如何在 azure 函数中使用 rss 文件

Question

我有从外部来源获取数据的带有 http 触发器的 azure 函数。 在函数内部，我使用这些外部数据创建了 RSS 文件。

我想在收到新数据时更新这个文件（在这种状态下它会删除以前的数据）。

此外，我想知道如何获取此 RSS 文件的 url，以便在逻辑应用程序中使用它。

任何想法都会被采纳。

Function 类如下所示：

public class Function {

private HashMap<String, String> crntNewItemList = new HashMap<>();

@FunctionName("HttpAddFeedItem")
public HttpResponseMessage run(
        @HttpTrigger(name = "req", methods = {HttpMethod.GET, HttpMethod.POST}, authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage<Optional<String>> request,
        final ExecutionContext context) {
    context.getLogger().info("Java HTTP trigger processed a request.");

    // Parse query parameter
    String body = request.getBody().get(); // Get request body

    if (body == null) {
        return request.createResponseBuilder(HttpStatus.BAD_REQUEST).body("Please pass a name on the query string or in the request body").build();
    } else {
        String contentType = request.getHeaders().get("content-type");

        initNewsItemList(contentType, body);

        String copyright = "Copyright hold by XXX";
        String title = "Eclipse and Java Information";
        String description = "Eclipse and Java Information";
        String language = "en";
        String link = "httXX://XXw.XXX.com/";
        Calendar cal = new GregorianCalendar();
        Date creationDate = cal.getTime();
        SimpleDateFormat date_format = new SimpleDateFormat(
                "EEE', 'dd' 'MMM' 'yyyy' 'HH:mm:ss' 'Z", Locale.US);
        String pubdate = date_format.format(creationDate);
        Feed rssFeeder = new Feed(title, link, description, language,
                copyright, pubdate);

        // now add one example entry
        FeedMessage feed = new FeedMessage();
        feed.setTitle(crntNewItemList.get("title"));
        feed.setDescription(crntNewItemList.get("description"));
        feed.setAuthor("nonsense@somewhere.de (XXX)");
        feed.setGuid("htXXs://XXw.XXX.com/tutorials/RSSFeed/article.html");
        feed.setLink(crntNewItemList.get("link"));
        rssFeeder.getMessages().add(feed);

        // now write the file
        RSSFeedWriter writer = new RSSFeedWriter(rssFeeder, "articles.rss");
        try {
            writer.write();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return request.createResponseBuilder(HttpStatus.OK).body("success").build();
    }
}

****更新****
RSSFeedWriter 类是：

public class RSSFeedWriter {

    private String outputFile;
    private Feed rssfeed;

    public RSSFeedWriter(Feed rssfeed, String outputFile) {
        this.rssfeed = rssfeed;
        this.outputFile = outputFile;
    }

    public void write() throws Exception {

        // create a XMLOutputFactory
        XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();

        // create XMLEventWriter
        XMLEventWriter eventWriter = outputFactory
                .createXMLEventWriter(new FileOutputStream(outputFile));

        // create a EventFactory

        XMLEventFactory eventFactory = XMLEventFactory.newInstance();
        XMLEvent end = eventFactory.createDTD("\n");

        // create and write Start Tag

        StartDocument startDocument = eventFactory.createStartDocument();

        eventWriter.add(startDocument);

        // create open tag
        eventWriter.add(end);

        StartElement rssStart = eventFactory.createStartElement("", "", "rss");
        eventWriter.add(rssStart);
        eventWriter.add(eventFactory.createAttribute("version", "2.0"));
        eventWriter.add(end);

        eventWriter.add(eventFactory.createStartElement("", "", "channel"));
        eventWriter.add(end);

        // Write the different nodes

        createNode(eventWriter, "title", rssfeed.getTitle());

        createNode(eventWriter, "link", rssfeed.getLink());

        createNode(eventWriter, "description", rssfeed.getDescription());

        createNode(eventWriter, "language", rssfeed.getLanguage());

        createNode(eventWriter, "copyright", rssfeed.getCopyright());

        createNode(eventWriter, "pubdate", rssfeed.getPubDate());

        for (FeedMessage entry : rssfeed.getMessages()) {
            eventWriter.add(eventFactory.createStartElement("", "", "item"));
            eventWriter.add(end);
            createNode(eventWriter, "title", entry.getTitle());
            createNode(eventWriter, "description", entry.getDescription());
            createNode(eventWriter, "link", entry.getLink());
            createNode(eventWriter, "author", entry.getAuthor());
            createNode(eventWriter, "guid", entry.getGuid());
            eventWriter.add(end);
            eventWriter.add(eventFactory.createEndElement("", "", "item"));
            eventWriter.add(end);

