如何在控制台中使用flutter热重载？

Question

我想使用 flutter 开发 Android 应用程序，而不使用 Android Studio 或其他 IDE。我目前正在基于 arch 的 Linux 发行版上安装所有内容。除了热重载功能之外，一切对我来说都运行良好。当我这样做flutter run（甚至flutter run --hot）时，命令执行会卡在以下位置：

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$ flutter run --hot                                                                                                                                     \xee\x82\xb2 \xe2\x9c\x94 \xee\x82\xb2 926 \xee\x82\xb2 10:53:42\nUsing hardware rendering with device AOSP on IA Emulator. If you get graphics artifacts, consider enabling software rendering with "--enable-software-rendering".\nLaunching lib/main.dart on AOSP on IA Emulator in debug mode...\nRunning Gradle task \'assembleDebug\'...                             16.0s\n\xe2\x9c\x93 Built build/app/outputs/apk/debug/app-debug.apk.\nInstalling build/app/outputs/apk/app.apk...                         2.1s\nD/FlutterActivity( 5356): Using the launch theme as normal theme.\nD/FlutterActivityAndFragmentDelegate( 5356): Setting up FlutterEngine.\nD/FlutterActivityAndFragmentDelegate( 5356): No preferred FlutterEngine was provided. Creating a new FlutterEngine for this FlutterFragment.\nD/FlutterActivityAndFragmentDelegate( 5356): Attaching FlutterEngine to the Activity that owns this Fragment.\nD/FlutterView( 5356): Attaching to a FlutterEngine: io.flutter.embedding.engine.FlutterEngine@a4c3a46\nD/FlutterActivityAndFragmentDelegate( 5356): Executing Dart entrypoint: main, and sending initial route: /\nSyncing files to device AOSP on IA Emulator...\nI/Choreographer( 5356): Skipped 39 frames!  The application may be doing too much work on its main thread.\n\nD/EGL_emulation( 5356): eglMakeCurrent: 0xee21eda0: ver 2 0 (tinfo 0xebee8750)\n\nI/OpenGLRenderer( 5356): Davey! duration=855ms; Flags=1, IntendedVsync=1732977740059, Vsync=1733627740033, OldestInputEvent=9223372036854775807, NewestInputEvent=0, HandleInputStart=1733631371135, AnimationStart=1733631552307, PerformTraversalsStart=1733631557297, DrawStart=1733706388536, SyncQueued=1733709834031, SyncStart=1733711094512, IssueDrawCommandsStart=1733711517055, SwapBuffers=1733737182985, FrameCompleted=1733834775355, DequeueBufferDuration=28144000, QueueBufferDuration=9171000,\n\nD/EGL_emulation( 5356): eglMakeCurrent: 0xec205360: ver 2 0 (tinfo 0xec2033b0)\n\nD/eglCodecCommon( 5356): setVertexArrayObject: set vao to 0 (0) 1 0\n

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我所说的卡住是指该程序只是输出日志消息并忽略我的所有输入。我已经尝试过按r或之类的东西R，但它只会导致

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D/eglCodecCommon( 5356): setVertexArrayObject: set vao to 0 (0) 1 0\nrR\n

