Flutter Amazon S3与Cognito集成插件amazon_s3_cognito的使用

插件简介

amazon_s3_cognito是为Flutter编写的非官方Amazon S3插件，允许开发者轻松地将AWS Cognito和S3服务集成到他们的应用中。该插件由fäm properties维护。

使用方法

添加依赖

要在项目中使用此插件，请在pubspec.yaml文件中添加如下依赖：

dependencies:
  amazon_s3_cognito: '^0.7.9'

确保你的项目支持AndroidX。

示例代码

下面是一个完整的示例demo，展示了如何使用amazon_s3_cognito进行单个文件上传、多个文件上传以及删除文件的操作。

import 'dart:async';
import 'dart:collection';
import 'package:amazon_s3_cognito/amazon_s3_cognito.dart';
import 'package:amazon_s3_cognito/image_data.dart';
import 'package:flutter/material.dart';

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _platformVersion = 'Unknown';

  EventChannel _amazonS3Stream = EventChannel('amazon_s3_cognito_images_upload_steam');
  StreamSubscription? uploadListenerSubscription;

  List<ImageData> filesToUpload = [];

  @override
  void initState() {
    super.initState();
    _listenToFileUpload();
  }

  void _listenToFileUpload() {
    //监听文件上传进度
    uploadListenerSubscription =
        _amazonS3Stream.receiveBroadcastStream().listen((event) {
      LinkedHashMap<Object?, Object?> map = event;
      print(map);
      ImageData imageData = ImageData.fromMap(map);
      //根据返回的对象更新UI
    });
  }

  Future<void> uploadMultipleFileUploads() async {
    String bucketName = "test";
    String cognitoPoolId = "your pool id";
    String bucketRegion = "imageUploadRegion";
    String bucketSubRegion = "Sub region of bucket";

    //可选参数：文件上传的文件夹
    String fileUploadFolder = "folder inside bucket where we want file to be uploaded";

    //模拟三个相同文件的上传
    for (int i = 0; i < 3; i++) {
      String filePath = ""; //待上传文件路径
      ImageData imageData = ImageData("uniqueFileName$i", filePath,
          uniqueId: "uniqueIdToTrackImage$i", imageUploadFolder: fileUploadFolder);
      filesToUpload.add(imageData);
    }

    //是否需要进度更新，仅iOS适用的大文件分段上传设置
    await AmazonS3Cognito.uploadImages(bucketName, cognitoPoolId, bucketRegion,
        bucketSubRegion, filesToUpload, false);
  }

  Future<void> uploadSingleImage() async {
    String bucketName = "test";
    String cognitoPoolId = "your pool id";
    String bucketRegion = "imageUploadRegion";
    String bucketSubRegion = "Sub region of bucket";

    //可选参数：文件上传的文件夹
    String fileUploadFolder = "folder inside bucket where we want file to be uploaded";

    String filePath = ""; //待上传文件路径
    ImageData imageData = ImageData("uniqueFileName", filePath,
        uniqueId: "uniqueIdToTrackImage", imageUploadFolder: fileUploadFolder);

    //结果为亚马逊S3 URL或失败原因
    String? result = await AmazonS3Cognito.upload(
        bucketName, cognitoPoolId, bucketRegion, bucketSubRegion, imageData,
        needMultipartUpload: true);
    //根据上传成功与否更新UI
    print(result);
  }

  Future<void> deleteImage() async {
    String cognitoPoolId = "your pool id";
    String bucketRegion = "imageUploadRegion";
    String bucketSubRegion = "Sub region of bucket";

    //可选参数：文件所在文件夹
    String bucketName = "test";
    String fileUploadFolder = "101/";
    String fileName = "abc.jpg";

    String? result = await AmazonS3Cognito.delete(bucketName, cognitoPoolId,
        fileName, fileUploadFolder, bucketRegion, bucketSubRegion);

    if (result != null) {
      print(result);
    }
  }

  @override
  void dispose() {
    super.dispose();
    uploadListenerSubscription?.cancel();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Plugin example app'),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              ElevatedButton(onPressed: uploadSingleImage, child: Text("上传单个文件")),
              ElevatedButton(onPressed: uploadMultipleFileUploads, child: Text("上传多个文件")),
              ElevatedButton(onPressed: deleteImage, child: Text("删除文件"))
            ],
          ),
        ),
      ),
    );
  }
}

安装指南

Android配置

在AndroidManifest.xml中注册TransferService：

<application>
  <service android:name="com.amazonaws.mobileconnectors.s3.transferutility.TransferService" android:enabled="true" />
</application>

iOS配置

在AppDelegate.swift中添加以下方法以处理后台URL会话事件：

func application(_ application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: @escaping () -> Void) {
  AWSS3TransferUtility.interceptApplication(application, handleEventsForBackgroundURLSession: identifier, completionHandler: completionHandler)
}

更多关于iOS后台传输的信息可以参考官方文档。

注意事项

• 在bucket名称中只发送bucket名称。如果你希望将文件上传到bucket中的某个子文件夹，请不要在bucket名称中包含子文件夹，而是在ImageData.imageUploadFolder中指定。
• 对于iOS平台，当上传文件非常大以至于可能超过1小时时，设置needMultipartUpload为true。

通过以上步骤，你就可以在Flutter应用中集成Amazon S3与Cognito了。如果有任何问题或需要进一步的帮助，请随时提问！