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. Chilkat2 Java

import com.chilkatsoft.chilkat2.AuthAzureStorage;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Rest;
import com.chilkatsoft.chilkat2.StringBuilder;
import com.chilkatsoft.chilkat2.Xml;

public class ChilkatExample {

    public static void main(String[] args) {
        // This example requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        Rest rest = new Rest();

        // 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".
        try {
            rest.connect("chilkat.blob.core.windows.net", port, bTls, bAutoReconnect);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Provide Azure Cloud credentials for the REST call.
        AuthAzureStorage azAuth = new AuthAzureStorage();
        azAuth.setAccessKey("AZURE_ACCESS_KEY");
        // The account name used here should match the 1st part of the domain passed in the call to Connect (above).
        azAuth.setAccount("chilkat");
        azAuth.setScheme("SharedKey");
        azAuth.setService("Blob");
        // This causes the "x-ms-version: 2021-08-06" header to be automatically added.
        azAuth.setXMsVersion("2021-08-06");
        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.
        StringBuilder sb = new StringBuilder();
        try {
            rest.fullRequestNoBodySb("GET", "/test/helloWorldajdfadf.txt?comp=tags", sb);
        } catch (ChilkatException e) {
            // Examine the request/response to see what happened.
            System.out.println("response status code = " + rest.getResponseStatusCode());
            System.out.println("response status text = " + rest.getResponseStatusText());
            System.out.println("response header: " + rest.getResponseHeader());
            System.out.println("---");
            System.out.println("LastRequestStartLine: " + rest.getLastRequestStartLine());
            System.out.println("LastRequestHeader: " + rest.getLastRequestHeader());
            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.
        Xml xml = new Xml();
        xml.loadSb(sb, true);

        // Examine the tag..
        if (xml.tagEquals("Tags")) {
            System.out.println("Blob exists!");
        } else {
            if (xml.childContentMatches("Code", "BlobNotFound", true)) {
                System.out.println("Blob does not exist.");
            } else {
                System.out.println("Some other error...");
            }
        }

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