1 /*
2 * Copyright 2007 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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.oxm.support;
18
19 import java.io.ByteArrayOutputStream;
20 import java.util.Iterator;
21 import java.util.Map;
22 import javax.servlet.ServletException;
23 import javax.servlet.ServletOutputStream;
24 import javax.servlet.http.HttpServletRequest;
25 import javax.servlet.http.HttpServletResponse;
26 import javax.xml.transform.stream.StreamResult;
27
28 import org.springframework.beans.BeansException;
29 import org.springframework.oxm.Marshaller;
30 import org.springframework.util.Assert;
31 import org.springframework.web.servlet.View;
32 import org.springframework.web.servlet.view.AbstractUrlBasedView;
33
34 /**
35 * Spring-MVC {@link View} that allows for response context to be rendered as the result of marshalling by a {@link
36 * Marshaller}.
37 * <p/>
38 * The Object to be marshalled is supplied as a parameter in the model and then {@linkplain #locateToBeMarshalled(Map)
39 * detected} during response rendering. Users can either specify a specific entry in the model via the {@link
40 * #setModelKey(String) sourceKey} property or have Spring locate the Source object.
41 *
42 * @author Arjen Poutsma
43 * @since 1.5.1
44 */
45 public class MarshallingView extends AbstractUrlBasedView {
46
47 /** Default content type. Overridable as bean property. */
48 public static final String DEFAULT_CONTENT_TYPE = "application/xml";
49
50 private Marshaller marshaller;
51
52 private String modelKey;
53
54 /**
55 * Constructs a new <code>MarshallingView</code> with no {@link Marshaller} set. The marshaller must be set after
56 * construction by invoking {@link #setMarshaller(Marshaller)}.
57 */
58 public MarshallingView() {
59 setContentType(DEFAULT_CONTENT_TYPE);
60 }
61
62 /** Constructs a new <code>MarshallingView</code> with the given {@link Marshaller} set. */
63 public MarshallingView(Marshaller marshaller) {
64 Assert.notNull(marshaller, "'marshaller' must not be null");
65 setContentType(DEFAULT_CONTENT_TYPE);
66 this.marshaller = marshaller;
67 }
68
69 /** Sets the {@link Marshaller} to be used by this view. */
70 public void setMarshaller(Marshaller marshaller) {
71 Assert.notNull(marshaller, "'marshaller' must not be null");
72 this.marshaller = marshaller;
73 }
74
75 /**
76 * Set the name of the model key that represents the object to be marshalled. If not specified, the model map will
77 * be searched for a supported value type.
78 *
79 * @see Marshaller#supports(Class)
80 */
81 public void setModelKey(String modelKey) {
82 this.modelKey = modelKey;
83 }
84
85 protected void initApplicationContext() throws BeansException {
86 Assert.notNull(marshaller, "Property 'marshaller' is required");
87 }
88
89 protected void renderMergedOutputModel(Map model, HttpServletRequest request, HttpServletResponse response)
90 throws Exception {
91 Object toBeMarshalled = locateToBeMarshalled(model);
92 if (toBeMarshalled == null) {
93 throw new ServletException("Unable to locate object to be marshalled in model: " + model);
94 }
95 ByteArrayOutputStream bos = new ByteArrayOutputStream(2048);
96 marshaller.marshal(toBeMarshalled, new StreamResult(bos));
97
98 response.setContentType(getContentType());
99 response.setContentLength(bos.size());
100
101 ServletOutputStream out = response.getOutputStream();
102 bos.writeTo(out);
103 out.flush();
104 }
105
106 /**
107 * Locates the object to be marshalled. The default implementation first attempts to look under the configured
108 * {@linkplain #setModelKey(String) model key}, if any, before attempting to locate an object of {@linkplain
109 * Marshaller#supports(Class) supported type}.
110 *
111 * @param model the model Map
112 * @return the Object to be marshalled (or <code>null</code> if none found)
113 * @throws ServletException if the model object specified by the {@linkplain #setModelKey(String) model key} is not
114 * supported by the marshaller
115 * @see #setModelKey(String)
116 */
117 protected Object locateToBeMarshalled(Map model) throws ServletException {
118 if (this.modelKey != null) {
119 Object o = model.get(this.modelKey);
120 if (!this.marshaller.supports(o.getClass())) {
121 throw new ServletException("Model object [" + o + "] retrieved via key [" + modelKey +
122 "] is not supported by the Marshaller");
123 }
124 return o;
125 }
126 for (Iterator iterator = model.values().iterator(); iterator.hasNext();) {
127 Object o = iterator.next();
128 if (this.marshaller.supports(o.getClass())) {
129 return o;
130 }
131 }
132 return null;
133 }
134 }