flutter直接上传文件到阿里云oss

import 'dart:convert';
import 'dart:io';
import 'dart:math';
import 'package:crypto/crypto.dart';
import 'package:dio/dio.dart';

class UploadOss {

  static String ossAccessKeyId = 'ossAccessKeyId';

  static String ossAccessKeySecret = 'ossAccessKeySecret';
  // oss设置的bucket的名字
  static String bucket = 'bucketName';
  // 发送请求的url,根据你自己设置的是哪个城市的
  static String url = 'https://$bucket.oss-cn-hangzhou.aliyuncs.com';

  // 过期时间
  static String expiration = '2025-01-01T12:00:00.000Z';

  /**
   * @params file 要上传的文件对象
   * @params rootDir 阿里云oss设置的根目录文件夹名字
   * @param fileType 文件类型例如jpg,mp4等
   * @param callback 回调函数我这里用于传cancelToken，方便后期关闭请求
   * @param onSendProgress 上传的进度事件
   */

  static Future upload({ File file , String rootDir = 'moment', String fileType, Function callback, Function onSendProgress}) async {
    String policyText = '{"expiration": "$expiration","conditions": [{"bucket": "$bucket" },["content-length-range", 0, 1048576000]]}';

    // 获取签名
    String signature = getSignature(policyText);

    BaseOptions options = new BaseOptions();
    options.responseType = ResponseType.plain;

    //创建dio对象
    Dio dio = new Dio(options);
    // 生成oss的路径和文件名我这里目前设置的是moment/20201229/test.mp4
    String pathName = '$rootDir/${getDate()}/${getRandom(12)}.${fileType == null ? getFileType(file.path) : fileType}';

    // 请求参数的form对象
    FormData data = new FormData.fromMap({
      'key': pathName,
      'policy': getSplicyBase64(policyText),
      'OSSAccessKeyId': ossAccessKeyId,
      'success_action_status': '200', //让服务端返回200，不然，默认会返回204
      'signature': signature,
      'contentType': 'multipart/form-data',
      'file': MultipartFile.fromFileSync(file.path),
    });

    Response response;
    CancelToken uploadCancelToken = CancelToken();
    callback ?? callback(uploadCancelToken);

    try {
      // 发送请求
      response = await dio.post(url, data: data, cancelToken: uploadCancelToken, onSendProgress: (int count, int data) {
        onSendProgress(count, data);
      });
      // 成功后返回文件访问路径
      return '$url/$pathName';
    } catch(e) {
      throw(e.message);
    }

  }


  /*
  * 生成固定长度的随机字符串
  * */
  static String getRandom(int num) {
    String alphabet = 'qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM';
    String left = '';
    for (var i = 0; i < num; i++) {
//    right = right + (min + (Random().nextInt(max - min))).toString();
      left = left + alphabet[Random().nextInt(alphabet.length)];
    }
    return left;
  }
  /*
  * 根据图片本地路径获取图片名称
  * */
  static String getImageNameByPath(String filePath) {
    // ignore: null_aware_before_operator
    return filePath?.substring(filePath?.lastIndexOf("/")+1,filePath?.length);
  }
  /**
   * 获取文件类型
   */
  static String getFileType(String path) {
    print(path);
    List array = path.split('.');
    return array[array.length -1];
  }
  /// 获取日期
  static String getDate() {
    DateTime now = DateTime.now();
    return '${now.year}${now.month}${now.day}';
  }

  // 获取plice的base64
  static getSplicyBase64(String policyText) {
    //进行utf8编码
    List policyText_utf8 = utf8.encode(policyText);
    //进行base64编码
    String policy_base64 = base64.encode(policyText_utf8);
    return policy_base64;
  }

  /// 获取签名
  static String getSignature(String policyText) {
    //进行utf8编码
    List policyText_utf8 = utf8.encode(policyText);
    //进行base64编码
    String policy_base64 = base64.encode(policyText_utf8);
    //再次进行utf8编码
    List policy = utf8.encode(policy_base64);
    //进行utf8 编码
    List key = utf8.encode(ossAccessKeySecret);
    //通过hmac,使用sha1进行加密
    List signature_pre = Hmac(sha1, key).convert(policy).bytes;
    //最后一步，将上述所得进行base64 编码
    String signature = base64.encode(signature_pre);
    return signature;
  }
}

Future uploadFile(File file, { Function onSendProgress, Function callback}) async {
  final String url = await UploadOss.upload(file: file, onSendProgress: onSendProgress, callback: callback);
  return url;
}

