.NET SDK 手册

文件下载

NOS C# SDK 提供了丰富的文件下载接口，用户可以通过以下方式从 NOS 获取文件:

1. 下载文件到内存
2. 下载到本地文件
3. 分段下载
4. 条件下载

下载文件到内存

以下源代码实现下载文件到内存中:

// 初始化 NosClient
var nosClient = new NosClient(endpoint, accessKeyId, accessKeySecret);

/// <summary>
/// 下载文件到内存
/// </summary>
/// <param name="bucket">桶名</param>
/// <param name="bucket">对象名</param>
public void GetObject(string bucket, string key)
{
  try
  {
    var result = nosClient.GetObject(bucket, key);
    Console.WriteLine(result.Content);
    Console.WriteLine("Get object succeeded");
  }
  catch (NosException ex)
  {
  Console.WriteLine("Failed with HTTPStatus: {0}; \nErrorCode: {1}; \nErrorMessage: {2}; \nRequestID:{3}; \nResource:{4}",
  ex.StatusCode, ex.ErrorCode, ex.Message, ex.RequestId, ex.Resource);
  }
  catch (Exception ex)
  {
    Console.WriteLine("Failed with error info: {0}", ex.Message);
  }
}

下载文件到本地文件

以下源代码实现将 NOS 文件下载到本地文件:

// 初始化 NosClient
var nosClient = new NosClient(endpoint, accessKeyId, accessKeySecret);

/// <summary>
/// 下载文件到本地
/// </summary>
/// <param name="bucket">桶名</param>
/// <param name="bucket">对象名</param>
/// <param name="bucket">下载到的本地文件</param>
public void GetObject(string bucket, string key, string fileToDownload)
{
  try
  {
    nosClient.GetObject(bucket, key, fileToDownload);
    Console.WriteLine("Get object succeeded");
  }
  catch (NosException ex)
  {
    Console.WriteLine("Failed with HTTPStatus: {0}; \nErrorCode: {1}; \nErrorMessage: {2}; \nRequestID:{3}; \nResource:{4}",
    ex.StatusCode, ex.ErrorCode, ex.Message, ex.RequestId, ex.Resource);
  }
  catch (Exception ex)
  {
    Console.WriteLine("Failed with error info: {0}", ex.Message);
  }
}

指定范围下载

如果存储在 NOS 中的文件较大，并且您只需要其中的一部分内容，您可以使用范围下载，下载指定范围的数据，如果指定的下载范围为”0-100”，则返回结果为第 0 字节到第 100 字节的数据，返回的数据包含第 100 字节，即 range=0-100，如果指定的范围无效则下载整个文件，以下源代码获取 range=0-100 字节的内容:

// 初始化 NosClient
var nosClient = new NosClient(endpoint, accessKeyId, accessKeySecret);

/// <summary>
/// 指定范围下载
/// </summary>
/// <param name="bucket">桶名</param>
/// <param name="bucket">对象名</param>
/// <param name="bucket">下载到的本地文件</param>
public void GetObject(string bucketName, string key, string fileToDownload)
{
  try
  {
    var request = new GetObjectRequest(bucketName, key);
    request.Range = "bytes=0-100";
    var result = nosClient.GetObject(request,fileToDownload);
    Console.WriteLine("Get object succeeded");
  }
  catch (NosException ex)
  {
    Console.WriteLine("Failed with HTTPStatus: {0}; \nErrorCode: {1}; \nErrorMessage: {2}; \nRequestID:{3}; \nResource:{4}",
    ex.StatusCode, ex.ErrorCode, ex.Message, ex.RequestId, ex.Resource);
  }
  catch (Exception ex)
  {
    Console.WriteLine("Failed with error info: {0}", ex.Message);
  }
}

条件下载

下载文件时，可以指定限定条件，满足限定条件时下载，不满足时报错，不下载文件。可以使用的限定条件如下：

// 初始化 NosClient
var nosClient = new NosClient(endpoint, accessKeyId, accessKeySecret);

/// <summary>
/// 指定条件下载
/// </summary>
/// <param name="bucket">桶名</param>
/// <param name="bucket">对象名</param>
/// <param name="bucket">下载到的本地文件</param>
public void GetObject(string bucketName, string key, string fileToDownload)
{
  try
  {
    var request = new GetObjectRequest(bucketName, key);
    request.IfModifiedSince = new DateTime(2016, 11, 13, 14, 47, 53);;
    var result = nosClient.GetObject(request,fileToDownload);
    Console.WriteLine("Get object succeeded");
  }
  catch (NosException ex)
  {
    Console.WriteLine("Failed with HTTPStatus: {0}; \nErrorCode: {1}; \nErrorMessage: {2}; \nRequestID:{3}; \nResource:{4}",
    ex.StatusCode, ex.ErrorCode, ex.Message, ex.RequestId, ex.Resource);
  }
  catch (Exception ex)
  {
    Console.WriteLine("Failed with error info: {0}", ex.Message);
  }
}