使用Java API从事件网格azure函数访问Blob

Question

背景

Java Azure 函数 2，将 Blob 存储与 blob 的事件网格子序列结合使用，创建函数（见下文）通过事件触发器绑定到的事件。

问题

不清楚如何从Azure函数绑定blob(请参见< code > @ Blob Input Java annotation)输入Blob绑定，该文档说明了这些函数，但不确定在Java API中是否可能，这与C#中的情况不同。

当函数被调用时，使用@BlobInput注释，没有任何内容绑定到contentvaraible，因此一旦到达content变量所在的行，它会导致一个空指针。

基于留档的path="{data.url}"允许您访问传递给函数的事件数据。从事件传递的数据也全部绑定到EventSchema事件POJO（有关事件的示例，请参阅下面）。

< code > @ storage account(" azurewebjobstorage ")链接到默认情况下通过函数配置存储和设置的属性，这是正确的。

试

已部署的 azure 函数：

@StorageAccount("AzureWebJobsStorage")
@FunctionName("myfunc")
public void run(@EventGridTrigger(name = "blobeventgrid") EventSchema event,
                @BlobInput(name = "zipfile",dataType = "binary",path = "{data.url}") byte[] content,
                final ExecutionContext context) {
    context.getLogger().info("Java Event Grid trigger function executed.");
    context.getLogger().info("Id: " + event.id);
    context.getLogger().info("Data: " + event.data);
    context.getLogger().info("zip file: " + content.length);
}

示例事件网格事件

{
  "topic": "/subscriptions/<omitted>/resourceGroups/java-functions-group/providers/Microsoft.Storage/storageAccounts/<omitted storageaccount>",
  "subject": "/blobServices/default/containers/mycontainer/blobs/compressed.zip",
  "eventType": "Microsoft.Storage.BlobCreated",
  "eventTime": "2019-10-02T12:46:33.2915427Z",
  "id": "<omitted>",
  "data": {
  "api": "PutBlob",
  "clientRequestId": "<omitted>",
  "requestId": "<omitted>",
  "eTag": "<omitted>",
  "contentType": "application/zip",
  "contentLength": 32460,
  "blobType": "BlockBlob",
  "url": "https://<omitted storageaccount>.blob.core.windows.net/mycontainer/compressed.zip",
  "sequencer": "<omitted>",
  "storageDiagnostics": {
  "batchId": "<omitted>"
    }
  },
  "dataVersion": "",
  "metadataVersion": "1"
}

本地运行函数的日志（远程相同）

[10/05/2019 18:48:16] Executing HTTP request: {
[10/05/2019 18:48:16]   "requestId": "299a3870-98cf-41cf-b418-7cdb33c1f1c7",
[10/05/2019 18:48:16]   "method": "POST",
[10/05/2019 18:48:16]   "uri": "/runtime/webhooks/EventGrid"
[10/05/2019 18:48:16] }
[10/05/2019 18:48:17] Executing 'Functions.myFunc' (Reason='EventGrid trigger fired at 2019-10-05T19:48:17.4343990+01:00', Id=82a2f47b-34bc-492f-8b60-12601beb45ee)
[10/05/2019 18:48:18] Java Event Grid trigger function executed.
[10/05/2019 18:48:18] Event content 
[10/05/2019 18:48:18] Subject: /blobServices/default/containers/mycontainer/blobs/zip/compressed.zip
[10/05/2019 18:48:18] Time: Mon Sep 30 20:46:33 BST 2019
[10/05/2019 18:48:18] Id: 7de5edc4-c01e-0107-1bc7-77755f061e49
[10/05/2019 18:48:18] Data: {api=PutBlob, clientRequestId=007dd554-e3bb-11e9-80b4-dca90473b192, requestId=7de5edc4-c01e-0107-1bc7-77755f000000, eTag=0x8D745DEE5936EE3, contentType=application/zip, contentLength=32460.0, blobType=BlockBlob, url=https://<ommitted storage account>.blob.core.windows.net/mycontainer/zip/compressed.zip, sequencer=000000000000000000000000000007E200000000002ab872, storageDiagnostics={batchId=1c15a3b6-2006-0046-00c7-771b19000000}}
[10/05/2019 18:48:18] Executed 'Functions.myFunc' (Failed, Id=82a2f47b-34bc-492f-8b60-12601beb45ee)
[10/05/2019 18:48:18] System.Private.CoreLib: Exception while executing function: Functions.myFunc. System.Private.CoreLib: Result: Failure
[10/05/2019 18:48:18] Exception: NullPointerException: 

因为什么都没有绑定到内容字节[]...

可供替代的

使用AzureJavaSDK，但尝试保持Azure功能的语义学。

Answer 1

你的功能几乎是正确的。根据我的测试，< code>{data.url}的值将是一个http url，如下所示:

https://storagetest789.blob.core.windows.net/test/test.txt

如果设置了正确的存储连接字符串，则绑定将起作用，您将获得内容。

以下是我的证明:

public class Function {

    @FunctionName("StroageEventGrid")
    @StorageAccount("AzureWebJobsStorage")
    public void run(@EventGridTrigger(name = "blobeventgrid") EventSchema event, 
                    @BlobInput(name = "blob",dataType = "binary",path = "{data.url}") byte[] content,
                    final ExecutionContext context) 
    {
        context.getLogger().info((String)event.data.get("url"));
        if(content != null)
            context.getLogger().info("Length: " + content.length);
        else
            context.getLogger().info("Content is null");
    }
}

public class EventSchema {

  public String topic;
  public String subject;
  public String eventType;
  public Date eventTime;
  public String id;
  public String dataVersion;
  public String metadataVersion;
  public Map<String, Object> data;

}

确保它是目标存储帐户的正确连接字符串。

你可以看到我得到了正确的结果。

所以，我建议您检查您的连接字符串设置。默认情况下，您的本地测试设置不会更新到云，这可能会导致此问题。