Object Storage Service:Baixe um objeto usando uma URL assinada (PHP SDK V2)

Observações

• O código de exemplo deste tópico usa o ID da região China (Hangzhou), cn-hangzhou, como referência. Por padrão, ele usa um endpoint público. Para acessar o OSS a partir de outros serviços da Alibaba Cloud na mesma região, use um endpoint interno. Para mais detalhes sobre as regiões e endpoints compatíveis com o OSS, consulte Regions and endpoints.

• Este tópico demonstra o uso de variáveis de ambiente para obter credenciais de acesso. Para ver outros exemplos de configuração de credenciais, consulte Configure access credentials for PHP.

• Não são necessárias permissões especiais para gerar uma URL assinada. No entanto, terceiros só conseguirão baixar o objeto com sucesso se você possuir a permissão oss:GetObject. Para saber mais sobre como conceder permissões, consulte Grant custom access policies to a RAM user.

• Os exemplos de código apresentados aqui usam uma URL assinada V4, cuja validade máxima é de 7 dias. Para mais informações, consulte Signature V4 (recommended).

Procedimento

O procedimento a seguir descreve como baixe um objeto usando uma URL pré-assinada:

Parâmetros

Código de exemplo

1. O proprietário do objeto gera uma URL assinada para uma solicitação GET.

   <?php
   
   // Import the autoloader file to ensure that dependency libraries are loaded correctly.
   require_once __DIR__ . '/../../vendor/autoload.php';
   
   use AlibabaCloud\Oss\V2 as Oss;
   
   // Define the description for command-line arguments.
   $optsdesc = [
       "region" => ['help' => 'The region in which the bucket is located.', 'required' => True], // The region where the bucket is located. (Required)
       "endpoint" => ['help' => 'The domain names that other services can use to access OSS.', 'required' => False], // The endpoint to access OSS. (Optional)
       "bucket" => ['help' => 'The name of the bucket', 'required' => True], // The bucket name. (Required)
       "key" => ['help' => 'The name of the object', 'required' => True], // The object name. (Required)
       "expire" => ['help' => 'The expiration time in seconds (default: 900)', 'required' => False], // The expiration time in seconds. (Optional, default: 900)
   ];
   
   // Convert the argument descriptions to the long options format required by getopt.
   // A colon ":" after each argument indicates that it requires a value.
   $longopts = \array_map(function ($key) {
       return "$key:";
   }, array_keys($optsdesc));
   
   // Parse the command-line arguments.
   $options = getopt("", $longopts);
   
   // Check if all required arguments are provided.
   foreach ($optsdesc as $key => $value) {
       if ($value['required'] === True && empty($options[$key])) {
           $help = $value['help']; // Get the help information for the argument.
           echo "Error: the following arguments are required: --$key, $help" . PHP_EOL;
           exit(1); // If a required argument is missing, exit the program.
       }
   }
   
   // Extract values from the parsed arguments.
   $region = $options["region"]; // The region where the bucket is located.
   $bucket = $options["bucket"]; // The bucket name.
   $key = $options["key"];       // The object name.
   $expire = isset($options["expire"]) ? (int)$options["expire"] : 900; // The expiration time. Default: 900 seconds.
   
   // Load the credentials from environment variables.
   // Use EnvironmentVariableCredentialsProvider to read the Access Key ID and Access Key Secret from environment variables.
   $credentialsProvider = new Oss\Credentials\EnvironmentVariableCredentialsProvider();
   
   // Use the default configurations of the SDK.
   $cfg = Oss\Config::loadDefault();
   $cfg->setCredentialsProvider($credentialsProvider); // Set the credential provider.
   $cfg->setRegion($region); // Set the region where the bucket is located.
   if (isset($options["endpoint"])) {
       $cfg->setEndpoint($options["endpoint"]); // If an endpoint is provided, set it.
   }
   
   try {
       // Create an OSS client instance.
       $client = new Oss\Client($cfg);
   
       // Create a GetObjectRequest object to download the object.
       $request = new Oss\Models\GetObjectRequest(bucket:$bucket, key:$key);
   
       // Call the presign method to generate a signed URL and set the expiration time.
       $result = $client->presign($request, [
           'expires' => new \DateInterval("PT{$expire}S") // PT stands for Period Time, and S stands for seconds.
       ]);
   
