com.vaadin.server.RequestHandler Maven / Gradle / Ivy
/*
* Copyright (C) 2000-2024 Vaadin Ltd
*
* This program is available under Vaadin Commercial License and Service Terms.
*
* See for the full
* license.
*/
package com.vaadin.server;
import java.io.IOException;
import java.io.Serializable;
import com.vaadin.ui.UI;
/**
* Handler for producing a response to HTTP requests. Handlers can be either
* added on a {@link VaadinService service} level, common for all users, or on a
* {@link VaadinSession session} level for only a single user.
*/
@FunctionalInterface
public interface RequestHandler extends Serializable {
/**
* Called when a request needs to be handled. If a response is written, this
* method should return true to indicate that no more request
* handlers should be invoked for the request.
*
* Note that request handlers by default do not lock the session. If you are
* using VaadinSession or anything inside the VaadinSession you must ensure
* the session is locked. This can be done by extending
* {@link SynchronizedRequestHandler} or by using
* {@link VaadinSession#accessSynchronously(Runnable)} or
* {@link UI#accessSynchronously(Runnable)}.
*
*
* @param session
* The session for the request
* @param request
* The request to handle
* @param response
* The response object to which a response can be written.
* @return true if a response has been written and no further request
* handlers should be called, otherwise false
* @throws IOException
* If an IO error occurred
*/
boolean handleRequest(VaadinSession session, VaadinRequest request,
VaadinResponse response) throws IOException;
}