库 lib

导入核心库

import 'dart:io';

void main() {
  var f = new File('README.md');
  var content = f.readAsStringSync();
  print(content);
}

# Dart 语言学习示例

导入第三方库

• 编写 pubspec.yaml

dependencies:
  dio: ^4.0.6

• 执行拉取包命令

$ dart pub get

• 程序调用

import 'package:dio/dio.dart';

void main() async {
  Dio dio = Dio();
  Response<String> response =
      await dio.get("https://wpapi.ducafecat.tech/products/categories");
  print(response.data);
}

[{"id":34,"name":"Bag","slug":"bag","parent":0,"description":" ......

导入自己的 git 仓库

• 编写 pubspec.yaml

dependencies:
  uuid:
    git:
      url: https://github.com/Daegalus/dart-uuid
      ref: master

• 执行拉取包命令

$ dart pub get

从 master 分支拉取

导入类文件

• phone.dart

class Phone {
  void call() {
    print('Phone is calling...');
  }
}

class Android {
  void playStore() {
    print('Google play store');
  }

  void call() {
    print('Android phone is calling...');
  }
}

class Ios {
  void appleStore() {
    print('Apply store');
  }

  void call() {
    print('Ios phone is calling...');
  }
}

• 实例

import 'package:dart_learn/phone.dart';

void main() {
  var p = Phone();
  p.call();
}

Phone is calling...

前缀&别名

import 'package:dart_learn/phone.dart' as pp;

void main() {
  var p = pp.Android();
  p.call();
  p.playStore();
}

Android phone is calling...
Google play store

筛选包内容

import 'package:dart_learn/phone.dart' show Ios;

void main() {
  var p = Ios();
  p.call();
  p.appleStore();
}

Ios phone is calling...
Apply store

hide 筛掉某几个包
show 只使用某几个包

延迟载入

import 'package:dart_learn/phone.dart' deferred as pp;

Future<void> main() async {
  await pp.loadLibrary();
  var p = pp.Android();
  p.call();
  p.playStore();
}

Android phone is calling...
Google play store

loadLibrary() 方式在需要的时候载入包
可提高程序启动速度
用在不常使用的功能
用在载入时间过长的包