       // Output the signed URL.
       echo "Signed URL: " . $result->url . PHP_EOL;
   } catch (Exception $e) {
       echo "Error: " . $e->getMessage() . PHP_EOL;
       exit(1);
   }

2. Outros usuários baixam o objeto usando a URL assinada para a solicitação GET.

   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******************************************************"

   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) {
           // Replace with the generated presigned URL for the GET request.
           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******************************************************";
           // Enter the destination path to save the file, including the file name and extension.
           String savePath = "C:/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");
   
           // Check the response code.
           int responseCode = httpConn.getResponseCode();
           if (responseCode == HttpURLConnection.HTTP_OK) {
               // Input stream.
               InputStream inputStream = new BufferedInputStream(httpConn.getInputStream());
               // Output stream.
               FileOutputStream outputStream = new FileOutputStream(savePath);
   
               byte[] buffer = new byte[4096]; // Buffer.
               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 = "C:/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. Server responded with code: ${response.statusCode}`);
       }
   }).on('error', (err) => {
       console.error("Error during download:", err.message);
   });

   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 = "C:/downloads/myfile.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"No file to download. Server replied HTTP code: {response.status_code}")
   except Exception as e:
       print("Error during download:", e)

   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 := "C:/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

   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 = "C:/downloads/myfile.txt"; // The file name to use for the download.
   
   fetch(fileURL)
       .then(response => {
           if (!response.ok) {
               throw new Error(`Server replied HTTP code: ${response.status}`);
           }
           return response.blob(); // Convert the response to a blob.
       })
       .then(blob => {
           const link = document.createElement('a');
           link.href = window.URL.createObjectURL(blob);
           link.download = savePath; // Set the name of the downloaded file.
           document.body.appendChild(link); // This step ensures that the link exists in the document.
           link.click(); // Simulate a click on the download link.
           link.remove(); // Remove the link after completion.
           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"; // The modified save path.
           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 {
           // Define the file URL and save path (change to a valid path).
           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"; // Replace with your username.
           
           // Create a URL object.
           NSURL *url = [NSURL URLWithString:fileURL];
           
           // Create a download task.
           NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
               // Error handling.
               if (error) {
                   NSLog(@"Error during download: %@", error.localizedDescription);
                   return;
               }
               
               // Check the data.
               if (!data) {
                   NSLog(@"No data received.");
                   return;
               }
               
               // Save the file.
               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);
               }
           }];
           
           // Start the task.
           [task resume];
           
           // Keep the main thread running so that the asynchronous request can be completed.
           [[NSRunLoop currentRunLoop] run];
       }
       return 0;
   }

Cenários comuns

<?php

// Import the autoloader file to ensure that dependency libraries are loaded correctly.
require_once __DIR__ . '/../vendor/autoload.php';

use AlibabaCloud\Oss\V2 as Oss;

// Define the description for command-line arguments.
$optsdesc = [
    "region" => ['help' => 'The region in which the bucket is located.', 'required' => True], // The region where the bucket is located. (Required)
    "endpoint" => ['help' => 'The domain names that other services can use to access OSS.', 'required' => False], // The endpoint to access OSS. (Optional)
    "bucket" => ['help' => 'The name of the bucket', 'required' => True], // The bucket name. (Required)
    "key" => ['help' => 'The name of the object', 'required' => True], // The object name. (Required)
];

// Convert the argument descriptions to the long options format required by getopt.
// A colon ":" after each argument indicates that it requires a value.
$longopts = \array_map(function ($key) {
    return "$key:";
}, array_keys($optsdesc));

// Parse the command-line arguments.
$options = getopt("", $longopts);

// Check if all required arguments are provided.
foreach ($optsdesc as $key => $value) {
    if ($value['required'] === True && empty($options[$key])) {
        $help = $value['help']; // Get the help information for the argument.
        echo "Error: the following arguments are required: --$key, $help" . PHP_EOL;
        exit(1); // If a required argument is missing, exit the program.
    }
}

// Extract values from the parsed arguments.
$region = $options["region"]; // The region where the bucket is located.
$bucket = $options["bucket"]; // The bucket name.
$key = $options["key"];       // The object name.

