Object Storage Service:Download a file (C# SDK V1)

Ao chamar a operação GetObject em um bucket, uma das seguintes situações se aplica:

• Se a versão atual do objeto for um marcador de exclusão, o OSS retorna 404 Not Found.

• Caso você especifique o versionId de um objeto no parâmetro de consulta, a versão especificada será retornada. Se definir o versionId como "null", o sistema retorna a versão do objeto que possui um versionId nulo.

• Ao tentar recuperar um marcador de exclusão especificando seu versionId, o OSS retorna 405 Method Not Allowed.

using System;
using System.IO;
using Aliyun.OSS;
using Aliyun.OSS.Common;

namespace Samples
{
    public class Program
    {
        public static void Main(string[] args)
        {
            // Set yourEndpoint to the Endpoint of the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com.
            var endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
            // Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set.
            var accessKeyId = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_ID");
            var accessKeySecret = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_SECRET");
            // Specify the bucket name. Example: examplebucket.
            var bucketName = "examplebucket";
            // Specify the full path of the object. The full path cannot contain the bucket name. Example: exampledir/exampleobject.txt.
            var objectName = "exampledir/exampleobject.txt";
            // Specify the full path of the local file. Example: D:\\localpath\\examplefile.txt.
            var downloadFilename = "D:\\localpath\\examplefile.txt";
            var versionid = "yourArchiveObjectVersionid";
            // Specify the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the region to cn-hangzhou.
            const string region = "cn-hangzhou";
            
            // Create a ClientConfiguration instance and modify the default parameters as needed.
            var conf = new ClientConfiguration();
            
            // Set the signature version to V4.
            conf.SignatureVersion = SignatureVersion.V4;
            
            // Create an OssClient instance.
            var client = new OssClient(endpoint, accessKeyId, accessKeySecret, conf);
            client.SetRegion(region);
            try
            {
                // Download the file to a stream. OssObject contains various information about the file, such as the bucket where the file is stored, the file name, metadata, and an input stream.
                var request = new GetObjectRequest(bucketName, objectName)
                {
                    // Specify the version ID of the object.
                    VersionId = versionid
                };
                var obj = client.GetObject(request);
                using (var requestStream = obj.Content)
                {
                    byte[] buf = new byte[1024];
                    var fs = File.Open(downloadFilename, FileMode.OpenOrCreate);
                    var len = 0;
                    // Read the content of the file to a file or memory using the input stream.
                    while ((len = requestStream.Read(buf, 0, 1024)) != 0)
                    {
                        fs.Write(buf, 0, len);
                    }
                    fs.Close();
                }
                Console.WriteLine("Get object succeeded, vesionid:{0}", versionid);
            }
            catch (Exception ex)
            {
                Console.WriteLine("Get object failed. {0}", ex.Message);
            }
        }
    }
}