Object Storage Service:Download an object using a presigned URL

curl

curl -SO "https://examplebucket.oss-cn-hangzhou.aliyuncs.com/exampleobject.txt?x-oss-date=20241112T092756Z&x-oss-expires=3599&x-oss-signature-version=OSS4-HMAC-SHA256&x-oss-credential=LTAI****************/20241112/cn-hangzhou/oss/aliyun_v4_request&x-oss-signature=ed5a******************************************************"

Python

import requests

file_url = "https://examplebucket.oss-cn-hangzhou.aliyuncs.com/exampleobject.txt?x-oss-date=20241112T092756Z&x-oss-expires=3599&x-oss-signature-version=OSS4-HMAC-SHA256&x-oss-credential=LTAI****************/20241112/cn-hangzhou/oss/aliyun_v4_request&x-oss-signature=ed5a******************************************************"
save_path = "/downloads/exampleobject.txt"

try:
    response = requests.get(file_url, stream=True)
    if response.status_code == 200:
        with open(save_path, 'wb') as f:
            for chunk in response.iter_content(4096):
                f.write(chunk)
        print("Download completed!")
    else:
        print(f"Download failed. Status code: {response.status_code}")
except Exception as e:
    print("Error during download:", e)

Java

import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class Demo {
    public static void main(String[] args) {
        String fileURL = "https://examplebucket.oss-cn-hangzhou.aliyuncs.com/exampleobject.txt?x-oss-date=20241112T092756Z&x-oss-expires=3599&x-oss-signature-version=OSS4-HMAC-SHA256&x-oss-credential=LTAI****************/20241112/cn-hangzhou/oss/aliyun_v4_request&x-oss-signature=ed5a******************************************************";
        String savePath = "/downloads/myfile.txt";

        try {
            downloadFile(fileURL, savePath);
            System.out.println("Download completed!");
        } catch (IOException e) {
            System.err.println("Error during download: " + e.getMessage());
        }
    }

    private static void downloadFile(String fileURL, String savePath) throws IOException {
        URL url = new URL(fileURL);
        HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setRequestMethod("GET");

        int responseCode = httpConn.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            InputStream inputStream = new BufferedInputStream(httpConn.getInputStream());
            FileOutputStream outputStream = new FileOutputStream(savePath);

            byte[] buffer = new byte[4096];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }

            outputStream.close();
            inputStream.close();
        } else {
            System.out.println("No file to download. Server replied HTTP code: " + responseCode);
        }
        httpConn.disconnect();
    }
}

Node.js

const https = require('https');
const fs = require('fs');

const fileURL = "https://examplebucket.oss-cn-hangzhou.aliyuncs.com/exampleobject.txt?x-oss-date=20241112T092756Z&x-oss-expires=3599&x-oss-signature-version=OSS4-HMAC-SHA256&x-oss-credential=LTAI****************/20241112/cn-hangzhou/oss/aliyun_v4_request&x-oss-signature=ed5a******************************************************";
const savePath = "/downloads/myfile.txt";

https.get(fileURL, (response) => {
    if (response.statusCode === 200) {
        const fileStream = fs.createWriteStream(savePath);
        response.pipe(fileStream);

        fileStream.on('finish', () => {
            fileStream.close();
            console.log("Download completed!");
        });
    } else {
        console.error(`Download failed. Status code: ${response.statusCode}`);
    }
}).on('error', (err) => {
    console.error("Error during download:", err.message);
});

Go

package main

import (
    "io"
    "net/http"
    "os"
)

func main() {
    fileURL := "https://examplebucket.oss-cn-hangzhou.aliyuncs.com/exampleobject.txt?x-oss-date=20241112T092756Z&x-oss-expires=3599&x-oss-signature-version=OSS4-HMAC-SHA256&x-oss-credential=LTAI****************/20241112/cn-hangzhou/oss/aliyun_v4_request&x-oss-signature=ed5a******************************************************"
    savePath := "/downloads/myfile.txt"

    response, err := http.Get(fileURL)
    if err != nil {
        panic(err)
    }
    defer response.Body.Close()

    if response.StatusCode == http.StatusOK {
        outFile, err := os.Create(savePath)
        if err != nil {
            panic(err)
        }
        defer outFile.Close()

