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.servlet.mvc;
18:
19: import javax.servlet.http.HttpServletRequest;
20:
21: /**
22: * Supports last-modified HTTP requests to facilitate content caching.
23: * Same contract as for the Servlet API's <code>getLastModified</code> method.
24: *
25: * <p>Delegated to by a HandlerAdapter's <code>getLastModified</code> implementation.
26: * By default, any Controller or HttpRequestHandler within Spring's default framework
27: * can implement this interface to enable last-modified checking.
28: *
29: * @author Rod Johnson
30: * @author Juergen Hoeller
31: * @see javax.servlet.http.HttpServlet#getLastModified
32: * @see Controller
33: * @see SimpleControllerHandlerAdapter
34: * @see org.springframework.web.HttpRequestHandler
35: * @see HttpRequestHandlerAdapter
36: */
37: public interface LastModified {
38:
39: /**
40: * Same contract as for HttpServlet's <code>getLastModified</code> method.
41: * Invoked <b>before</b> request processing.
42: * <p>The return value will be sent to the HTTP client as Last-Modified header,
43: * and compared with If-Modified-Since headers that the client sends back.
44: * The content will only get regenerated if there has been a modification.
45: * @param request current HTTP request
46: * @return the time the underlying resource was last modified, or -1
47: * meaning that the content must always be regenerated
48: * @see org.springframework.web.servlet.HandlerAdapter#getLastModified
49: * @see javax.servlet.http.HttpServlet#getLastModified
50: */
51: long getLastModified(HttpServletRequest request);
52:
53: }
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