通过服务端签名限制上传文件类型和大小-对象存储-阿里云

用户上传过大文件或恶意文件，会占用OSS大量的存储空间和带宽资源，甚至导致OSS的域名在某些环境下被封禁。OSS不直接提供限制上传文件类型和大小的功能，但您可以借助服务端生成签名时指定文件类型及大小，或在客户端自行编写拦截逻辑来实现。

服务端生成Post签名和PostPolicy

对于需要限制上传文件属性的场景，您可以在服务端生成PostObject所需的Post签名、PostPolicy等信息，然后客户端可以凭借这些信息，在一定的限制下不依赖OSS SDK直接上传文件。您可以借助服务端生成的PostPolicy限制客户端上传的文件，例如限制文件大小、文件类型。此方案适用于通过HTML表单上传的方式上传文件。需要注意的是，此方案不支持基于分片上传大文件、基于分片断点续传的场景。更多信息，请参见PostObject。

示例代码

服务端示例代码

服务端生成Post签名和Post Policy等信息的示例代码如下：

说明

当前代码支持一键部署，您可以直接在函数计算FC中一键部署本代码。oss-upload-post-signature-app

Python

import os
from hashlib import sha1 as sha
import json
import base64
import hmac
import datetime
import time

# 配置环境变量OSS_ACCESS_KEY_ID。
access_key_id = os.environ.get('OSS_ACCESS_KEY_ID')
# 配置环境变量OSS_ACCESS_KEY_SECRET。
access_key_secret = os.environ.get('OSS_ACCESS_KEY_SECRET')
# 将<YOUR_BUCKET>替换为Bucket名称。
bucket = '<YOUR_BUCKET>'
# host的格式为bucketname.endpoint。将<YOUR_BUCKET>替换为Bucket名称。将<YOUR_ENDPOINT>替换为OSS Endpoint，例如oss-cn-hangzhou.aliyuncs.com。
host = 'https://<YOUR_BUCKET>.<YOUR_ENDPOINT>'
# 指定上传到OSS的文件前缀。
upload_dir = 'user-dir-prefix/'
# 指定过期时间，单位为秒。
expire_time = 3600


def generate_expiration(seconds):
    """
    通过指定有效的时长（秒）生成过期时间。
    :param seconds: 有效时长（秒）。
    :return: ISO8601 时间字符串，如："2014-12-01T12:00:00.000Z"。
    """
    now = int(time.time())
    expiration_time = now + seconds
    gmt = datetime.datetime.utcfromtimestamp(expiration_time).isoformat()
    gmt += 'Z'
    return gmt


def generate_signature(access_key_secret, expiration, conditions, policy_extra_props=None):
    """
    生成签名字符串Signature。
    :param access_key_secret: 有权限访问目标Bucket的AccessKeySecret。
    :param expiration: 签名过期时间，按照ISO8601标准表示，并需要使用UTC时间，格式为yyyy-MM-ddTHH:mm:ssZ。示例值："2014-12-01T12:00:00.000Z"。
    :param conditions: 策略条件，用于限制上传表单时允许设置的值。
    :param policy_extra_props: 额外的policy参数，后续如果policy新增参数支持，可以在通过dict传入额外的参数。
    :return: signature，签名字符串。
    """
    policy_dict = {
        'expiration': expiration,
        'conditions': conditions
    }
    if policy_extra_props is not None:
        policy_dict.update(policy_extra_props)
    policy = json.dumps(policy_dict).strip()
    policy_encode = base64.b64encode(policy.encode())
    h = hmac.new(access_key_secret.encode(), policy_encode, sha)
    sign_result = base64.b64encode(h.digest()).strip()
    return sign_result.decode()

def generate_upload_params():
    policy = {
        # 有效期。
        "expiration": generate_expiration(expire_time),
        # 约束条件。
        "conditions": [
            # 未指定success_action_redirect时，上传成功后的返回状态码，默认为 204。
            ["eq", "$success_action_status", "200"],
            # 表单域的值必须以指定前缀开始。例如指定key的值以user/user1开始，则可以写为["starts-with", "$key", "user/user1"]。
            ["starts-with", "$key", upload_dir],
            # 限制上传Object的最小和最大允许大小，单位为字节。
            ["content-length-range", 1, 1000000],
            # 限制上传的文件为指定的图片类型
            ["in", "$content-type", ["image/jpg", "image/png"]]
        ]
    }
    signature = generate_signature(access_key_secret, policy.get('expiration'), policy.get('conditions'))
    response = {
        'policy': base64.b64encode(json.dumps(policy).encode('utf-8')).decode(),
        'ossAccessKeyId': access_key_id,
        'signature': signature,
        'host': host,
        'dir': upload_dir
        # 可以在这里再自行追加其他参数
    }
    return json.dumps(response)

Java

package com.aliyun.sample;

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.common.utils.BinaryUtil;
import com.aliyun.oss.model.MatchMode;
import com.aliyun.oss.model.PolicyConditions;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.codehaus.jettison.json.JSONObject;
import java.util.Date;

