Flutter踩坑记录(持续更新中)

Flutter编译问题

1.Flutter编译时一直卡在"Resolving dependencies"

原因：国内被墙的原因

解决方案1：
配置系统环境变量：

• PUB_HOSTED_URL->https://pub.flutter-io.cn
• FLUTTER_STORAGE_BASE_URL->https://storage.flutter-io.cn
  最新的变量地址请访问：https://flutter.io/community/china

解决方案2：
在android目录的build.gradle下添加阿里镜像代理：

buildscript {
    repositories {
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'https://maven.aliyun.com/repository/public' }
        maven { url 'https://maven.aliyun.com/repository/gradle-plugin' }
        google()
        jcenter()
    }

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

allprojects {
    repositories {
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'https://maven.aliyun.com/repository/public' }
        maven { url 'https://maven.aliyun.com/repository/gradle-plugin' }
        google()
        jcenter()
    }
}

解决方案3：
使用翻墙工具构建

2.运行一些开源的项目编辑报错提示Finished with error: FormatException: Bad UTF-8 encoding 0xc3 (at offset 169)

原因：app的release版本找不到keystore文件
解决方案：
找到android->app目录下的build.gradle，找到buildTypes,修改release的signingConfigs.release为debug:

    buildTypes {
        debug {
            signingConfig signingConfigs.debug
        }
        release {
            signingConfig signingConfigs.debug
        }
    }

或者自己重新配置release的签名

Flutter开发问题

1.使用Navigator.push()跳转界面报错：

'Navigator operation requested with a context that does not include a Navigator.\n'
'The context used to push or pop routes from the Navigator must be that of a '
'widget that is a descendant of a Navigator widget.'

原因：传入的context不支持堆栈管理，比如一个类直接继承自StatelessWidget或StatefulWidget，而它本身或父类没有堆栈管理功能。那么这个类是不支持页面跳转的，所以就会报错。要查看是否支持页面跳转，直接进入源码，比如MaterialApp类，它是支持的，那么它的源码里会有对应的功能介绍：

/// See also:
///
///  * [Scaffold], which provides standard app elements like an [AppBar] and a [Drawer].
///  * [Navigator], which is used to manage the app's stack of pages.  //这里做了对应的介绍
///  * [MaterialPageRoute], which defines an app page that transitions in a material-specific way.
///  * [WidgetsApp], which defines the basic app elements but does not depend on the material library.
///  * The Flutter Internationalization Tutorial,
///    <https://flutter.io/tutorials/internationalization/>.
class MaterialApp extends StatefulWidget {
  .....
}

放一个报错的代码：

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
        title: 'Welcome to Flutter',
        home: new Scaffold(
            body:Container(
              child: FlatButton(onPressed:(){
                var push = Navigator.push(context,MaterialPageRoute(builder: (BuildContext context) {
                  return new OtherPager("我是从main传过去的值");
                }));
                push.then((value){
                print("我是从上个页面传递回来的值$value");
                });
              }, child:new Icon(Icons.build)),
            )
        )
    );
  }
}

这里的MyApp是直接继承自StatelessWidget的，而在runApp()中直接使用了它，它没有父类而它本身也不支持界面的跳转，所以用它的context传入到Navigator中肯定是会报错的
解决方案
使用一个有堆栈管理功能的父类将MyApp类包裹，使其具有堆栈跳转功能
见如下代码：

void main() => runApp(MaterialApp(home: MyApp()));

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new Scaffold(
        body: Container(
      child: FlatButton(
          onPressed: () {
            var push = Navigator.push(context,
                MaterialPageRoute(builder: (BuildContext context) {
              return new OtherPager("我是从main传过去的值");
            }));
            push.then((value) {
              print("我是从上个页面传递回来的值$value");
            });
          },
          child: new Icon(Icons.build)),
    ));
  }
}

代码中将MaterialApp移出来了，直接将MyApp包裹了，那么MyApp的context就生效了，代码也不会报错啦。