Azure Functions 的 Azure Blob 存储输入绑定Azure Blob storage input binding for Azure Functions

以下示例演示使用一个队列触发器和一个 blob 输入绑定的 C# 函数。The following example is a C# function that uses a queue trigger and an input blob binding. 队列消息包含该 blob 的名称，函数记录该 blob 的大小。The queue message contains the name of the blob, and the function logs the size of the blob.

[FunctionName("BlobInput")]
public static void Run(
    [QueueTrigger("myqueue-items")] string myQueueItem,
    [Blob("samples-workitems/{queueTrigger}", FileAccess.Read)] Stream myBlob,
    ILogger log)
{
    log.LogInformation($"BlobInput processed blob\n Name:{myQueueItem} \n Size: {myBlob.Length} bytes");
}

以下示例演示 function.json 文件中的 blob 输入和输出绑定，以及使用这些绑定的 C# 脚本 (.csx) 代码。The following example shows blob input and output bindings in a function.json file and C# script (.csx) code that uses the bindings. 此函数创建文本 blob 的副本。The function makes a copy of a text blob. 该函数由包含要复制的 Blob 名称的队列消息触发。The function is triggered by a queue message that contains the name of the blob to copy. 新 Blob 名为 {originalblobname}-Copy。The new blob is named {originalblobname}-Copy.

在 function.json 文件中，queueTrigger 元数据属性用于指定 path 属性中的 Blob 名称：In the function.json file, the queueTrigger metadata property is used to specify the blob name in the path properties:

{
  "bindings": [
    {
      "queueName": "myqueue-items",
      "connection": "MyStorageConnectionAppSetting",
      "name": "myQueueItem",
      "type": "queueTrigger",
      "direction": "in"
    },
    {
      "name": "myInputBlob",
      "type": "blob",
      "path": "samples-workitems/{queueTrigger}",
      "connection": "MyStorageConnectionAppSetting",
      "direction": "in"
    },
    {
      "name": "myOutputBlob",
      "type": "blob",
      "path": "samples-workitems/{queueTrigger}-Copy",
      "connection": "MyStorageConnectionAppSetting",
      "direction": "out"
    }
  ],
  "disabled": false
}

配置部分解释了这些属性。The configuration section explains these properties.

C# 脚本代码如下所示：Here's the C# script code:

public static void Run(string myQueueItem, string myInputBlob, out string myOutputBlob, ILogger log)
{
    log.LogInformation($"C# Queue trigger function processed: {myQueueItem}");
    myOutputBlob = myInputBlob;
}

下面的示例展示了 function.json 文件中的 blob 输入和输出绑定，以及使用这些绑定的 JavaScript 代码。The following example shows blob input and output bindings in a function.json file and JavaScript code that uses the bindings. 该函数创建 Blob 的副本。The function makes a copy of a blob. 该函数由包含要复制的 Blob 名称的队列消息触发。The function is triggered by a queue message that contains the name of the blob to copy. 新 Blob 名为 {originalblobname}-Copy。The new blob is named {originalblobname}-Copy.

在 function.json 文件中，queueTrigger 元数据属性用于指定 path 属性中的 Blob 名称：In the function.json file, the queueTrigger metadata property is used to specify the blob name in the path properties:

{
  "bindings": [
    {
      "queueName": "myqueue-items",
      "connection": "MyStorageConnectionAppSetting",
      "name": "myQueueItem",
      "type": "queueTrigger",
      "direction": "in"
    },
    {
      "name": "myInputBlob",
      "type": "blob",
      "path": "samples-workitems/{queueTrigger}",
      "connection": "MyStorageConnectionAppSetting",
      "direction": "in"
    },
    {
      "name": "myOutputBlob",
      "type": "blob",
      "path": "samples-workitems/{queueTrigger}-Copy",
      "connection": "MyStorageConnectionAppSetting",
      "direction": "out"
    }
  ],
  "disabled": false
}

配置部分解释了这些属性。The configuration section explains these properties.