@Controller
public class PostSignatureController {
    @Autowired
    private OSS ossClient;

    @Autowired
    private OssConfig ossConfig;

    @GetMapping("/get_post_signature_for_oss_upload")
    @ResponseBody
    public String generatePostSignature() {
        JSONObject response = new JSONObject();
        try {
            long expireEndTime = System.currentTimeMillis() + ossConfig.getExpireTime() * 1000;
            Date expiration = new Date(expireEndTime);
            PolicyConditions policyConds = new PolicyConditions();
            policyConds.addConditionItem(PolicyConditions.COND_CONTENT_LENGTH_RANGE, 0, 1048576000);
            policyConds.addConditionItem(MatchMode.StartWith, PolicyConditions.COND_KEY, ossConfig.getDir());
            String postPolicy = ossClient.generatePostPolicy(expiration, policyConds);
            byte[] binaryData = postPolicy.getBytes("utf-8");
            String encodedPolicy = BinaryUtil.toBase64String(binaryData);
            String postSignature = ossClient.calculatePostSignature(postPolicy);
            response.put("ossAccessKeyId", ossConfig.getAccessKeyId());
            response.put("policy", encodedPolicy);
            response.put("signature", postSignature);
            response.put("dir", ossConfig.getDir());
            response.put("host", ossConfig.getHost());
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("HTTP Status Code: " + oe.getRawResponseError());
            System.out.println("Error Message: " + oe.getErrorMessage());
            System.out.println("Error Code:       " + oe.getErrorCode());
            System.out.println("Request ID:      " + oe.getRequestId());
            System.out.println("Host ID:           " + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message: " + ce.getMessage());
        } catch (Exception e) {
            System.out.println("Caught an unexpected exception: " + e.getMessage());
        }
        return response.toString();
    }
}

Go

package main

import (
	"crypto/hmac"
	"crypto/sha1"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"time"
)

var (
	// 配置环境变量OSS_ACCESS_KEY_ID。
	accessKeyId = os.Getenv("OSS_ACCESS_KEY_ID")
	// 配置环境变量OSS_ACCESS_KEY_SECRET。
	accessKeySecret = os.Getenv("OSS_ACCESS_KEY_SECRET")
	// host的格式为bucketname.endpoint。将${your-bucket}替换为Bucket名称。将${your-endpoint}替换为OSS Endpoint，例如oss-cn-hangzhou.aliyuncs.com。
	host = "http://${your-bucket}.${your-endpoint}"
	// 指定上传到OSS的文件前缀。
	uploadDir = "user-dir-prefix/"
	// 指定过期时间，单位为秒。
	expireTime = int64(3600)
)

type ConfigStruct struct {
	Expiration string          `json:"expiration"`
	Conditions [][]interface{} `json:"conditions"`
}

type PolicyToken struct {
	AccessKeyId string `json:"ossAccessKeyId"`
	Host        string `json:"host"`
	Signature   string `json:"signature"`
	Policy      string `json:"policy"`
	Directory   string `json:"dir"`
}

func getGMTISO8601(expireEnd int64) string {
	return time.Unix(expireEnd, 0).UTC().Format("2006-01-02T15:04:05Z")
}

func getPolicyToken() string {
	now := time.Now().Unix()
	expireEnd := now + expireTime
	tokenExpire := getGMTISO8601(expireEnd)

	var config ConfigStruct
	config.Expiration = tokenExpire

	// 添加文件前缀限制
	config.Conditions = append(config.Conditions, []interface{}{"starts-with", "$key", uploadDir})

	// 添加文件大小限制，例如1KB到10MB
	minSize := int64(1024)
	maxSize := int64(10 * 1024 * 1024)
	config.Conditions = append(config.Conditions, []interface{}{"content-length-range", minSize, maxSize})

	result, err := json.Marshal(config)
	if err != nil {
		fmt.Println("callback json err:", err)
		return ""
	}

	encodedResult := base64.StdEncoding.EncodeToString(result)
	h := hmac.New(sha1.New, []byte(accessKeySecret))
	io.WriteString(h, encodedResult)
	signedStr := base64.StdEncoding.EncodeToString(h.Sum(nil))

	policyToken := PolicyToken{
		AccessKeyId: accessKeyId,
		Host:        host,
		Signature:   signedStr,
		Policy:      encodedResult,
		Directory:   uploadDir,
	}

	response, err := json.Marshal(policyToken)
	if err != nil {
		fmt.Println("json err:", err)
		return ""
	}

	return string(response)
}

func handler(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path == "/" {
		http.ServeFile(w, r, "templates/index.html")
		return
	} else if r.URL.Path == "/get_post_signature_for_oss_upload" {
		policyToken := getPolicyToken()
		w.Header().Set("Content-Type", "application/json")
		w.Write([]byte(policyToken))
		return
	}
	http.NotFound(w, r)
}

func main() {
	http.HandleFunc("/", handler)
	http.ListenAndServe(":8080", nil)
}

