flutter

flutter基本学习

Posted by sqq5682 on January 10, 2022

安装 Flutter

git clone -b stable https://github.com/flutter/flutter.git

检测 Flutter 环境

flutter doctor

创建 Flutter 工程

flutter create myapp

列出模拟器

flutter emulators

启动一个Android 模拟器

flutter emulators --launch Nexus_5X_9.0

列出当前开启的模拟器设备

flutter devices
# 显示对应的二个模拟器设备
3 connected devices:
Android SDK built for x86 • emulator-5554 • android-x86 • Android 9 (API 28) (emulator)
iPhone X • 67ADA545-4FC6-458D-AE43-CC6CAF013A6B • ios • iOS 12.1 (simulator)

指定设备设备运行模拟器

flutter run -d emulator-5554

Flutter run key commands.

r Hot reload. 🔥🔥🔥 R Hot restart. h List all available interactive commands. d Detach (terminate “flutter run” but leave application running). c Clear the screen q Quit (terminate the application on the device).

关于Flutter报Cannot run with sound null safety的解决方法 flutter sdk 版本升级到2.0或者更高的版本后，运行之前的代码会报错，比如：

Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:

 - package:flutter_swiper
 - package:flutter_page_indicator
 - package:transformer_page_view

For solutions, see https://dart.dev/go/unsound-null-safety
FAILURE: Build failed with an exception.

上面的问题是，这些包不支持 safety模式。我们可以在运行的时候添加–no-sound-null-safety

flutter run -d emulator-5554 --no-sound-null-safety

flutter 安装问题 (macbook pro m1)

1.获取 Flutter SDK 2.将文件解压到目标路径, 比如:

cd ~/development
unzip ~/Downloads/flutter_macos_2.8.1-stable.zip

3.配置 flutter 的 PATH 环境变量，mac下zshrc和bash_profile配置 vim ~/.zshrc source ~/.zshrc生效

export FLUTTER_HOME=/Usr/flutter // 解压的文件路径
export PATH=$PATH:$FLUTTER_HOME/bin

4.执行 flutter doctor有可能会出现下面问题

[!] Xcode - develop for iOS and macOS (Xcode 13.2.1)
    ✗ CocoaPods not installed.

sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer
sudo xcodebuild -license
sudo gem install cocoapods


[!] Flutter (Channel stable, 2.8.1, on macOS 11.4 20F71 darwin-arm, locale zh-Hans-CN)
    ✗ Downloaded executables cannot execute on host.
      See https://github.com/flutter/flutter/issues/6207 for more information

需要 rm -rf ~/flutter/bin/cache 缓存 再执行 flutter doctor

[!] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
    ✗ cmdline-tools component is missing

执行flutter doctor –android-licenses如果出现

> Android sdkmanager not found. Update to the latest Android SDK and ensure that the cmdline-tools are

解决方法：Appearance Behavior=>System Settings=>Android SDK=>SDK Tools 列表中选中Android SDK Command-line Tools ( latest ) 下载

Warning: Mapping new ns http://schemas.android.com/repository/android/common/02 to old ns http://sch

解决方式：在项目的两个位置更新了 Gradle： android/build.gradle

buildscript {
    repositories {
        google()
        mavenCentral()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:7.0.2' // Update this line
        ...
    }
}

注意：Gradle 7.0.2 是目前 Google Maven 存储库中最新的稳定版本。要检查更新的版本，请访问https://maven.google.com。在com.android.tools.build > gradle 下，您将找到适用于 Android 的版本。 android/gradle/wrapper/gradle-wrapper.properties

distributionUrl=https\://services.gradle.org/distributions/gradle-7.2-all.zip # Update this line

这次在这两个地方更新 Gradle 解决了这个问题 Flutter报错之Waiting for another flutter command to release the startup lock解决方案 以及flutter doctor卡死问题 关闭Android Studio 打开flutter安装目录/bin/cache 删除lockfile文件 mac下

killall -9 dart Windows下 taskkill /F /IM dart.exe

学习地址&工具

https://javiercbk.github.io/json_to_dart/ 自动生成模型类

http://github.com/drawcall/c2f css转flutter