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并且模拟设备没有反应。

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如果您有兴趣，这里有一些输出：

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flutter doctor结果是：

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[\xe2\x9c\x93] Flutter (Channel stable, v1.12.13+hotfix.8, on Linux, locale en_US.UTF-8)\n    \xe2\x80\xa2 Flutter version 1.12.13+hotfix.8 at /opt/flutter\n    \xe2\x80\xa2 Framework revision 0b8abb4724 (4 weeks ago), 2020-02-11 11:44:36 -0800\n    \xe2\x80\xa2 Engine revision e1e6ced81d\n    \xe2\x80\xa2 Dart version 2.7.0\n\n[\xe2\x9c\x93] Android toolchain - develop for Android devices (Android SDK version 28.0.3)\n    \xe2\x80\xa2 Android SDK at /opt/android-sdk\n    \xe2\x80\xa2 Android NDK location not configured (optional; useful for native profiling support)\n    \xe2\x80\xa2 Platform android-28, build-tools 28.0.3\n    \xe2\x80\xa2 ANDROID_HOME = /opt/android-sdk\n    \xe2\x80\xa2 Java binary at: /usr/bin/java\n    \xe2\x80\xa2 Java version OpenJDK Runtime Environment (build 1.8.0_242-b08)\n    \xe2\x80\xa2 All Android licenses accepted.\n\n[!] Android Studio (not installed)\n    \xe2\x80\xa2 Android Studio not found; download from https://developer.android.com/studio/index.html\n      (or visit https://flutter.dev/setup/#android-setup for detailed instructions).\n\n[\xe2\x9c\x93] Connected device (1 available)\n    \xe2\x80\xa2 AOSP on IA Emulator \xe2\x80\xa2 emulator-5554 \xe2\x80\xa2 android-x86 \xe2\x80\xa2 Android 9 (API 28) (emulator)\n

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由于已请求，这里是输出的最后一部分flutter run -v：

