Open docker file with text editor by default (#4569)

* Open docker file with text editor by default

* Fix checkstyle

Author: Flanker32

PluginsAndFeatures/azure-toolkit-for-eclipse/com.microsoft.azuretools.container/src/main/java/com/microsoft/azuretools/container/handlers/DockerizeHandler.java

@@ -31,7 +31,6 @@
 import org.eclipse.core.commands.ExecutionEvent;
 import org.eclipse.core.commands.ExecutionException;
 import org.eclipse.core.resources.IFile;
-import org.eclipse.core.resources.IMarker;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.runtime.CoreException;
@@ -50,15 +49,17 @@
 
 public class DockerizeHandler extends AzureAbstractHandler {
 
+    private static final String DEFAULT_TEXT_EDITOR = "org.eclipse.ui.DefaultTextEditor";
+
     @Override
     public Object onExecute(ExecutionEvent event) throws ExecutionException {
-        IProject project = PluginUtil.getSelectedProject();
+        final IProject project = PluginUtil.getSelectedProject();
         ConsoleLogger.info(Constant.MESSAGE_ADDING_DOCKER_SUPPORT);
         EventUtil.executeWithLog(WEBAPP, CREATE_DOCKER_FILE, (operation) -> {
             if (project == null) {
                 throw new Exception(Constant.ERROR_NO_SELECTED_PROJECT);
             }
-            String basePath = project.getLocation().toString();
+            final String basePath = project.getLocation().toString();
             String dockerFileContent = Constant.DOCKERFILE_CONTENT_TOMCAT;
             String artifactRelativePath = Constant.DOCKERFILE_ARTIFACT_PLACEHOLDER;
             if (MavenUtils.isMavenProject(project)) {
@@ -92,16 +93,20 @@ public Object onExecute(ExecutionEvent event) throws ExecutionException {
     }
 
     private void openFile(IFile file) {
-        IWorkbenchWindow window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
-        IWorkbenchPage page = window.getActivePage();
-        IMarker marker;
+        final IWorkbenchWindow window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
+        final IWorkbenchPage page = window.getActivePage();
         try {
-            marker = file.createMarker(IMarker.TEXT);
-            IDE.openEditor(page, marker);
-            marker.delete();
-
+            if (isDefaultTextEditorExists(page)) {
+                IDE.openEditor(page, file, "org.eclipse.ui.DefaultTextEditor");
+            } else {
+                IDE.openEditor(page, file);
+            }
         } catch (CoreException e) {
             e.printStackTrace();
         }
     }
+
+    private boolean isDefaultTextEditorExists(IWorkbenchPage page) {
+        return page.getWorkbenchWindow().getWorkbench().getEditorRegistry().findEditor(DEFAULT_TEXT_EDITOR) != null;
+    }
 }