JavaScript 代码如下所示：Here's the JavaScript code:

module.exports = function(context) {
    context.log('Node.js Queue trigger function processed', context.bindings.myQueueItem);
    context.bindings.myOutputBlob = context.bindings.myInputBlob;
    context.done();
};

本部分包含以下示例：This section contains the following examples:

• HTTP 触发器，使用查询字符串查找 blob 名称HTTP trigger, look up blob name from query string
• 队列触发器，接收来自队列消息的 blob 名称Queue trigger, receive blob name from queue message

HTTP 触发器，使用查询字符串查找 blob 名称HTTP trigger, look up blob name from query string

下面的示例显示了一个 Java 函数，该函数使用 HttpTrigger 注释来接收包含 blob 存储容器中某个文件的名称的一个参数。The following example shows a Java function that uses the HttpTrigger annotation to receive a parameter containing the name of a file in a blob storage container. 然后，BlobInput 注释读取该文件并将其作为 byte[] 传递给该函数。The BlobInput annotation then reads the file and passes its contents to the function as a byte[].

  @FunctionName("getBlobSizeHttp")
  @StorageAccount("Storage_Account_Connection_String")
  public HttpResponseMessage blobSize(
    @HttpTrigger(name = "req", 
      methods = {HttpMethod.GET}, 
      authLevel = AuthorizationLevel.ANONYMOUS) 
    HttpRequestMessage<Optional<String>> request,
    @BlobInput(
      name = "file", 
      dataType = "binary", 
      path = "samples-workitems/{Query.file}") 
    byte[] content,
    final ExecutionContext context) {
      // build HTTP response with size of requested blob
      return request.createResponseBuilder(HttpStatus.OK)
        .body("The size of \"" + request.getQueryParameters().get("file") + "\" is: " + content.length + " bytes")
        .build();
  }

队列触发器，接收来自队列消息的 blob 名称Queue trigger, receive blob name from queue message

下面的示例显示了一个 Java 函数，该函数使用 QueueTrigger 注释来接收包含 blob 存储容器中某个文件的名称的一个消息。The following example shows a Java function that uses the QueueTrigger annotation to receive a message containing the name of a file in a blob storage container. 然后，BlobInput 注释读取该文件并将其作为 byte[] 传递给该函数。The BlobInput annotation then reads the file and passes its contents to the function as a byte[].

  @FunctionName("getBlobSize")
  @StorageAccount("Storage_Account_Connection_String")
  public void blobSize(
    @QueueTrigger(
      name = "filename", 
      queueName = "myqueue-items-sample") 
    String filename,
    @BlobInput(
      name = "file", 
      dataType = "binary", 
      path = "samples-workitems/{queueTrigger}") 
    byte[] content,
    final ExecutionContext context) {
      context.getLogger().info("The size of \"" + filename + "\" is: " + content.length + " bytes");
  }

在 Java 函数运行时库中，对其值将来自 Blob 的参数使用 @BlobInput 注释。In the Java functions runtime library, use the @BlobInput annotation on parameters whose value would come from a blob. 可以将此注释与本机 Java 类型、POJO 或使用了 Optional<T> 的可为 null 的值一起使用。This annotation can be used with native Java types, POJOs, or nullable values using Optional<T>.

在 C# 类库中，使用 BlobAttribute。In C# class libraries, use the BlobAttribute.

该特性的构造函数采用 Blob 的路径，以及一个表示读取或写入的 FileAccess 参数，如以下示例中所示：The attribute's constructor takes the path to the blob and a FileAccess parameter indicating read or write, as shown in the following example:

[FunctionName("BlobInput")]
public static void Run(
    [QueueTrigger("myqueue-items")] string myQueueItem,
    [Blob("samples-workitems/{queueTrigger}", FileAccess.Read)] Stream myBlob,
    ILogger log)
{
    log.LogInformation($"BlobInput processed blob\n Name:{myQueueItem} \n Size: {myBlob.Length} bytes");
}

可以设置 Connection 属性来指定要使用的存储帐户，如以下示例中所示：You can set the Connection property to specify the storage account to use, as shown in the following example:

[FunctionName("BlobInput")]
public static void Run(
    [QueueTrigger("myqueue-items")] string myQueueItem,
    [Blob("samples-workitems/{queueTrigger}", FileAccess.Read, Connection = "StorageConnectionAppSetting")] Stream myBlob,
    ILogger log)
{
    log.LogInformation($"BlobInput processed blob\n Name:{myQueueItem} \n Size: {myBlob.Length} bytes");
}

可以使用 StorageAccount 特性在类、方法或参数级别指定存储帐户。You can use the StorageAccount attribute to specify the storage account at class, method, or parameter level. 有关详细信息，请参阅触发器 - 特性和注释。For more information, see Trigger - attributes and annotations.

