01: /*
02: * Copyright 2002-2006 the original author or authors.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS,
12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13: * See the License for the specific language governing permissions and
14: * limitations under the License.
15: */
16:
17: package org.springframework.web;
18:
19: import java.io.IOException;
20:
21: import javax.servlet.ServletException;
22: import javax.servlet.http.HttpServletRequest;
23: import javax.servlet.http.HttpServletResponse;
24:
25: /**
26: * Plain handler interface for components that process HTTP requests,
27: * analogous to a Servlet. Only throws ServletException and IOException,
28: * to allow for usage within any HttpServlet. Essentially the direct
29: * equivalent of an HttpServlet, reduced to a handle method.
30: *
31: * <p>The easiest way to expose an HttpRequestHandler bean in Spring style
32: * is to define it in Spring's root web application context and define
33: * an HttpRequestHandlerServlet in <code>web.xml</code>, pointing at the
34: * target HttpRequestHandler bean through its servlet-name which needs
35: * to match the target bean name.
36: *
37: * <p>Supported as a handler type within Spring's DispatcherServlet,
38: * being able to leverage the dispatcher's advanced mapping and interception
39: * facilities. This is the recommended way of exposing an HttpRequestHandler,
40: * while keeping the handler implementations free of direct dependencies
41: * on a DispatcherServlet environment.
42: *
43: * <p>Typically implemented to generate binary responses directly,
44: * with no separate view resource involved. This differentiates it from
45: * a Controller within Spring's Web MVC framework. The lack of a ModelAndView
46: * return value gives a clearer signature to callers other than the
47: * DispatcherServlet, indicating there will never be a view to render.
48: *
49: * <p>As of Spring 2.0, Spring's HTTP-based remote exporters, such as
50: * HttpInvokerServiceExporter and HessianServiceExporter, implement this
51: * interface rather than the more extensive Controller interface,
52: * for minimal dependencies on Spring-specific web infrastructure.
53: *
54: * <p>Note that RequestHandlers can optionally implement the LastModified
55: * interface, just like Controllers can, provided that they run within
56: * Spring's DispatcherServlet.
57: *
58: * @author Juergen Hoeller
59: * @since 2.0
60: * @see org.springframework.web.context.support.HttpRequestHandlerServlet
61: * @see org.springframework.web.servlet.DispatcherServlet
62: * @see org.springframework.web.servlet.ModelAndView
63: * @see org.springframework.web.servlet.mvc.Controller
64: * @see org.springframework.web.servlet.mvc.LastModified
65: * @see org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter
66: * @see org.springframework.remoting.httpinvoker.HttpInvokerServiceExporter
67: * @see org.springframework.remoting.caucho.HessianServiceExporter
68: * @see org.springframework.remoting.caucho.BurlapServiceExporter
69: */
70: public interface HttpRequestHandler {
71:
72: /**
73: * Process the given request, generating a response.
74: * @param request current HTTP request
75: * @param response current HTTP response
76: * @throws ServletException in case of general errors
77: * @throws IOException in case of I/O errors
78: */
79: void handleRequest(HttpServletRequest request,
80: HttpServletResponse response) throws ServletException,
81: IOException;
82:
83: }
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