        _, err = io.Copy(outFile, response.Body)
        if err != nil {
            panic(err)
        }
        println("Download completed!")
    } else {
        println("No file to download. Server replied HTTP code:", response.StatusCode)
    }
}

JavaScript (browser)

const fileURL = "https://examplebucket.oss-cn-hangzhou.aliyuncs.com/exampleobject.txt?x-oss-date=20241112T092756Z&x-oss-expires=3599&x-oss-signature-version=OSS4-HMAC-SHA256&x-oss-credential=LTAI****************/20241112/cn-hangzhou/oss/aliyun_v4_request&x-oss-signature=ed5a******************************************************";
const fileName = "exampleobject.txt";

fetch(fileURL)
    .then(response => {
        if (!response.ok) {
            throw new Error(`Server replied HTTP code: ${response.status}`);
        }
        return response.blob();
    })
    .then(blob => {
        const link = document.createElement('a');
        link.href = window.URL.createObjectURL(blob);
        link.download = fileName;
        document.body.appendChild(link);
        link.click();
        link.remove();
        console.log("Download completed!");
    })
    .catch(error => {
        console.error("Error during download:", error);
    });

Android (Java)

import android.os.AsyncTask;
import android.os.Environment;
import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class DownloadTask extends AsyncTask<String, String, String> {
    @Override
    protected String doInBackground(String... params) {
        String fileURL = params[0];
        String savePath = Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_DOWNLOADS) + "/myfile.txt";
        try {
            URL url = new URL(fileURL);
            HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
            httpConn.setRequestMethod("GET");
            int responseCode = httpConn.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                InputStream inputStream = new BufferedInputStream(httpConn.getInputStream());
                FileOutputStream outputStream = new FileOutputStream(savePath);
                byte[] buffer = new byte[4096];
                int bytesRead;
                while ((bytesRead = inputStream.read(buffer)) != -1) {
                    outputStream.write(buffer, 0, bytesRead);
                }
                outputStream.close();
                inputStream.close();
                return "Download completed!";
            } else {
                return "No file to download. Server replied HTTP code: " + responseCode;
            }
        } catch (Exception e) {
            return "Error during download: " + e.getMessage();
        }
    }
}

Objective-C

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSString *fileURL = @"https://examplebucket.oss-cn-hangzhou.aliyuncs.com/exampleobject.txt?x-oss-date=20241112T092756Z&x-oss-expires=3599&x-oss-signature-version=OSS4-HMAC-SHA256&x-oss-credential=LTAI****************/20241112/cn-hangzhou/oss/aliyun_v4_request&x-oss-signature=ed5a******************************************************";
        NSString *savePath = @"/Users/your_username/Desktop/myfile.txt";

        NSURL *url = [NSURL URLWithString:fileURL];

        NSURLSessionDataTask *task = [[NSURLSession sharedSession]
            dataTaskWithURL:url
            completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                if (error) {
                    NSLog(@"Error during download: %@", error.localizedDescription);
                    return;
                }
                if (!data) {
                    NSLog(@"No data received.");
                    return;
                }
                NSError *writeError = nil;
                BOOL success = [data writeToURL:[NSURL fileURLWithPath:savePath]
                                        options:NSDataWritingAtomic
                                          error:&writeError];
                if (success) {
                    NSLog(@"Download completed!");
                } else {
                    NSLog(@"Error saving file: %@", writeError.localizedDescription);
                }
            }];

        [task resume];
        [[NSRunLoop currentRunLoop] run];
    }
    return 0;
}

Download a specific version of an object

To restrict access to a specific object version, pass the versionId in the headers when generating the presigned URL.

# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider

auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())
endpoint = "https://oss-cn-hangzhou.aliyuncs.com"
region = "cn-hangzhou"
bucket = oss2.Bucket(auth, endpoint, "yourBucketName", region=region)

object_name = 'exampledir/exampleobject.txt'

headers = dict()
headers["versionId"] = "CAEQARiBgID8rumR2hYiIGUyOTAyZGY2MzU5MjQ5ZjlhYzQzZjNlYTAyZDE3****"

url = bucket.sign_url('GET', object_name, 600, slash_safe=True, headers=headers)
print('Presigned URL:', url)

Use request headers in the presigned URL

If you include request headers (such as Content-Type) when generating the URL, the recipient must send the same headers in the GET request. Otherwise, OSS rejects the request with a signature error.

Step 1: Generate the URL with request headers.

# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider

auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())
endpoint = "https://oss-cn-hangzhou.aliyuncs.com"
region = "cn-hangzhou"
bucket = oss2.Bucket(auth, endpoint, "yourBucketName", region=region)

object_name = 'exampledir/exampleobject.txt'

headers = dict()
headers['Content-Type'] = 'text/plain; charset=utf8'

# Optional query parameters (uncomment as needed):
params = dict()
# Bandwidth throttling in bit/s (example: 100 KB/s = 100 * 1024 * 8)
# params['x-oss-traffic-limit'] = str(100 * 1024 * 8)
# Restrict access to a specific IP address or CIDR block
# params['x-oss-ac-source-ip'] = "127.0.0.1"
# params['x-oss-ac-subnet-mask'] = "32"
# Restrict access to a specific VPC
# params['x-oss-ac-vpc-id'] = "vpc-t4nlw426y44rd3iq4xxxx"
# Allow or disallow request forwarding
# params['x-oss-ac-forward-allow'] = "true"

url = bucket.sign_url('GET', object_name, 600, slash_safe=True, headers=headers, params=params)
print('Presigned URL:', url)

Step 2: Download using the URL, passing the same headers.

curl:

curl -X GET "https://examplebucket.oss-cn-hangzhou.aliyuncs.com/exampleobject.txt?x-oss-date=20241113T093321Z&x-oss-expires=3599&x-oss-signature-version=OSS4-HMAC-SHA256&x-oss-credential=LTAI****************&x-oss-signature=ed5a******************************************************" \
  -H "Content-Type: text/plain; charset=utf8" \
  -o "myfile.txt"

Python:

import requests

def download_file(signed_url, file_path, headers=None):
    """
    Downloads an object using a presigned URL.

    :param signed_url: The presigned URL.
    :param file_path: Local path to save the downloaded object.
    :param headers: HTTP headers that were included when generating the URL.
    """
    if not headers:
        headers = {}

    try:
        response = requests.get(signed_url, headers=headers, stream=True)
        print(f"Status code: {response.status_code}")

        if response.status_code == 200:
            with open(file_path, 'wb') as file:
                for chunk in response.iter_content(chunk_size=8192):
                    if chunk:
                        file.write(chunk)
            print("Download completed!")
        else:
            print("Download failed.")
            print(response.text)
    except Exception as e:
        print(f"Error: {e}")

if __name__ == "__main__":
    signed_url = "<signedUrl>"
    file_path = "/downloads/exampleobject.txt"

    headers = {
        "Content-Type": "text/plain; charset=utf-8",
    }

    download_file(signed_url, file_path, headers=headers)

Generate a presigned URL using a custom domain name

To generate the URL using a custom domain name bound to your bucket, set is_cname=True and pass the custom domain as the endpoint.

# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider

auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())
region = "cn-hangzhou"

# Set the custom domain name as the endpoint.
endpoint = 'http://static.example.com'

bucket = oss2.Bucket(auth, endpoint, "yourBucketName", region=region, is_cname=True)

object_name = 'exampledir/exampleobject.txt'

url = bucket.sign_url('GET', object_name, 600, slash_safe=True)
print('Presigned URL:', url)