Add stream base file download support

components/application-mgt/io.entgra.device.mgt.core.application.mgt.common/src/main/java/io/entgra/device/mgt/core/application/mgt/common/services/AppmDataHandler.java

@@ -50,4 +50,16 @@ public interface AppmDataHandler {
      * @throws ApplicationManagementException throws if an error occurs when accessing the file.
      */
     InputStream getAgentStream(String tenantDomain, String deviceType) throws ApplicationManagementException;
+
+    /**
+     * Check if the artifact is existing in the file system
+     *
+     * @param hashVal    Hash Value of the application
+     * @param folderName Folder name
+     * @param fileName   Artifact file name
+     * @param tenantId   Tenant id
+     * @return true if the artifact exists, otherwise false
+     * @throws ApplicationManagementException if error occurred while checking the existence of the artifact
+     */
+    boolean isArtifactExists(String hashVal, String folderName, String fileName, int tenantId) throws ApplicationManagementException;
 }

components/application-mgt/io.entgra.device.mgt.core.application.mgt.core/src/main/java/io/entgra/device/mgt/core/application/mgt/core/impl/AppmDataHandlerImpl.java

@@ -35,6 +35,7 @@ import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import java.io.File;
 import java.io.InputStream;
 import java.util.Map;
 
@@ -136,4 +137,11 @@ public class AppmDataHandlerImpl implements AppmDataHandler {
             throw new ApplicationManagementException(msg, e);
         }
     }
+
+    @Override
+    public boolean isArtifactExists(String hashVal, String folderName, String fileName, int tenantId) throws BadRequestException {
+        validateArtifactDownloadRequest(tenantId, hashVal, folderName, fileName);
+        return new File(APIUtil.
+                getApplicationStorageManager().getAbsolutePathOfFile(hashVal, folderName, fileName, tenantId)).exists();
+    }
 }