PHP

<?php
function gmt_iso8601($time)
{
    return str_replace('+00:00', '.000Z', gmdate('c', $time));
}

// 从环境变量中获取访问凭证。运行本示例代码之前，请确保已设置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID和ALIBABA_CLOUD_ACCESS_KEY_SECRET。
$accessKeyId = getenv("ALIBABA_CLOUD_ACCESS_KEY_ID");
$accessKeySecret = getenv("ALIBABA_CLOUD_ACCESS_KEY_SECRET");
// $host的格式为<YOUR-BUCKET>.<YOUR-ENDPOINT>'，请替换为您的真实信息。
$host = 'http://<YOUR-BUCKET>.<YOUR-ENDPOINT>';
// 用户上传文件时指定的前缀。
$dir = 'user-dir-prefix/';          

$now = time();
//设置该policy超时时间是10s. 即这个policy过了这个有效时间，将不能访问。
$expire = 30;  
$end = $now + $expire;
$expiration = gmt_iso8601($end);

//最大文件大小.用户可以自己设置。
$condition = array(0 => 'content-length-range', 1 => 0, 2 => 1048576000);
$conditions[] = $condition;

// 表示用户上传的数据，必须是以$dir开始，不然上传会失败，这一步不是必须项，只是为了安全起见，防止用户通过policy上传到别人的目录。
$start = array(0 => 'starts-with', 1 => '$key', 2 => $dir);
$conditions[] = $start;


$arr = array('expiration' => $expiration, 'conditions' => $conditions);
$policy = json_encode($arr);
$base64_policy = base64_encode($policy);
$string_to_sign = $base64_policy;
$signature = base64_encode(hash_hmac('sha1', $string_to_sign, $accessKeySecret, true));

$response = array();
$response['ossAccessKeyId'] = $accessKeyId;
$response['host'] = $host;
$response['policy'] = $base64_policy;
$response['signature'] = $signature;
$response['dir'] = $dir;  
echo json_encode($response);

Node.js

const express = require("express");
const { Buffer } = require("buffer");
const OSS = require("ali-oss");
const app = express();
const path = require("path");
const config = {
  // 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID。
  accessKeyId: process.env.ALIBABA_CLOUD_ACCESS_KEY_ID,
  // 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_SECRET。
  accessKeySecret: process.env.ALIBABA_CLOUD_ACCESS_KEY_SECRET,
  // 将<YOUR-BUCKET>替换为Bucket名称。
  bucket: "<YOUR-BUCKET>",
  // 指定上传到OSS的文件前缀。
  dir: "prefix/",
};

app.use(express.static(path.join(__dirname, "templates")));

app.get("/get_post_signature_for_oss_upload", async (req, res) => {
  const client = new OSS(config);
  const date = new Date();
  // 设置签名的有效期，单位为秒。
  date.setSeconds(date.getSeconds() + 3600);
  const policy = {
    expiration: date.toISOString(),
    conditions: [
      // 设置上传文件的大小限制。
      ["content-length-range", 0, 1048576000],
      // 限制可上传的Bucket。
      { bucket: client.options.bucket },
    ],
  };
  const formData = await client.calculatePostSignature(policy);
  const host = `http://${config.bucket}.${
    (await client.getBucketLocation()).location
  }.aliyuncs.com`.toString();
  const params = {
    policy: formData.policy,
    signature: formData.Signature,
    ossAccessKeyId: formData.OSSAccessKeyId,
    host,
    dir: config.dir,
  };
  res.json(params);
});

app.get(/^(.+)*\.(html|js)$/i, async (req, res) => {
  res.sendFile(path.join(__dirname, "./templates", req.originalUrl));
});

app.listen(8000, () => {
  console.log("http://127.0.0.1:8000");
});

Ruby

require 'sinatra'
require 'base64'
require 'open-uri'
require 'cgi'
require 'openssl'
require 'json'
require 'sinatra/reloader'
require 'sinatra/content_for'

# 设置public文件夹路径为当前文件夹下的templates文件夹
set :public_folder, File.dirname(__FILE__) + '/templates'

# 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID。
$access_key_id = ENV['ALIBABA_CLOUD_ACCESS_ID']
# 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_SECRET。
$access_key_secret = ENV['ALIBABA_CLOUD_ACCESS_SECRET']

