本文介绍如何解冻归档文件。

解冻归档文件的完整代码请参见GitHub。

归档类型（Archive）的文件需要解冻（Restore）之后才能读取。非归档类型的文件，不要调用RestoreObject方法。

归档类型的Object在执行解冻前后的状态变换过程如下：
  1. 归档类型的Object初始时处于冷冻状态。
  2. 提交一次解冻请求后，Object处于解冻中的状态。完成解冻任务通常需要1分钟，最长等待任务完成时间为4小时。
  3. 服务端完成解冻任务后，Object进入解冻状态，此时您可以读取Object。解冻状态默认持续24小时，24小时内再次调用RestoreObject接口则解冻状态会自动延长24小时。对于同份归档文件，一次解冻流程内可有效调用7次RestoreObject接口达到最长7天的解冻持续时间。
  4. 解冻状态结束后，Object再次返回到冷冻状态。

以下代码用于解冻归档文件：

using Aliyun.OSS;
using Aliyun.OSS.Model;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
var objectName = "<yourObjectName>";
var objectContent = "More than just cloud.";
int maxWaitTimeInSeconds = 600;
// 创建OssClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    // 创建归档存储空间。
    var bucket = client.CreateBucket(bucketName, StorageClass.Archive);
    Console.WriteLine("Create Archive bucket succeeded, {0} ", bucket.Name);
}
catch (Exception ex)
{
    Console.WriteLine("Create Archive bucket failed, {0}", ex.Message);
}
// 上传文件。
try
{
    byte[] binaryData = Encoding.ASCII.GetBytes(objectContent);
    MemoryStream requestContent = new MemoryStream(binaryData);
    client.PutObject(bucketName, objectName, requestContent);
    Console.WriteLine("Put object succeeded, {0}", objectName);
}
catch (Exception ex)
{
    Console.WriteLine("Put object failed, {0}", ex.Message);
}
var metadata = client.GetObjectMetadata(bucketName, objectName);
string storageClass = metadata.HttpMetadata["x-oss-storage-class"] as string;
if (storageClass != "Archive")
{
    Console.WriteLine("StorageClass is {0}", storageClass);
    return;
}
// 解冻文件。
RestoreObjectResult result = client.RestoreObject(bucketName, objectName);
Console.WriteLine("RestoreObject result HttpStatusCode : {0}", result.HttpStatusCode);
if (result.HttpStatusCode != HttpStatusCode.Accepted)
{
    throw new OssException(result.RequestId + ", " + result.HttpStatusCode + " ,");
}
while (maxWaitTimeInSeconds > 0)
{
    var meta = client.GetObjectMetadata(bucketName, objectName);
    string restoreStatus = meta.HttpMetadata["x-oss-restore"] as string;
    if (restoreStatus != null && restoreStatus.StartsWith("ongoing-request=\"false\"", StringComparison.InvariantCultureIgnoreCase))
    {
        break;
    }
    Thread.Sleep(1000);
    maxWaitTimeInSeconds--;
}
if (maxWaitTimeInSeconds == 0)
{
    Console.WriteLine("RestoreObject is timeout. ");
    throw new TimeoutException();
}
else
{
    Console.WriteLine("RestoreObject is successful. ");
}

归档存储类型的详细说明请参见存储类型介绍。相关状态码的详细解释请参见API文档RestoreObject。