/*
* Copyright 2002-2007 the original author or authors.
*
* 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 org.springframework.web;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Plain handler interface for components that process HTTP requests,
* analogous to a Servlet. Only declares {@link javax.servlet.ServletException}
* and {@link java.io.IOException}, to allow for usage within any
* {@link javax.servlet.http.HttpServlet}}. This interface is ssentially the
* direct equivalent of an HttpServlet, reduced to a central handle method.
*
* <p>The easiest way to expose an HttpRequestHandler bean in Spring style
* is to define it in Spring's root web application context and define
* an {@link org.springframework.web.context.support.HttpRequestHandlerServlet}
* in <code>web.xml</code>, pointing at the target HttpRequestHandler bean
* through its <code>servlet-name</code> which needs to match the target bean name.
*
* <p>Supported as a handler type within Spring's
* {@link org.springframework.web.servlet.DispatcherServlet}, being able
* to interact with the dispatcher's advanced mapping and interception
* facilities. This is the recommended way of exposing an HttpRequestHandler,
* while keeping the handler implementations free of direct dependencies
* on a DispatcherServlet environment.
*
* <p>Typically implemented to generate binary responses directly,
* with no separate view resource involved. This differentiates it from a
* {@link org.springframework.web.servlet.mvc.Controller} within Spring's Web MVC
* framework. The lack of a {@link org.springframework.web.servlet.ModelAndView}
* return value gives a clearer signature to callers other than the
* DispatcherServlet, indicating that there will never be a view to render.
*
* <p>As of Spring 2.0, Spring's HTTP-based remote exporters, such as
* {@link org.springframework.remoting.httpinvoker.HttpInvokerServiceExporter}
* and {@link org.springframework.remoting.caucho.HessianServiceExporter},
* implement this interface rather than the more extensive Controller interface,
* for minimal dependencies on Spring-specific web infrastructure.
*
* <p>Note that HttpRequestHandlers may optionally implement the
* {@link org.springframework.web.servlet.mvc.LastModified} interface,
* just like Controllers can, <i>provided that they run within Spring's
* DispatcherServlet</i>. However, this is usually not necessary, since
* HttpRequestHandlers typically only support POST requests to begin with.
* Alternatively, a handler may implement the "If-Modified-Since" HTTP
* header processing manually within its <code>handle</code> method.
*
* @author Juergen Hoeller
* @since 2.0
* @see org.springframework.web.context.support.HttpRequestHandlerServlet
* @see org.springframework.web.servlet.DispatcherServlet
* @see org.springframework.web.servlet.ModelAndView
* @see org.springframework.web.servlet.mvc.Controller
* @see org.springframework.web.servlet.mvc.LastModified
* @see org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter
* @see org.springframework.remoting.httpinvoker.HttpInvokerServiceExporter
* @see org.springframework.remoting.caucho.HessianServiceExporter
* @see org.springframework.remoting.caucho.BurlapServiceExporter
*/
public interface HttpRequestHandler {
/**
* Process the given request, generating a response.
* @param request current HTTP request
* @param response current HTTP response
* @throws ServletException in case of general errors
* @throws IOException in case of I/O errors
*/
void handleRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException;
}