# $host的格式为<bucketname>.<endpoint>，请替换为您的真实信息。
$host = 'http://<bucketname>.<endpoint>';

# 用户上传文件时指定的前缀。
$upload_dir = 'user-dir-prefix/'
# 过期时间，单位为秒。
$expire_time = 30
$server_ip = "0.0.0.0"
$server_port = 8000

if ARGV.length == 1 
  $server_port = ARGV[0]
elsif ARGV.length == 2
  $server_ip = ARGV[0]
  $server_port = ARGV[1]
end

puts "App server is running on: http://#{$server_ip}:#{$server_port}"

def hash_to_jason(source_hash)
  jason_string = source_hash.to_json;    

  jason_string.gsub!("\":[", "\": [")
  jason_string.gsub!("\",\"", "\", \"")
  jason_string.gsub!("],\"", "], \"")
  jason_string.gsub!("\":\"", "\": \"")

  jason_string
end


def get_token()
  expire_syncpoint = Time.now.to_i + $expire_time
  expire = Time.at(expire_syncpoint).utc.iso8601()
  response.headers['expire'] = expire
  policy_dict = {}
  condition_arrary = Array.new
  array_item = Array.new
  array_item.push('starts-with')
  array_item.push('$key')
  array_item.push($upload_dir)
  condition_arrary.push(array_item)
  policy_dict["conditions"] = condition_arrary
  policy_dict["expiration"] = expire
  policy = hash_to_jason(policy_dict)
  policy_encode = Base64.strict_encode64(policy).chomp;
  h = OpenSSL::HMAC.digest('sha1', $access_key_secret, policy_encode)
  hs = Digest::MD5.hexdigest(h)
  sign_result = Base64.strict_encode64(h).strip()
  token_dict = {}
  token_dict['ossAccessKeyId'] = $access_key_id
  token_dict['host'] = $host
  token_dict['policy'] = policy_encode
  token_dict['signature'] = sign_result 
  token_dict['expire'] = expire_syncpoint
  token_dict['dir'] = $upload_dir
  result = hash_to_jason(token_dict)
  result
end

set :bind, $server_ip
set :port, $server_port

get '/get_post_signature_for_oss_upload' do
  token = get_token()
  puts "Token: #{token}"
  token
end

get '/*' do
  puts "********************* GET "
  send_file File.join(settings.public_folder, 'index.html')
end

end

if ARGV.length == 1 
  $server_port = ARGV[0]
elsif ARGV.length == 2
  $server_ip = ARGV[0]
  $server_port = ARGV[1]
end

$server_ip = "0.0.0.0"
$server_port = 8000

puts "App server is running on: http://#{$server_ip}:#{$server_port}"

set :bind, $server_ip
set :port, $server_port

get '/get_sts_token_for_oss_upload' do
  token = get_sts_token_for_oss_upload()
  response = {
    "AccessKeyId" => token["Credentials"]["AccessKeyId"],
    "AccessKeySecret" => token["Credentials"]["AccessKeySecret"],
    "SecurityToken" => token["Credentials"]["SecurityToken"]
  }
  response.to_json
end

get '/*' do
  puts "********************* GET "
  send_file File.join(settings.public_folder, 'index.html')
end

C#

using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.AspNetCore.Http;
using System.IO;
using System.Collections.Generic;
using System;
using System.Globalization;
using System.Text;
using System.Security.Cryptography;
using Newtonsoft.Json;
using Microsoft.AspNetCore.Http.Extensions;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

namespace YourNamespace
{
    public class Program
    {
        private ILogger<Program> _logger;
        // 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID。
        public string AccessKeyId { get; set; } = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID");
        // 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_SECRET。
        public string AccessKeySecret { get; set; } = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET");
        // host的格式为bucketname.endpoint。将<YOUR-BUCKET>替换为Bucket名称。将<YOUR-ENDPOINT>替换为OSS Endpoint，例如oss-cn-hangzhou.aliyuncs.com。
        public string Host { get; set; } = "<YOUR-BUCKET>.<YOUR-ENDPOINT>";
        // 指定上传到OSS的文件前缀。
        public string UploadDir { get; set; } = "user-dir-prefix/";
        // 指定过期时间，单位为秒。
        public int ExpireTime { get; set; } = 3600;
        public class PolicyConfig
        {
            public string expiration { get; set; }
            public List<List<object>> conditions { get; set; }
        }
        public class PolicyToken
        {
            public string Accessid { get; set; }
            public string Policy { get; set; }
            public string Signature { get; set; }
            public string Dir { get; set; }
            public string Host { get; set; }
            public string Expire { get; set; }
        }
        public static void Main(string[] args)
        {
            var builder = WebApplication.CreateBuilder(args);
            var app = builder.Build();

            builder.Logging.AddConsole();
            var logger = builder.Services.BuildServiceProvider().GetRequiredService<ILogger<Program>>();

            app.UseStaticFiles(); 

            app.MapGet("/", async (context) =>
            {
                var filePath = Path.Combine(Directory.GetCurrentDirectory(), "templates/index.html");
                var htmlContent = await File.ReadAllTextAsync(filePath);
                await context.Response.WriteAsync(htmlContent);
                logger.LogInformation("GET request to root path");
            });

            app.MapGet("/get_post_signature_for_oss_upload", async (context) =>
            {
                var program = new Program(logger);
                var token = program.GetPolicyToken();

                logger.LogInformation($"Token: {token}");

                context.Response.ContentType = "application/json";
                await context.Response.WriteAsync(token);
            });