        }

        eventWriter.add(end);
        eventWriter.add(eventFactory.createEndElement("", "", "channel"));
        eventWriter.add(end);
        eventWriter.add(eventFactory.createEndElement("", "", "rss"));

        eventWriter.add(end);

        eventWriter.add(eventFactory.createEndDocument());

        eventWriter.close();
    }

    private void createNode(XMLEventWriter eventWriter, String name,

                            String value) throws XMLStreamException {
        XMLEventFactory eventFactory = XMLEventFactory.newInstance();
        XMLEvent end = eventFactory.createDTD("\n");
        XMLEvent tab = eventFactory.createDTD("\t");
        // create Start node
        StartElement sElement = eventFactory.createStartElement("", "", name);
        eventWriter.add(tab);
        eventWriter.add(sElement);
        // create Content
        Characters characters = eventFactory.createCharacters(value);
        eventWriter.add(characters);
        // create End node
        EndElement eElement = eventFactory.createEndElement("", "", name);
        eventWriter.add(eElement);
        eventWriter.add(end);
    }
}

Answer 1

关于这个问题，我建议您创建 rss 文件并将该文件上传到 Azure blob。在 Azure 逻辑应用中，我们可以使用Azure Blob Storage Connector 来处理 rss 文件。

更多详情，请参考以下步骤

1. 安装 Azure Blob 存储 SDK

 <dependency>
            <groupId>com.microsoft.azure</groupId>
            <artifactId>azure-storage</artifactId>
            <version>8.4.0</version>
        </dependency>

1. 更新 RSSFeedWriter 类

public class RSSFeedWriter {
    private String outputFile; // the file name
    private Feed rssfeed;
    private String connectionString; // the storage account connection string

    public RSSFeedWriter(Feed rssfeed, String outputFile) {
        this.rssfeed = rssfeed;
        this.outputFile = outputFile;
    }
    public RSSFeedWriter(Feed rssfeed, String outputFile,String connectionString) {
        this.rssfeed = rssfeed;
        this.outputFile = outputFile;
        this.connectionString=connectionString;
    }
    public void write() throws Exception {

        CloudStorageAccount storageAccount = CloudStorageAccount.parse(connectionString);
        CloudBlobClient blobClient = storageAccount.createCloudBlobClient();
        CloudBlobContainer container = blobClient.getContainerReference("test");
        CloudBlockBlob blob =container.getBlockBlobReference("test.rss");
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
         // create a XMLOutputFactory
        XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();

        // create XMLEventWriter
        XMLEventWriter eventWriter = outputFactory
                .createXMLEventWriter(outputStream);
        // create rss 
        ...

        // upload rss to Azure blob
        blob.upload(new ByteArrayInputStream(outputStream.toByteArray()),outputStream.toByteArray().length);
        outputStream.close();
    }

    private void createNode(XMLEventWriter eventWriter, String name,

                            String value) throws XMLStreamException {
        XMLEventFactory eventFactory = XMLEventFactory.newInstance();
        XMLEvent end = eventFactory.createDTD("\n");
        XMLEvent tab = eventFactory.createDTD("\t");
        // create Start node
        StartElement sElement = eventFactory.createStartElement("", "", name);
        eventWriter.add(tab);
        eventWriter.add(sElement);
        // create Content
        Characters characters = eventFactory.createCharacters(value);
        eventWriter.add(characters);
        // create End node
        EndElement eElement = eventFactory.createEndElement("", "", name);
        eventWriter.add(eElement);
        eventWriter.add(end);
    }

}

1. 更新功能码

@FunctionName("HttpAddFeedItem")
public HttpResponseMessage run(
        @HttpTrigger(name = "req", methods = {HttpMethod.GET, HttpMethod.POST}, authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage<Optional<String>> request,
        final ExecutionContext context) {
    context.getLogger().info("Java HTTP trigger processed a request.");

 ...

// get the storage account connection string you store in app settings or local.settings.json with the key name
String connectionString = System.getenv("AzureWebJobsStorage"); 
        String outputFile=""; // the file name
        RSSFeedWriter writer = new RSSFeedWriter(rssFeeder, outputFile,connectionString);
        try {
            writer.write();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return request.createResponseBuilder(HttpStatus.OK).body("success").build();
    }
}

---

更新

如果您想在浏览器中通过blob URL直接访问rss文件，请参考以下步骤

1. 请将容器公共访问级别设置为Public read access for blobs only。更多详情请参考document

2. 请确保 blob 的内容类型正确。 rss 文件的内容类型可以是application/rss+xml。关于如何更改内容类型，请参考以下代码

 CloudStorageAccount storageAccount = CloudStorageAccount.parse(Constr)
CloudBlobClient blobClient = storageAccount.createCloudBlobClient();
        CloudBlobContainer container = blobClient.getContainerReference("test");
        if(!container.exists()){
            container.create();

        }
 CloudBlockBlob blob =container.getBlockBlobReference("test.rss");
 blob.getProperties().setContentType("application/rss+xml");

        blob.uploadProperties();

之后，我们可以在浏览器中访问file