// Load the credentials from environment variables.
// Use EnvironmentVariableCredentialsProvider to read the Access Key ID and Access Key Secret from environment variables.
$credentialsProvider = new Oss\Credentials\EnvironmentVariableCredentialsProvider();

// Use the default configurations of the SDK.
$cfg = Oss\Config::loadDefault();
$cfg->setCredentialsProvider($credentialsProvider); // Set the credential provider.
$cfg->setRegion($region); // Set the region where the bucket is located.
if (isset($options["endpoint"])) {
    $cfg->setEndpoint($options["endpoint"]); // If an endpoint is provided, set it.
}

// Create an OSS client instance.
$client = new Oss\Client($cfg);

$versionId = "yourVersionId"; // The version number. This is an example value. Replace it with a real version ID.

// Create a GetObjectRequest object to download the object.
$request = new Oss\Models\GetObjectRequest(bucket:$bucket, key:$key, versionId: $versionId);

// Call the presign method to generate a signed URL.
$result = $client->presign($request);

// Print the presign result.
// Output the signed URL, which users can use directly to download the object.
print(
    'get object presign result:' . var_export($result, true) . PHP_EOL . // Detailed information about the presign result.
    'get object url:' . $result->url . PHP_EOL                           // The signed URL for directly downloading the object.
);

<?php

// Import the autoloader file to ensure that dependency libraries are loaded correctly.
require_once __DIR__ . '/../vendor/autoload.php';

use AlibabaCloud\Oss\V2 as Oss;

// Define the description for command-line arguments.
$optsdesc = [
    "region" => ['help' => 'The region in which the bucket is located.', 'required' => True], // The region where the bucket is located. (Required)
    "endpoint" => ['help' => 'The domain names that other services can use to access OSS.', 'required' => False], // The endpoint to access OSS. (Optional)
    "bucket" => ['help' => 'The name of the bucket', 'required' => True], // The bucket name. (Required)
    "key" => ['help' => 'The name of the object', 'required' => True], // The object name. (Required)
];

// Convert the argument descriptions to the long options format required by getopt.
// A colon ":" after each argument indicates that it requires a value.
$longopts = \array_map(function ($key) {
    return "$key:";
}, array_keys($optsdesc));

// Parse the command-line arguments.
$options = getopt("", $longopts);

// Check if all required arguments are provided.
foreach ($optsdesc as $key => $value) {
    if ($value['required'] === True && empty($options[$key])) {
        $help = $value['help']; // Get the help information for the argument.
        echo "Error: the following arguments are required: --$key, $help" . PHP_EOL;
        exit(1); // If a required argument is missing, exit the program.
    }
}

// Extract values from the parsed arguments.
$region = $options["region"]; // The region where the bucket is located.
$bucket = $options["bucket"]; // The bucket name.
$key = $options["key"];       // The object name.

// Load the credentials from environment variables.
// Use EnvironmentVariableCredentialsProvider to read the Access Key ID and Access Key Secret from environment variables.
$credentialsProvider = new Oss\Credentials\EnvironmentVariableCredentialsProvider();

// Use the default configurations of the SDK.
$cfg = Oss\Config::loadDefault();
$cfg->setCredentialsProvider($credentialsProvider); // Set the credential provider.
$cfg->setRegion($region); // Set the region where the bucket is located.
$cfg->setEndpoint(endpoint: "http://static.example.com"); // Set this to your custom endpoint.
$cfg->setUseCname(true); // Set to use a CNAME.

// Create an OSS client instance.
$client = new Oss\Client($cfg);

// Create a GetObjectRequest object to download the object.
$request = new Oss\Models\GetObjectRequest(bucket:$bucket, key:$key);

// Call the presign method to generate a signed URL.
$result = $client->presign($request);

// Print the presign result.
// Output the signed URL, which users can use directly to download the object.
print(
    'get object presign result:' . var_export($result, true) . PHP_EOL . // Detailed information about the presign result.
    'get object url:' . $result->url . PHP_EOL                           // The signed URL for directly downloading the object.
);

Referências

• Para acessar o código de exemplo completo sobre geração de URLs assinadas, consulte o exemplo no GitHub.

• Para obter mais detalhes sobre a operação de API Presign, consulte Presign.