            app.Run();
        }

        public Program(ILogger<Program> logger)
        {
            _logger = logger;
        }

        private string ToUnixTime(DateTime dateTime)
        {
            return ((DateTimeOffset)dateTime).ToUnixTimeSeconds().ToString();
        }

        private string GetPolicyToken()
        {
            var expireDateTime = DateTime.Now.AddSeconds(ExpireTime);
            var config = new PolicyConfig
            {
                expiration = FormatIso8601Date(expireDateTime),
                conditions = new List<List<object>>()
            };
            config.conditions.Add(new List<object>
            {
                "content-length-range", 0, 1048576000
            });
            var policy = JsonConvert.SerializeObject(config);
            var policyBase64 = EncodeBase64("utf-8", policy);
            var signature = ComputeSignature(AccessKeySecret, policyBase64);
            var policyToken = new PolicyToken
            {
                Accessid = AccessKeyId,
                Host = Host,
                Policy = policyBase64,
                Signature = signature,
                Expire = ToUnixTime(expireDateTime),
                Dir = UploadDir
            };
            return JsonConvert.SerializeObject(policyToken);
        }

        private string FormatIso8601Date(DateTime dtime)
        {
            return dtime.ToUniversalTime().ToString("yyyy-MM-dd'T'HH:mm:ss.fff'Z'",
                                    CultureInfo.CurrentCulture);
        }

        private string EncodeBase64(string codeType, string code)
        {
            string encode = "";
            byte[] bytes = Encoding.GetEncoding(codeType).GetBytes(code);
            try
            {
                encode = Convert.ToBase64String(bytes);
            }
            catch
            {
                encode = code;
            }
            return encode;
        }

        private string ComputeSignature(string key, string data)
        {
            using (var algorithm = new HMACSHA1(Encoding.UTF8.GetBytes(key)))
            {
                return Convert.ToBase64String(algorithm.ComputeHash(Encoding.UTF8.GetBytes(data)));
            }
        }
    }
}

客户端示例代码

Web端使用Post签名和Post Policy等信息上传文件到OSS的示例代码如下：

JavaScript

const form = document.querySelector("form");
const fileInput = document.querySelector("#file");
form.addEventListener("submit", (event) => {
  event.preventDefault();
  const file = fileInput.files[0];
  if (!fileInput.files[0]) {
    alert('请选择要上传的文件');
    return;
  }
  const filename = fileInput.files[0].name;
  fetch("/get_post_signature_for_oss_upload", { method: "GET" })
    .then((response) => {
      if (!response.ok) {
        throw new Error("获取签名失败");
      }
      return response.json();
    })
    .then((data) => {
      const formData = new FormData();
      formData.append("name", filename);
      formData.append("policy", data.policy);
      formData.append("OSSAccessKeyId", data.ossAccessKeyId);
      formData.append("success_action_status", "200");
      formData.append("signature", data.signature);
      formData.append("key", data.dir + filename);
      formData.append("file", file);

      return fetch(data.host, { method: "POST", body: formData });
    })
    .then((response) => {
      if (response.ok) {
        console.log("上传成功");
        alert("文件已上传");
      } else {
        console.log("上传失败", response);
        alert("上传失败，请稍后再试");
      }
    })
    .catch((error) => {
      console.error("发生错误:", error);
    });
});

服务端生成签名URL

生成签名URL时，不支持指定content-length-range，因此不适用于限制上传文件大小的场景。对于要限制上传文件类型的场景，您可以在服务端生成签名URL时，强制指定content-type，客户端凭借签名URL上传文件时，必须上传指定类型的文件。更多信息，请参见签名版本1。

示例代码

服务端示例代码

服务端生成签名URL的示例代码如下：

说明

当前代码支持一键部署，您可以直接在函数计算FC中一键部署本代码。oss-upload-presigned-url-app

Python

import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider

# 从环境变量中获取访问凭证。运行本示例代码之前，请确保已设置环境变量OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
auth = oss2.ProviderAuth(EnvironmentVariableCredentialsProvider())
# 将<YOUR_ENDPOINT>替换为Bucket所在地域对应的Endpoint。以华东1（杭州）为例，Endpoint填写为https://oss-cn-hangzhou.aliyuncs.com。
# 将<YOUR_BUCKET>替换为Bucket名称。
bucket = oss2.Bucket(auth, '<YOUR_ENDPOINT>', '<YOUR_BUCKET>')
# 指定过期时间，单位秒。
expire_time = 3600
# 填写Object完整路径，例如exampledir/exampleobject.png。Object完整路径中不能包含Bucket名称。
object_name = 'exampledir/exampleobject.png'

def generate_presigned_url():
    # 指定Header。
    headers = dict()
    # 指定Content-Type。
    headers['Content-Type'] = 'image/png'
    # 指定存储类型。
    # headers["x-oss-storage-class"] = "Standard"
    # 生成签名URL时，OSS默认会对Object完整路径中的正斜线（/）进行转义，从而导致生成的签名URL无法直接使用。
    # 设置slash_safe为True，OSS不会对Object完整路径中的正斜线（/）进行转义，此时生成的签名URL可以直接使用。
    url = bucket.sign_url('PUT', object_name, expire_time, slash_safe=True, headers=headers)
    return url

