Java

Azure Blob - Get Tags (Check if Blob Exists)

See more Azure Cloud Storage Examples

Gets the user-defined tags for a specified blob. This can also be used as a way to check to see if a blob exists. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkRest rest = new CkRest();

    // Connect to the Azure Storage Blob Service
    boolean bTls = true;
    int port = 443;
    boolean bAutoReconnect = true;
    // In this example, the storage account name is "chilkat".
    success = rest.Connect("chilkat.blob.core.windows.net",port,bTls,bAutoReconnect);
    if (success != true) {
        System.out.println(rest.lastErrorText());
        return;
        }

    // Provide Azure Cloud credentials for the REST call.
    CkAuthAzureStorage azAuth = new CkAuthAzureStorage();
    azAuth.put_AccessKey("AZURE_ACCESS_KEY");
    // The account name used here should match the 1st part of the domain passed in the call to Connect (above).
    azAuth.put_Account("chilkat");
    azAuth.put_Scheme("SharedKey");
    azAuth.put_Service("Blob");
    // This causes the "x-ms-version: 2021-08-06" header to be automatically added.
    azAuth.put_XMsVersion("2021-08-06");
    success = rest.SetAuthAzureStorage(azAuth);

    // Note: The application does not need to explicitly set the following
    // headers: Content-Length, x-ms-date, Authorization.  These headers
    // are automatically set by Chilkat.

    // The Azure blob container is "test", the file is "helloWorld.txt"
    // Add "?comp=tags" to get the user-defined tags instead of the actual blob content.
    CkStringBuilder sb = new CkStringBuilder();
    success = rest.FullRequestNoBodySb("GET","/test/helloWorldajdfadf.txt?comp=tags",sb);
    if (success == false) {
        // Examine the request/response to see what happened.
        System.out.println("response status code = " + rest.get_ResponseStatusCode());
        System.out.println("response status text = " + rest.responseStatusText());
        System.out.println("response header: " + rest.responseHeader());
        System.out.println("---");
        System.out.println("LastRequestStartLine: " + rest.lastRequestStartLine());
        System.out.println("LastRequestHeader: " + rest.lastRequestHeader());
        return;
        }

    // A typical blob with no tags will return this:

    // <?xml version="1.0" encoding="utf-8"?>
    // <Tags><TagSet/></Tags>

    // If the blob does not exist, you get this:

    // <?xml version="1.0" encoding="utf-8"?>
    // <Error>
    //     <Code>BlobNotFound</Code>
    //     <Message>The specified blob does not exist.
    // 	RequestId:fcfefdd9-301e-001a-2135-3a23d2000000
    // 	Time:2023-02-06T14:17:00.7805577Z
    //     </Message>
    // </Error>

    System.out.println(sb.getAsString());

    // To see if we got Tags or an Error, then examine the XML.
    CkXml xml = new CkXml();
    xml.LoadSb(sb,true);

    // Examine the tag..
    if (xml.TagEquals("Tags") == true) {
        System.out.println("Blob exists!");
        }
    else {

        if (xml.ChildContentMatches("Code","BlobNotFound",true) == true) {
            System.out.println("Blob does not exist.");
            }
        else {
            System.out.println("Some other error...");
            }

        }

    System.out.println("Success.");
  }
}