flutter channel通道切换与Config

flutter channel 有四个版本，按稳定度递增排序分别是：

• master 最初的版本，功能可能会在后面的版本中被删减
• dev 由master过来的经过全面测试的，比master更稳定完善的版本
• beta 由master分支过来的，比dev版本更稳定的版本
• stable 由beta版本过来的，最终稳定的版本，生产环境建议使用此版本

有时候我们切换到某一个版本是为了使用stable暂不支持的功能，要了解某个功能在哪个版本受支持时，需要用到config命令,举例：我需要用flutter 开发windows客户端程序，这个时候我需要知道有哪些flutter版本目前是支持该功能的，所以我执行：

flutter config

得到如下数据：

Configure Flutter settings.

To remove a setting, configure it to an empty string.

The Flutter tool anonymously reports feature usage statistics and basic crash reports to help improve Flutter tools over time. See Google's privacy policy: https://www.google.com/intl/en/policies/privacy/

Global options:
-h, --help                  Print this usage information.
-v, --verbose               Noisy logging, including all shell commands executed.
                            If used with --help, shows hidden options.
-d, --device-id             Target device id or name (prefixes allowed).
    --version               Reports the version of this tool.
    --suppress-analytics    Suppress analytics reporting when this command runs.

Usage: flutter config [arguments]
-h, --help                                      Print this usage information.
    --[no-]analytics                            Enable or disable reporting anonymously tool usage statistics and crash reports.
    --clear-ios-signing-cert                    Clear the saved development certificate choice used to sign apps for iOS device deployment.
    --android-sdk                               The Android SDK directory.
    --android-studio-dir                        The Android Studio install directory.
    --build-dir=<out/>                          The relative path to override a projects build directory
    --[no-]enable-web                           Enable or disable Flutter for web. This setting will take effect on the master, dev, and beta channels.
    --[no-]enable-linux-desktop                 Enable or disable Flutter for desktop on Linux. This setting will take effect on the master and dev channels.
    --[no-]enable-macos-desktop                 Enable or disable Flutter for desktop on macOS. This setting will take effect on the master and dev channels.
    --[no-]enable-windows-desktop               Enable or disable Flutter for desktop on Windows. This setting will take effect on the master channel.
    --[no-]single-widget-reload-optimization    Enable or disable Hot reload optimization for changes to class body of a single widget. This setting will take effect on the master, dev, beta, and stable
                                                channels.
    --[no-]enable-android                       Enable or disable Flutter for Android. This setting will take effect on the master, dev, beta, and stable channels.
    --[no-]enable-ios                           Enable or disable Flutter for iOS. This setting will take effect on the master, dev, beta, and stable channels.
    --[no-]enable-fuchsia                       Enable or disable Flutter for Fuchsia. This setting will take effect on the master channel.
    --clear-features                            Remove all configured features and restore them to the default values.

Run "flutter help" to see global options.

Settings:
  enable-web: true
  enable-windows-desktop: true (Unavailable)

Analytics reporting is currently enabled.

使用该方法可以看到上面的enable-windows-desktop后面的描述信息，指明了启用该功能仅在master版本上产生作用。
所以我仅需执行下面的命令执行切换版本动作：

flutter channel master //flutter channel 可以看到所有的版本

注意：如果一直没有响应，可以尝试到flutter安装目录执行：git clean -xffd命令后再做切换。
切换成功后将会提示：

Switching to flutter channel 'master'...
git: Branch 'master' set up to track remote branch 'master' from 'origin'.
git: Switched to a new branch 'master'
Successfully switched to flutter channel 'master'.
To ensure that you're on the latest build from this channel, run 'flutter upgrade'

根据最后一行的信息我们知道，需要更新版本，所以跟着操作就可以了：

flutter upgrade

成功后得到下面的信息表示成功：

Checking Dart SDK version...
Downloading Dart SDK from Flutter engine 3a73d073c8bedb678d82ee78daf05037b3a7a85e...
Building flutter tool...
Running pub upgrade...
Flutter is already up to date on channel master
Flutter 1.22.0-10.0.pre.380 • channel master • https://github.com/flutter/flutter.git
Framework • revision ec40df9576 (22 hours ago) • 2020-09-25 21:27:22 -0700
Engine • revision 3a73d073c8
Tools • Dart 2.11.0 (build 2.11.0-161.0.dev)

最后，运行devices命令查看已经连接的客户端：

flutter devices

出现下面的结果表示一切准备就绪，可以开始编码了：

4 connected devices:

MX5 (mobile)      • 85GBBM82258V • android-arm64  • Android 5.1 (API 22)
Windows (desktop) • windows      • windows-x64    • Microsoft Windows [Version 10.0.18362.1016]
Web Server (web)  • web-server   • web-javascript • Flutter Tools
Chrome (web)      • chrome       • web-javascript • Google Chrome 79.0.3945.88

提示：

windows开发需要在visual studio里面下载安装c++桌面开发程序

• Visual Studio 2019 (not to be confused with Visual Studio Code) with the “Desktop development with C++” workload installed, including all of its default components