Java

import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Bean;
import com.aliyun.oss.HttpMethod;
import com.aliyun.oss.model.GeneratePresignedUrlRequest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.net.URL;
import java.util.Date;
import javax.annotation.PreDestroy;

@Configuration
public class OssConfig {

    /**
     * 将<your-endpoint>替换为OSS Endpoint，例如oss-cn-hangzhou.aliyuncs.com。
     */
    private static final String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";

    /**
     * 通过环境变量 ALIBABA_CLOUD_ACCESS_KEY_ID 设置 accessKeyId
     */
    @Value("${ALIBABA_CLOUD_ACCESS_KEY_ID}")
    private String accessKeyId;

    /**
     * 通过环境变量 ALIBABA_CLOUD_ACCESS_KEY_Secret 设置 accessKeySecret
     */
    @Value("${ALIBABA_CLOUD_ACCESS_KEY_SECRET}")
    private String accessKeySecret;

    private OSS ossClient;


    @Bean
    public OSS getSssClient() {
        ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);
        return ossClient;
    }

    @PreDestroy
    public void onDestroy() {
        ossClient.shutdown();
    }
}

@Controller
public class PresignedURLController {

    /**
     * 将<your-bucket>替换为Bucket名称。
     * 指定上传到OSS的文件前缀。
     * 将<your-object>替换为Object完整路径，例如exampleobject.txt。Object完整路径中不能包含Bucket名称。
     * 指定过期时间，单位为毫秒。
     */
    private static final String BUCKET_NAME = "<your-bucket>";
    private static final String OBJECT_NAME = "<your-object>";
    private static final long EXPIRE_TIME = 3600 * 1000L;

    @Autowired
    private OSS ossClient;

    @GetMapping("/get_presigned_url_for_oss_upload")
    @ResponseBody
    public String generatePresignedURL() {

        try {
            GeneratePresignedUrlRequest request = new GeneratePresignedUrlRequest(BUCKET_NAME, OBJECT_NAME, HttpMethod.PUT);
            Date expiration = new Date(System.currentTimeMillis() + EXPIRE_TIME);
            request.setExpiration(expiration);
            request.setContentType("image/png");
            URL signedUrl = ossClient.generatePresignedUrl(request);
            return signedUrl.toString();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}

Go

package main

import (
	"fmt"
	"net/http"
	"os"

	"github.com/aliyun/aliyun-oss-go-sdk/oss"
)

func getURL() string {
	// yourEndpoint填写Bucket对应的Endpoint，以华东1（杭州）为例，填写为https://oss-cn-hangzhou.aliyuncs.com。其它Region请按实际情况填写。
	endpoint := "https://oss-cn-beijing.aliyuncs.com"
	// 填写Bucket名称，例如examplebucket。
	bucketName := "examplebucket"
	// 填写文件完整路径，例如exampledir/exampleobject.txt。文件完整路径中不能包含Bucket名称。
	objectName := "exampledir/exampleobject.txt"
	// 从环境变量中获取访问凭证。运行本示例代码之前，请确保已设置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID和ALIBABA_CLOUD_ACCESS_KEY_SECRET。
	accessKeyID := os.Getenv("ALIBABA_CLOUD_ACCESS_KEY_ID")
	accessKeySecret := os.Getenv("ALIBABA_CLOUD_ACCESS_KEY_SECRET")

	client, err := oss.New(endpoint, accessKeyID, accessKeySecret)
	if err != nil {
		fmt.Println("json err:", err)
	}
	bucket, err := client.Bucket(bucketName)
	if err != nil {
		fmt.Println("json err:", err)
	}
	options := []oss.Option{
		oss.ContentType("image/png"),
	}
	signedURL, err := bucket.SignURL(objectName, oss.HTTPPut, 60, options...)
	if err != nil {
		fmt.Println("json err:", err)
	}

	return signedURL
}

func handler(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path == "/" {
		http.ServeFile(w, r, "templates/index.html")
		return
	} else if r.URL.Path == "/get_presigned_url_for_oss_upload" {
		url := getURL()
		fmt.Fprintf(w, "%s", url)
		return
	}
	http.NotFound(w, r)
}
func main() {
	http.HandleFunc("/", handler)
	http.ListenAndServe(":8080", nil)
}

