com.vaadin.server.RequestHandler Maven / Gradle / Ivy
/*
* Copyright 2000-2014 Vaadin Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the 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.
*/
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;
}