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[  +23 ms] Android Debug Bridge version 1.0.41\n           Version 29.0.6-6198805\n           Installed as /opt/android-sdk/platform-tools/adb\n[   +1 ms] executing: /opt/android-sdk/platform-tools/adb start-server\n[  +19 ms] Installing build/app/outputs/apk/app.apk...\n[        ] executing: /opt/android-sdk/platform-tools/adb -s emulator-5554 install -t -r /home/fox/tmp/testy/build/app/outputs/apk/app.apk\n[+2544 ms] Performing Streamed Install\n           Success\n[        ] Installing build/app/outputs/apk/app.apk... (completed in 2.5s)\n[   +4 ms] executing: /opt/android-sdk/platform-tools/adb -s emulator-5554 shell echo -n d26fd49fc8a8132a5b3be06672c852791523c0be > /data/local/tmp/sky.com.example.testy.sha1\n[  +92 ms] AOSP on IA Emulator startApp\n[   +4 ms] executing: /opt/android-sdk/platform-tools/adb -s emulator-5554 shell am start -a android.intent.action.RUN -f 0x20000000 --ez enable-background-compilation true --ez enable-dart-profiling\ntrue --ez enable-checked-mode true --ez verify-entry-points true com.example.testy/com.example.testy.MainActivity\n[ +379 ms] Starting: Intent { act=android.intent.action.RUN flg=0x20000000 cmp=com.example.testy/.MainActivity (has extras) }\n[   +1 ms] Waiting for observatory port to be available...\n[+1187 ms] D/FlutterActivity( 5901): Using the launch theme as normal theme.\n[   +5 ms] D/FlutterActivityAndFragmentDelegate( 5901): Setting up FlutterEngine.\n[        ] D/FlutterActivityAndFragmentDelegate( 5901): No preferred FlutterEngine was provided. Creating a new FlutterEngine for this FlutterFragment.\n[+1996 ms] D/FlutterActivityAndFragmentDelegate( 5901): Attaching FlutterEngine to the Activity that owns this Fragment.\n[  +95 ms] D/FlutterView( 5901): Attaching to a FlutterEngine: io.flutter.embedding.engine.FlutterEngine@a4c3a46\n[  +54 ms] D/FlutterActivityAndFragmentDelegate( 5901): Executing Dart entrypoint: main, and sending initial route: /\n[ +140 ms] Observatory URL on device: http://127.0.0.1:34706/KylafuV8tWY=/\n[   +3 ms] executing: /opt/android-sdk/platform-tools/adb -s emulator-5554 forward tcp:0 tcp:34706\n[  +14 ms] 44911\n[        ] Forwarded host port 44911 to device port 34706 for Observatory\n[  +12 ms] Connecting to service protocol: http://127.0.0.1:44911/KylafuV8tWY=/\n[ +698 ms] Successfully connected to service protocol: http://127.0.0.1:44911/KylafuV8tWY=/\n[   +5 ms] Sending to VM service: getVM({})\n[  +20 ms] Result: {type: VM, name: vm, architectureBits: 32, hostCPU: Android virtual processor, operatingSystem: android, targetCPU: ia32, version: 2.7.0 (Fri Dec 6 16:26:51 2019 +0100) on\n"android_ia32", _profilerMode: VM, _nativeZoneMemoryUsage: 0, pid: 5901, st...\n[  +14 ms] Sending to VM service: getIsolate({isolateId: isolates/2827659313742019})\n[  +11 ms] Sending to VM service: _flutter.listViews({})\n[  +76 ms] Result: {type: Isolate, id: isolates/2827659313742019, name: main, number: 2827659313742019, _originNumber: 2827659313742019, startTime: 1584009467451, _heaps: {new: {type: HeapSpace,\nname: new, vmName: Scavenger, collections: 2, avgCollectionPeriodMillis...\n[  +30 ms] Result: {type: FlutterViewList, views: [{type: FlutterView, id: _flutterView/0xebf68710, isolate: {type: @Isolate, fixedId: true, id: isolates/2827659313742019, name:\nmain.dart$main-2827659313742019, number: 2827659313742019}}]}\n[  +25 ms] DevFS: Creating new filesystem on the device (null)\n[   +2 ms] Sending to VM service: _createDevFS({fsName: testy})\n[  +58 ms] Result: {type: FileSystem, name: testy, uri: file:///data/user/0/com.example.testy/code_cache/testyTKZBNK/testy/}\n[        ] DevFS: Created new filesystem on the device (file:///data/user/0/com.example.testy/code_cache/testyTKZBNK/testy/)\n[   +2 ms] Updating assets\n[ +137 ms] Syncing files to device AOSP on IA Emulator...\n[   +3 ms] Scanning asset files\n[   +3 ms] <- reset\n[        ] Compiling dart to kernel with 0 updated files\n[  +12 ms] /opt/flutter/bin/cache/dart-sdk/bin/dart /opt/flutter/bin/cache/artifacts/engine/linux-x64/frontend_server.dart.snapshot --sdk-root\n/opt/flutter/bin/cache/artifacts/engine/common/flutter_patched_sdk/ --incremental --target=flutter -Ddart.developer.causal_async_stacks=true --output-dill /tmp/flutter_tool.RFJESY/app.dill --packages\n/home/fox/tmp/testy/.packages -Ddart.vm.profile=false -Ddart.vm.product=false\n--bytecode-options=source-positions,local-var-info,debugger-stops,instance-field-initializers,keep-unreachable-code,avoid-closure-call-instructions --enable-asserts --track-widget-creation\n--filesystem-scheme org-dartlang-root\n[  +20 ms] <- compile package:testy/main.dart\n[  +69 ms] D/EGL_emulation( 5901): eglMakeCurrent: 0xee21f400: ver 2 0 (tinfo 0xee22aaf0)\n[   +5 ms] D/eglCodecCommon( 5901): setVertexArrayObject: set vao to 0 (0) 1 0\n