PHP

<?php
require_once __DIR__ . '/vendor/autoload.php';
use OSS\OssClient;
use OSS\Core\OssException;
use OSS\Http\RequestCore;
use OSS\Http\ResponseCore;
// 运行本示例代码之前，请确保已设置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID和ALIBABA_CLOUD_ACCESS_KEY_SECRET。
$accessKeyId = getenv("ALIBABA_CLOUD_ACCESS_KEY_ID");
$accessKeySecret = getenv("ALIBABA_CLOUD_ACCESS_KEY_SECRET");
// yourEndpoint填写Bucket所在地域对应的Endpoint。以华东1（杭州）为例，Endpoint填写为https://oss-cn-hangzhou.aliyuncs.com。
$endpoint = "<YOUR-ENDPOINT>";
// 填写Bucket名称。
$bucket= "<YOUR-BUCKET>";
// 填写不包含Bucket名称在内的Object完整路径。
$object = "test.png";
// 设置签名URL的有效时长为3600秒。
$timeout = 3600;
try {
    $ossClient = new OssClient($accessKeyId, $accessKeySecret, $endpoint, false);
    // 生成签名URL。
    $signedUrl = $ossClient->signUrl($bucket, $object, $timeout, "PUT", array('Content-Type' => 'image/png'));
    // 打印返回的数据
    echo $signedUrl;
} catch (OssException $e) {
    printf($e->getMessage() . "\n");
    return;
}

Node.js

const express = require("express");
const { Buffer } = require("buffer");
const OSS = require("ali-oss");
const app = express();
const path = require("path");
const fs = require("fs");
const axios = require("axios");

const config = {
  // <YOURREGION>填写Bucket所在地域。以华东1（杭州）为例，Region填写为oss-cn-hangzhou。
  region: '<YOURREGION>',
  // 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID。
  accessKeyId: process.env.ALIBABA_CLOUD_ACCESS_KEY_ID,
  // 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_SECRET。
  accessKeySecret: process.env.ALIBABA_CLOUD_ACCESS_KEY_SECRET,
  // 将<YOUR-BUCKET>替换为Bucket名称。
  bucket: "<YOUR-BUCKET>",
}
const object = "examplefile.png";

app.use(express.static(path.join(__dirname, "templates")));

app.get("/get_presigned_url_for_oss_upload", async (req, res) => {
    const client = new OSS(config);
    const url = client.signatureUrl(object, {
        method: "PUT",
        "Content-Type": "application/x-www-form-urlencoded",
    });
    res.send(url); 
    console.log(url);
  });

app.listen(8000, () => {
  console.log("http://127.0.0.1:8000");
});

Ruby

require 'sinatra'
require 'base64'
require 'open-uri'
require 'cgi'
require 'openssl'
require 'json'
require 'sinatra/reloader'
require 'sinatra/content_for'
require 'aliyun/oss'
include Aliyun::OSS

# 设置public文件夹路径为当前文件夹下的templates文件夹
set :public_folder, File.dirname(__FILE__) + '/templates'

# 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID。
$access_key_id = ENV['ALIBABA_CLOUD_ACCESS_KEY_ID']
# 配置环境变量ALIBABA_CLOUD_ACCESS_SECRET。
$access_key_secret = ENV['ALIBABA_CLOUD_ACCESS_KEY_SECRET']

# 填写Object完整路径，例如exampledir/exampleobject.png。Object完整路径中不能包含Bucket名称。
object_key = 'exampledir/exampleobject.png'

def get_presigned_url(client, object_key)
  # 将<YOUR-BUCKET>替换为Bucket名称。
  bucket = client.get_bucket('<YOUR-BUCKET>')
  # 生成签名URL，并指定URL有效时间为1小时（3600秒）。
  bucket.object_url(object_key, 3600)
end

client = Aliyun::OSS::Client.new(
  # 将<YOUR-ENDPOINT>替换为Bucket所在地域对应的Endpoint。以华东1（杭州）为例，Endpoint填写为https://oss-cn-hangzhou.aliyuncs.com。
  endpoint: '<YOUR-ENDPOINT>',
  # 从环境变量中获取访问凭证。运行本示例代码之前，请确保已设置环境变量OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
  access_key_id: $access_key_id,
  access_key_secret: $access_key_secret
)


if ARGV.length == 1 
  $server_port = ARGV[0]
elsif ARGV.length == 2
  $server_ip = ARGV[0]
  $server_port = ARGV[1]
end

$server_ip = "0.0.0.0"
$server_port = 8000

puts "App server is running on: http://#{$server_ip}:#{$server_port}"

set :bind, $server_ip
set :port, $server_port

get '/get_presigned_url_for_oss_upload' do
  url = get_presigned_url(client, object_key.to_s)
  puts "Token: #{url}"
  url
end

get '/*' do
  puts "********************* GET "
  send_file File.join(settings.public_folder, 'index.html')
end

C#

using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.AspNetCore.Http;
using System.IO;
using System;
using Microsoft.Extensions.Logging;
using Aliyun.OSS;

namespace YourNamespace
{
    public class Program
    {
        private ILogger<Program> _logger;

