01: /*
02: * Copyright 2002-2005 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;
18:
19: import java.util.Map;
20:
21: import javax.servlet.http.HttpServletRequest;
22: import javax.servlet.http.HttpServletResponse;
23:
24: /**
25: * MVC View for a web interaction. Implementations are responsible for rendering
26: * content, and exposing the model. A single view exposes multiple model attributes.
27: *
28: * <p>This class and the MVC approach associated with it is discussed in Chapter 12 of
29: * <a href="http://www.amazon.com/exec/obidos/tg/detail/-/0764543857/">Expert One-On-One J2EE Design and Development</a>
30: * by Rod Johnson (Wrox, 2002).
31: *
32: * <p>View implementations may differ widely. An obvious implementation would be
33: * JSP-based. Other implementations might be XSLT-based, or use an HTML generation library.
34: * This interface is designed to avoid restricting the range of possible implementations.
35: *
36: * <p>Views should be beans. They are likely to be instantiated as beans by a ViewResolver.
37: * As this interface is stateless, view implementations should be thread-safe.
38: *
39: * @author Rod Johnson
40: * @see org.springframework.web.servlet.view.AbstractView
41: * @see org.springframework.web.servlet.view.InternalResourceView
42: */
43: public interface View {
44:
45: /**
46: * Return the content type of the view, if predetermined.
47: * <p>Can be used to check the content type upfront,
48: * before the actual rendering process.
49: * @return the content type String (optionally including a character set),
50: * or <code>null</code> if not predetermined.
51: */
52: String getContentType();
53:
54: /**
55: * Render the view given the specified model.
56: * <p>The first step will be preparing the request: In the JSP case,
57: * this would mean setting model objects as request attributes.
58: * The second step will be the actual rendering of the view,
59: * for example including the JSP via a RequestDispatcher.
60: * @param model Map with name Strings as keys and corresponding model
61: * objects as values (Map can also be <code>null</code> in case of empty model)
62: * @param request current HTTP request
63: * @param response HTTP response we are building
64: * @throws Exception if rendering failed
65: */
66: void render(Map model, HttpServletRequest request,
67: HttpServletResponse response) throws Exception;
68:
69: }
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