Code Snippet. Intercepting "On Save" Action in IntelliJIDEA

1. Add the following to META-INF/plugin.xml of your plug-in:

<application-components>
   <component>
      <implementation-class>my.plugin.OnFileSaveComponent</implementation-class>
    </component>
 </application-components>

2. Implement com.intellij.openapi.components.ApplicationComponent:

package my.plugin;

import com.intellij.AppTopics;
import com.intellij.openapi.application.ApplicationManager;
import com.intellij.openapi.components.ApplicationComponent;
import com.intellij.openapi.editor.Document;
import com.intellij.openapi.fileEditor.FileDocumentManagerAdapter;
import com.intellij.util.messages.MessageBus;
import com.intellij.util.messages.MessageBusConnection;
import org.jetbrains.annotations.NotNull;

public class OnFileSaveComponent implements ApplicationComponent {
  @NotNull
  public String getComponentName() {
    return "My On-Save Component";
  }

  public void initComponent() {
    MessageBus bus = ApplicationManager.getApplication().getMessageBus();

    MessageBusConnection connection = bus.connect();

    connection.subscribe(AppTopics.FILE_DOCUMENT_SYNC, 
      new FileDocumentManagerAdapter() {
      @Override
      public void beforeDocumentSaving(Document document) {
         // create your custom logic here
      }
    });
  }

  public void disposeComponent() {
  }
}

That's it! :)

So how could it be used? If you'd like to perform some synchronization with a remote server on each file save in IntelliJ, probably, this code snippet would help you.