        // 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID。
        public string AccessKeyId { get; set; } = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID");
        // 配置环境变量ALIBABA_CLOUD_ACCESS_KEY_SECRET。
        public string AccessKeySecret { get; set; } = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET");
        // <YOUR-ENDPOINT>替换为Bucket所在地域对应的Endpoint。以华东1（杭州）为例，Endpoint填写为https://oss-cn-hangzhou.aliyuncs.com。
        private string EndPoint { get; set; } = "<YOUR-ENDPOINT>";
        // 将<YOUR-BUCKET>替换为Bucket名称。
        private string BucketName { get; set; } = "<YOUR-BUCKET>";
        private string ObjectName { get; set; } = "exampledir/exampleobject2.png";

        public static void Main(string[] args)
        {
            var builder = WebApplication.CreateBuilder(args);
            var app = builder.Build();

            // 添加日志
            builder.Logging.AddConsole();
            var logger = builder.Services.BuildServiceProvider().GetRequiredService<ILogger<Program>>();

            app.UseStaticFiles(); // 添加这行以启用静态文件中间件

            app.MapGet("/", async (context) =>
            {
                var filePath = Path.Combine(Directory.GetCurrentDirectory(), "templates/index.html");
                var htmlContent = await File.ReadAllTextAsync(filePath);
                await context.Response.WriteAsync(htmlContent);

                // 打印日志
                logger.LogInformation("GET request to root path");
            });

            app.MapGet("/get_presigned_url_for_oss_upload", async (context) =>
            {
                var program = new Program(logger);
                var signedUrl = program.GetSignedUrl();

                logger.LogInformation($"SignedUrl: {signedUrl}"); // 打印token的值
                await context.Response.WriteAsync(signedUrl);
            });

            app.Run();
        }

        // 构造函数注入ILogger
        public Program(ILogger<Program> logger)
        {
            _logger = logger;
        }

        private string GetSignedUrl()
        {
            // 创建OSSClient实例
            var ossClient = new OssClient(EndPoint, AccessKeyId, AccessKeySecret);

            // 生成签名URL
            var generatePresignedUriRequest = new GeneratePresignedUriRequest(BucketName, ObjectName, SignHttpMethod.Put)
            {
                Expiration = DateTime.Now.AddHours(1),
                ContentType = "image/png"
            };
            var signedUrl = ossClient.GeneratePresignedUri(generatePresignedUriRequest);

            return signedUrl.ToString();
        }
    }
}

客户端示例代码

Web端使用签名URL上传文件到OSS的示例代码如下：

JavaScript

const form = document.querySelector("form");
form.addEventListener("submit", (event) => {
  event.preventDefault();
  const fileInput = document.querySelector("#file");
  const file = fileInput.files[0];
  fetch("/get_presigned_url_for_oss_upload", { method: "GET" })
    .then((response) => {
      if (!response.ok) {
        throw new Error("获取预签名URL失败");
      }
      return response.text();
    })
    .then((url) => {
      fetch(url, {
        method: "PUT",
        headers: new Headers({
          "Content-Type": "image/png",
        }),
        body: file,
      }).then((response) => {
        if (!response.ok) {
          throw new Error("文件上传到OSS失败");
        }
        console.log(response);
        alert("文件已上传");
      });
    })
    .catch((error) => {
      console.error("发生错误:", error);
      alert(error.message);
    });
});

客户端自行拦截

对于需要限制上传文件属性的场景，您可以在客户端上通过JavaScript代码来实现。通过条件语句检查文件大小和文件类型是否满足要求，如果不满足，则弹出警告或错误信息，阻止上传操作。需要注意的是，STS临时访问凭证不支持设置限制上传文件的大小及类型。因此，如果STS临时访问凭证被截取，恶意用户可能会绕过客户端限制，直接上传恶意文件到您的OSS。

示例代码

客户端示例代码

使用<input type="file">元素的files属性和accept属性来检查文件大小和文件类型是否符合要求的示例代码如下：

<!DOCTYPE html>
<html>
<head>
  <title>文件上传</title>
  <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
</head>
<body>
  <input type="file" id="file-upload" accept="image/jpeg, image/png, application/pdf" />
  <button onclick="uploadFile()">上传</button>

  <script>
    function uploadFile() {
      const fileInput = document.getElementById('file-upload');
      const file = fileInput.files[0];

      // 文件大小限制（单位：字节）
      const maxFileSize = 1024 * 1024; // 1MB

      // 允许的文件类型
      const allowedTypes = ['image/jpeg', 'image/png', 'application/pdf'];

      if (file) {
        // 检查文件大小
        if (file.size > maxFileSize) {
          alert('文件大小超过限制。请上传小于1MB的文件。');
          return;
        }

        // 检查文件类型
        if (!allowedTypes.includes(file.type)) {
          alert('不支持的文件类型。请上传JPEG、PNG或PDF文件。');
          return;
        }

        // 文件验证通过，可以进行上传操作
        // 这里可以编写具体的上传逻辑
        console.log('开始上传文件:', file.name);
        // 上传的代码
      } else {
        alert('请选择要上传的文件。');
      }
    }
  </script>
</body>
</html>