Debug build.uninstallRelease - Uninstalls the Release build.Verification tasks------------------check - Runs all checks.connectedAndroidTest - Installs and runs instrumentation tests for all flavors on connected devices.connectedCheck - Runs all device checks on currently connected devices.connectedDebugAndroidTest - Installs and runs the tests for debug on connected devices.deviceAndroidTest - Installs and runs instrumentation tests using all Device Providers.deviceCheck - Runs all device checks using Device Providers and Test Servers.lint - Runs lint on all variants.lintDebug - Runs lint on the Debug build.lintRelease - Runs lint on the Release build.test - Run unit tests for all variants.testDebugUnitTest - Run unit tests for the debug build.testReleaseUnitTest - Run unit tests for the release build.To see all tasks and more detail, run gradlew tasks --allTo see more detail about a task, run gradlew help --task <task>BUILD SUCCESSFUL in 5m 55s1 actionable task: 1 executed, 0 avoided (0%)D:\AndroidStudioProjects\xxx>

最后Android Studio会弹出个对话框，当前版本用了一个不兼容Gradle插件，问我们是否升级，点“Update”，稍等一会完工！

扯了那么多，最终出场主角不过一条指令:)

gradlew tasks

---

2017-06-06更新：

刚更新Android Studio 3.0 Canary 3，又出现了上面问题，这次使用gradlew tasks再点Try Again还是不行，试了下：

gradlew tasks --all

再点Try Again就可以了，最后会弹出Update对话框，点击Update即可