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的输出flutter devices -v是

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$ flutter devices -v                                                                                                                                              \xee\x82\xb2 \xe2\x9c\x94 \xee\x82\xb2 936 \xee\x82\xb2 14:29:36\n[  +14 ms] executing: [/opt/flutter/] git -c log.showSignature=false log -n 1 --pretty=format:%H\n[  +40 ms] Exit code 0 from: git -c log.showSignature=false log -n 1 --pretty=format:%H\n[        ] 0b8abb4724aa590dd0f429683339b1e045a1594d\n[        ] executing: [/opt/flutter/] git describe --match v*.*.* --first-parent --long --tags\n[   +9 ms] Exit code 0 from: git describe --match v*.*.* --first-parent --long --tags\n[        ] v1.12.13+hotfix.8-0-g0b8abb472\n[   +8 ms] executing: [/opt/flutter/] git rev-parse --abbrev-ref --symbolic @{u}\n[   +8 ms] Exit code 0 from: git rev-parse --abbrev-ref --symbolic @{u}\n[        ] origin/stable\n[        ] executing: [/opt/flutter/] git ls-remote --get-url origin\n[   +7 ms] Exit code 0 from: git ls-remote --get-url origin\n[        ] https://github.com/flutter/flutter.git\n[  +68 ms] executing: [/opt/flutter/] git rev-parse --abbrev-ref HEAD\n[  +11 ms] Exit code 0 from: git rev-parse --abbrev-ref HEAD\n[        ] stable\n[  +41 ms] Artifact Instance of \'AndroidMavenArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'AndroidGenSnapshotArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'AndroidInternalBuildArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'IOSEngineArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'FlutterWebSdk\' is not required, skipping update.\n[   +5 ms] Artifact Instance of \'WindowsEngineArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'MacOSEngineArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'LinuxEngineArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'LinuxFuchsiaSDKArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'MacOSFuchsiaSDKArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'FlutterRunnerSDKArtifacts\' is not required, skipping update.\n[        ] Artifact Instance of \'FlutterRunnerDebugSymbols\' is not required, skipping update.\n[  +83 ms] executing: /opt/android-sdk/platform-tools/adb devices -l\n[  +18 ms] Exit code 0 from: /opt/android-sdk/platform-tools/adb devices -l\n[        ] List of devices attached\n           emulator-5554          device product:sdk_gphone_x86_arm model:AOSP_on_IA_Emulator device:generic_x86_arm transport_id:4\n[  +36 ms] 1 connected device:\n\n[  +14 ms] /opt/android-sdk/platform-tools/adb -s emulator-5554 shell getprop\n[  +87 ms] ro.hardware = ranchu\n[   +6 ms] AOSP on IA Emulator \xe2\x80\xa2 emulator-5554 \xe2\x80\xa2 android-x86 \xe2\x80\xa2 Android 9 (API 28) (emulator)\n[  +15 ms] "flutter devices" took 320ms.\n

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Answer 1

该命令没有“卡住”。它不会结束，直到您退出应用程序，并且它捕获输入以便能够触发某些操作。

在此状态下，键入以下任意字母以触发特定操作：

Flutter run key commands.
r Hot reload. 
R Hot restart.
h Repeat this help message.
d Detach (terminate "flutter run" but leave application running).
c Clear the screen
q Quit (terminate the application on the device).
s Save a screenshot to flutter.png.
w Dump widget hierarchy to the console.                                                     (debugDumpApp)
t Dump rendering tree to the console.                                                (debugDumpRenderTree)
L Dump layer tree to the console.                                                     (debugDumpLayerTree)
S Dump accessibility tree in traversal order.                                         (debugDumpSemantics)
U Dump accessibility tree in inverse hit test order.                                  (debugDumpSemantics)
i Toggle widget inspector.                                        (WidgetsApp.showWidgetInspectorOverride)
p Toggle the display of construction lines.                                        (debugPaintSizeEnabled)
o Simulate different operating systems.                                            (defaultTargetPlatform)
z Toggle elevation checker.
P Toggle performance overlay.                                          (WidgetsApp.showPerformanceOverlay)
a Toggle timeline events for all widget build methods.                          (debugProfileWidgetBuilds)
An Observatory debugger and profiler on sdk gphone x86 is available at:
http://127.0.0.1:50607/ZMvxTxjmDD0=/

Answer 2

好的，我能够解决这个问题。它似乎与最近的 Linux 内核版本 5.xx 有关，您可以在这里自行阅读：

https://github.com/flutter/flutter/issues/49185

如果您不想阅读：我卸载了该flutter软件包并安装了该flutter-git软件包。然后就成功了。