Flutter 实现阿里云OSS图片上传

一.首先获取文件的本地路径。

二.调后台接口返回oss图片上传需要的参数：accessKeyId, accessKeySecret, bucket, endPoint ,securityToken。

三.对数据进行处理，设置请求的参数

四.获取dio请求返回的路径

使用的依赖：

dio: ^5.0.0

crypto: ^3.0.2 #加密处理

intl: ^0.18.0 #国际化 因为请求参数需要设置日期

oss图片上传dart文件如下所示:

import 'dart:collection';
import 'dart:convert';
import 'dart:math';
import 'dart:typed_data';

import 'package:crypto/crypto.dart';
import 'package:dio/dio.dart';
import 'package:intl/intl.dart';

import '../constants/constants.dart';
import 'package:intl/date_symbol_data_local.dart';//intl包下的
String ossAccessKeyId = '替换成自己的accessKeyId';

String ossAccessKeySecret = '替换成自己的accessKeySecret';
// oss设置的bucket的名字
String bucketName = '替换成自己的bucket';
String ossEndPoint = '替换成自己的endPoint';//oss-cn-shanghai.aliyuncs.com
String ossSecurityToken = '替换成自己的securityToken';
String host = "$bucketName.$ossEndPoint";
String url = 'https://$host';
class OssUtil{
  OssUtil._internal();

  factory OssUtil() => _instance;

  static late final OssUtil _instance = OssUtil._internal();
  Future ossUploadImage(Uint8List imageData,String pathName,
      {required String fileType, String? directory = "community"}) async {
    String date = getGMTDateString();
    String contentType = 'image/$fileType';
      //签名相关
      //请求头
      SplayTreeMap treeMap = SplayTreeMap();
      treeMap["Content-Type".toLowerCase()] = contentType.trim();
      treeMap["Content-MD5".toLowerCase()] = "";
      treeMap["Date".toLowerCase()] = date.trim();
      treeMap["x-oss-security-token".toLowerCase()] = ossSecurityToken.trim();
      String headString = "PUT\n";
      treeMap.forEach((key, value) {
        if (key.startsWith("x-oss-")) {
          headString += key;
          headString += ':';
          headString += value;
        } else {
          headString += value;
        }
        headString += '\n';
      });

      String contentString = "/$bucketName/$pathName";
      String contentToSign = headString + contentString;

      List key = utf8.encode(ossAccessKeySecret);
      List data = utf8.encode(contentToSign);
      var signaturePre = Hmac(sha1, key).convert(data).bytes;
      //最后一步，将上述所得进行base64 编码
      String signature = base64.encode(signaturePre);
      String signatureA = "OSS " + ossAccessKeyId + ":" + signature;

      Dio dio = Dio();
      dio.options.responseType = ResponseType.plain;
      dio.interceptors.add(InterceptorsWrapper(onRequest: (options, handler) {
        options.headers["Authorization"] = signatureA;
        options.headers["Host"] = host;
        options.headers["x-oss-security-token"] = ossSecurityToken;
        options.contentType = contentType;
        options.headers["date"] = date;//必须要设置日期 不设置日期报错 403
        handler.next(options);
      }));
      try {
        // 发送请求
        var resultUrl = url + "/$pathName";
        //必须转成这个类型才可以
        Stream> stream = Stream.value(imageData);
        var rep = await dio.put(resultUrl, data: stream);
        // 成功后返回文件访问路径
        return UPLOAD_IMAGE_BASE_URL+"$pathName";
      } catch (e) {
        return '';
      }


  }

  String getRandom(int num) {
    String alphabet = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";
    String left = "";
    for (var i = 0; i < num; i++) {
      left = left + alphabet[Random().nextInt(alphabet.length)];
    }
    return left;
  }
//这个时间必须调用初始化，并且的时间要减去8小时，要不然会报错，服务器时间和请求时间相差太大，因为是GMT时间，所以当前时间我们是东八区的时间，所以相差8小时。
  String getGMTDateString() {
    initializeDateFormatting();
    var date = DateTime.now();
    date = date.subtract(const Duration(hours: 8));//当前时间减去8个小时
    // date = date.add(const Duration(hours: 8));//当前时间加上8个小时
    return DateFormat("EEE, dd MMM yyyy HH:mm:ss 'GMT'", 'en').format(date);
  }
}

此类使用方式：

  stsUploadResponse(File file) async{
    try {
      if (!LoginPrefs(context).isLogin()) {
        LoginPrefs(context).logout();
        Navigator.of(context)
            .pushNamedAndRemoveUntil("login", ModalRoute.withName("login"));
        return;
      }
      StsUploadResponseRequestEntity stsUploadResponseRequestEntity=new StsUploadResponseRequestEntity();
      stsUploadResponseRequestEntity.fileType=1;
      stsUploadResponseRequestEntity.fileName=file.path;
      StsUploadResponseResponseEntity stsUploadResponseResponseEntity =
      await NetWorkWithToken(context).stsUploadResponse(stsUploadResponseRequestEntity);//调接口获取oss需要的参数
      if (stsUploadResponseResponseEntity != null) {
        String accessKeyId=stsUploadResponseResponseEntity.accessKeyId;
        String accessKeySecret=stsUploadResponseResponseEntity.accessKeySecret;
        String securityToken=stsUploadResponseResponseEntity.securityToken;
        String bucket=stsUploadResponseResponseEntity.bucket;
        String endPoint=stsUploadResponseResponseEntity.endPoint;
        String ossFileFullName=stsUploadResponseResponseEntity.ossFileFullName;
        ossAccessKeyId=accessKeyId;
        ossAccessKeySecret=accessKeySecret;
        bucketName=bucket;
        ossEndPoint=endPoint;
        ossSecurityToken=securityToken;
        String fileType=ossFileFullName.substring(ossFileFullName.lastIndexOf('.')+1);
        print(fileType);
        Uint8List imageData;
        imageData=await file.readAsBytes();
        String path=await OssUtil().ossUploadImage(imageData, ossFileFullName,fileType: fileType);
        print('阿里云返回的路径：'+path);
        return path;
      }
    } on DioError catch (e) {
      print(e.message!);
    } finally {}
  }