// 通过ossServerUrl直接get获取到如下数据
{
        "StatusCode": 200,
          "AccessKeyId": "STS.NSsrKZes4cqm.....",
          "AccessKeySecret": "7eGnLZaEFsRCGYJAnrtdE9n.....",
          "Expiration": "2020-04-08T03:44:21Z",
          "SecurityToken": "CAISlQJ1q6Ft5B2y....."
  }
 
//表单需要的参数: AccessKeyId、AccessKeySecret、SecurityToken;
FormData formdata = new FormData.from({
        //文件名，随意
        'Filename': OssUtil.instance.getImageName(filePath),
        //"可以填写文件夹名（对应于oss服务中的文件夹）/" + fileName
        'key': uploadName,//上传后的文件名
        'policy': OssUtil.policy,
        //Bucket 拥有者的AccessKeyId。
        'OSSAccessKeyId': data['AccessKeyId'],
        //让服务端返回200，不然，默认会返回204
        'success_action_status': '200',
        'signature': OssUtil.instance.getSignature(data['AccessKeySecret']),
        //临时用户授权时必须，需要携带后台返回的security-token
        'x-oss-security-token': data['SecurityToken'],
        'file': new UploadFileInfo(
            file, OssUtil.instance.getImageNameByPath(filePath))
        //必须放在参数最后
   });
//然后通过存储地址直接把表单(formdata)上传上去;
Dio dio=Dio();
dio.options.responseType=ResponseType.plain;
Response response=awaitdio.post(,data:formData);
......

import 'dart:convert';
import 'package:crypto/crypto.dart';
import 'dart:math';
 
class OssUtil {
 获取
  //验证文本域
  static String _policyText =
      '{"expiration": "2069-05-22T03:15:00.000Z","conditions": [["content-length-range", 0, 1048576000]]}';//UTC时间+8=北京时间
 
  //进行utf8编码
  // ignore: non_constant_identifier_names
  static List _policyText_utf8 = utf8.encode(_policyText);
  //进行base64编码
  static String policy= base64.encode(_policyText_utf8);
 
  //再次进行utf8编码
  // ignore: non_constant_identifier_names
  static List _policy_utf8 = utf8.encode(policy);
 
  // 工厂模式
  factory OssUtil() => _getInstance();
 
  static OssUtil get instance => _getInstance();
  static OssUtil _instance;
 
  OssUtil._internal();
 
  static OssUtil _getInstance() {
    if (_instance == null) {
      _instance = new OssUtil._internal();
    }
    return _instance;
  }
 
  /*
  *获取signature签名参数
  */
  String getSignature(String _accessKeySecret){
    //进行utf8 编码
    // ignore: non_constant_identifier_names
    List AccessKeySecretUtf8 = utf8.encode(_accessKeySecret);
    //通过hmac,使用sha1进行加密
    List signaturePre = new Hmac(sha1, AccessKeySecretUtf8).convert(_policy_utf8).bytes;
    //最后一步，将上述所得进行base64 编码
    String signature = base64.encode(signaturePre);
    return signature;
  }
 
  // ignore: slash_for_doc_comments
  /**
   * 生成上传上传图片的名称 ,获得的格式:photo/20171027175940_oCiobK
   * 可以定义上传的路径uploadPath(Oss中保存文件夹的名称)
   * @param uploadPath 上传的路径 如：/photo
   * @return photo/20171027175940_oCiobK
   */
  String getImageUploadName(String uploadPath,String filePath) {
    String imageMame = "";
    var timestamp = new DateTime.now().millisecondsSinceEpoch;
    imageMame =timestamp.toString()+"_"+getRandom(6);
    if(uploadPath!=null&&uploadPath.isNotEmpty){
      imageMame=uploadPath+"/"+imageMame;
    }
    String imageType=filePath?.substring(filePath?.lastIndexOf("."),filePath?.length);
    return imageMame+imageType;
  }
 
  String getImageName(String filePath) {
    String imageMame = "";
    var timestamp = new DateTime.now().millisecondsSinceEpoch;
    imageMame =timestamp.toString()+"_"+getRandom(6);
    String imageType=filePath?.substring(filePath?.lastIndexOf("."),filePath?.length);
    return imageMame+imageType;
  }
 
  /*
  * 生成固定长度的随机字符串
  * */
  String getRandom(int num) {
    String alphabet = 'qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM';
    String left = '';
    for (var i = 0; i < num; i++) {
//    right = right + (min + (Random().nextInt(max - min))).toString();
      left = left + alphabet[Random().nextInt(alphabet.length)];
    }
    return left;
  }
 
  /*
  * 根据图片本地路径获取图片名称
  * */
  String getImageNameByPath(String filePath) {
    // ignore: null_aware_before_operator
    return filePath?.substring(filePath?.lastIndexOf("/")+1,filePath?.length);
  }
}