Overview

This document provides an overview of APIs and SDK sample codes related to object download.

SDK API Reference

For the parameters and method descriptions of all the APIs in the SDK, see Api Documentation.

Advanced APIs (recommended)

Downloading an object

Sample 1. Downloading an object

// Initialize TransferConfig
TransferConfig transferConfig = new TransferConfig();

// Initialize TransferManager
TransferManager transferManager = new TransferManager(cosXml, transferConfig);

String bucket = "examplebucket-1250000000"; // Bucket name in the format: BucketName-APPID
String cosPath = "exampleobject"; // The location identifier of the object in the bucket, i.e. the object key
string localDir = System.IO.Path.GetTempPath();// Local file directory
string localFileName = "my-local-temp-file"; // Specify the name of the file to be saved locally

// Download an object
COSXMLDownloadTask downloadTask = new COSXMLDownloadTask(bucket, cosPath, 
  localDir, localFileName);

downloadTask.progressCallback = delegate (long completed, long total)
{
    Console.WriteLine(String.Format("progress = {0:##.##}%", completed * 100.0 / total));
};

try {
  COSXML.Transfer.COSXMLDownloadTask.DownloadTaskResult result = await 
    transferManager.DownloadAsync(downloadTask);
  Console.WriteLine(result.GetResultInfo());
  string eTag = result.eTag;
} catch (Exception e) {
    Console.WriteLine("CosException: " + e);
}

Note：

For the complete sample, go to GitHub.

Sample 2. Downloading multiple objects

TransferConfig transferConfig = new TransferConfig();

// Initialize TransferManager
TransferManager transferManager = new TransferManager(cosXml, transferConfig);

string bucket = "examplebucket-1250000000"; // Bucket name in the format: BucketName-APPID
string localDir = System.IO.Path.GetTempPath();// Local file directory

for (int i = 0; i < 5; i++) {
  // Download a set of objects
  string cosPath = "exampleobject" + i; // The location identifier of an object in the bucket, i.e. the object key
  string localFileName = "my-local-temp-file"; // Specify the name of the file to be saved locally
  COSXMLDownloadTask downloadTask = new COSXMLDownloadTask(bucket, cosPath, 
    localDir, localFileName);
  await transferManager.DownloadAsync(downloadTask);
}

Note：

For the complete sample, go to GitHub.

Simple Operations

Downloading an object

API description

This API is used to download an object to the local file system.

Sample code

try
{
  string bucket = "examplebucket-1250000000"; // Bucket name in the format: BucketName-APPID
  string key = "exampleobject"; // Object key
  string localDir = System.IO.Path.GetTempPath();// Local file directory
  string localFileName = "my-local-temp-file"; // Specify the name of the file to be saved locally
  GetObjectRequest request = new GetObjectRequest(bucket, key, localDir, localFileName);
  // Set progress callback
  request.SetCosProgressCallback(delegate (long completed, long total)
  {
    Console.WriteLine(String.Format("progress = {0:##.##}%", completed * 100.0 / total));
  });
  // Execute the request
  GetObjectResult result = cosXml.GetObject(request);
  // Request succeeded
  Console.WriteLine(result.GetResultInfo());
}
catch (COSXML.CosException.CosClientException clientEx)
{
  // Request failed
  Console.WriteLine("CosClientException: " + clientEx);
}
catch (COSXML.CosException.CosServerException serverEx)
{
  // Request failed
  Console.WriteLine("CosServerException: " + serverEx.GetInfo());
}

Note：

For the complete sample, go to GitHub.