Flutter02之填坑指南

2019-05-05

hello

Flutter是Google推出的移动UI框架, 可以快速在iOS和Android上构建高质量的原生用户界面。

本文主要记录相关Flutter遇到的坑!!!

1、Flutter卡在Running “flutter packages get” in project_name…

当创建项目/运行项目时

1	Running "flutter packages get" in project_name...

官方解决办法

export PUB_HOSTED_URL=https://pub.flutter-io.cn
export FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn

2、Android项目运行时出错

卡在Initializing gradle…

运行时会卡在Initializing gradle..., 此时因为Android项目会用到Gradle, 如果没有FQ,下载速度会非常慢, 此时我们可以在项目中的android/gradle/wrapper/gradle-wrapper.properties中查看gradle版本号以及地址, 我们可以手动下载然后解压到~/.gradle/wrapper/dists/中。

3、卡在Running ‘gradle assembleDebug

运行时会卡在Running 'gradle assembleDebug, 因为Gradle的Maven仓库在国外, 可以使用阿里云的镜像地址。

* 修改项目中`android/build.gradle`文件

buildscript {
    repositories {
        //修改的地方
        //google()
        //jcenter()
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'
    }
}

allprojects {
    repositories {
        //修改的地方
        //google()
        //jcenter()
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
    }
}

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

* 修改Flutter的配置文件, 该文件在`Flutter安装目录/packages/flutter_tools/gradle/flutter.gradle`

buildscript {
    repositories {
        //修改的地方
        //google()
        //jcenter()
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'
    }
}

import 'package:flutter/material.dart';

void main() {
  runApp(Container(
    color: Colors.white,
    child: Center(
      child: Text(
        'Flutter',
        style: TextStyle(
          color: Colors.purple,
          fontSize: 40
        ),
      ),
    ),
  ));
}

错误提示

flutter: The following assertion was thrown building Text("Flutter", inherit: true, color:
flutter: MaterialColor(primary value: Color(0xff9c27b0)), size: 40.0):
flutter: No Directionality widget found.
flutter: RichText widgets require a Directionality widget ancestor.
flutter: The specific widget that could not find a Directionality ancestor was:
flutter:   RichText
flutter: The ownership chain for the affected widget is: "RichText ← Text ← Center ← [root]"
flutter: Typically, the Directionality widget is introduced by the MaterialApp or WidgetsApp widget at the
flutter: top of your application widget tree. It determines the ambient reading direction and is used, for
flutter: example, to determine how to lay out text, how to interpret "start" and "end" values, and to resolve
flutter: EdgeInsetsDirectional, AlignmentDirectional, and other *Directional objects.

错误中提示, 方向性组件找不到, 这是因为外层的Widget无法确定Text的文本排列方向, 所有之类只要给Text添加一个textDirection属性值或者使用Directionality包裹Text, 并设置Directionality的textDirection。

5、Waiting for another flutter command to release the startup lock…或者创建Flutter项目时卡主

可以终止dart进程, 然后重启IDE

#Linux
killall -9 dart

#window
taskkill /F /IM dart.ext

也可以删除flutter安装目录下的bin/cache/lockfile来解决, 然后重启IDE。