C# 脚本不支持特性。Attributes are not supported by C# Script.

JavaScript 不支持特性。Attributes are not supported by JavaScript.

使用 @BlobInput 特性可以访问触发函数的 blob。The @BlobInput attribute gives you access to the blob that triggered the function. 如果将字节数组与特性一起使用，请将 dataType 设置为 binary。If you use a byte array with the attribute, set dataType to binary. 有关详细信息，请参阅输入示例。Refer to the input example for details.

可以将以下参数类型用于 blob 输入绑定：You can use the following parameter types for the blob input binding:

• Stream
• TextReader
• string
• Byte[]
• CloudBlobContainer
• CloudBlobDirectory
• ICloudBlob¹ICloudBlob¹
• CloudBlockBlob¹CloudBlockBlob¹
• CloudPageBlob¹CloudPageBlob¹
• CloudAppendBlob¹CloudAppendBlob¹

¹ function.json 中需有 "inout" 绑定 direction 或 C# 类库中需有 FileAccess.ReadWrite 。¹ Requires "inout" binding direction in function.json or FileAccess.ReadWrite in a C# class library.

如果在尝试绑定到某个存储 SDK 类型时出现错误消息，请确保引用正确的存储 SDK 版本。If you try to bind to one of the Storage SDK types and get an error message, make sure that you have a reference to the correct Storage SDK version.

由于整个 Blob 内容都会加载到内存中，因此，只有当 Blob 较小时才建议绑定到 string 或 Byte[]。Binding to string or Byte[] is only recommended if the blob size is small, as the entire blob contents are loaded into memory. 平时，最好使用 Stream 或 CloudBlockBlob 类型。Generally, it is preferable to use a Stream or CloudBlockBlob type. 有关详细信息，请参阅本文前文中的并发和内存使用情况。For more information, see Concurrency and memory usage earlier in this article.

可以将以下参数类型用于 blob 输入绑定：You can use the following parameter types for the blob input binding:

• Stream
• TextReader
• string
• Byte[]
• CloudBlobContainer
• CloudBlobDirectory
• ICloudBlob¹ICloudBlob¹
• CloudBlockBlob¹CloudBlockBlob¹
• CloudPageBlob¹CloudPageBlob¹
• CloudAppendBlob¹CloudAppendBlob¹

¹ function.json 中需有 "inout" 绑定 direction 或 C# 类库中需有 FileAccess.ReadWrite 。¹ Requires "inout" binding direction in function.json or FileAccess.ReadWrite in a C# class library.

如果在尝试绑定到某个存储 SDK 类型时出现错误消息，请确保引用正确的存储 SDK 版本。If you try to bind to one of the Storage SDK types and get an error message, make sure that you have a reference to the correct Storage SDK version.

由于整个 Blob 内容都会加载到内存中，因此，只有当 Blob 较小时才建议绑定到 string 或 Byte[]。Binding to string or Byte[] is only recommended if the blob size is small, as the entire blob contents are loaded into memory. 平时，最好使用 Stream 或 CloudBlockBlob 类型。Generally, it is preferable to use a Stream or CloudBlockBlob type. 有关详细信息，请参阅本文前文中的并发和内存使用情况。For more information, see Concurrency and memory usage earlier in this article.

使用 context.bindings.<NAME> 访问 blob 数据，其中 <NAME> 与 function.json 中定义的值匹配。Access blob data using context.bindings.<NAME> where <NAME> matches the value defined in function.json.

使用 @BlobInput 特性可以访问触发函数的 blob。The @BlobInput attribute gives you access to the blob that triggered the function. 如果将字节数组与特性一起使用，请将 dataType 设置为 binary。If you use a byte array with the attribute, set dataType to binary. 有关详细信息，请参阅输入示例。Refer to the input example for details.