/*
* Copyright 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.servlet.view.xml;
import java.io.ByteArrayOutputStream;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.transform.stream.StreamResult;
import org.springframework.beans.BeansException;
import org.springframework.oxm.Marshaller;
import org.springframework.util.Assert;
import org.springframework.util.FileCopyUtils;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.view.AbstractView;
/**
* Spring-MVC {@link View} that allows for response context to be rendered as the result of marshalling by a {@link
* Marshaller}.
*
* <p>The Object to be marshalled is supplied as a parameter in the model and then {@linkplain
* #locateToBeMarshalled(Map) detected} during response rendering. Users can either specify a specific entry in the
* model via the {@link #setModelKey(String) sourceKey} property or have Spring locate the Source object.
*
* @author Arjen Poutsma
* @since 3.0
*/
public class MarshallingView extends AbstractView {
/**
* Default content type. Overridable as bean property.
*/
public static final String DEFAULT_CONTENT_TYPE = "application/xml";
private Marshaller marshaller;
private String modelKey;
/**
* Constructs a new <code>MarshallingView</code> with no {@link Marshaller} set. The marshaller must be set after
* construction by invoking {@link #setMarshaller(Marshaller)}.
*/
public MarshallingView() {
setContentType(DEFAULT_CONTENT_TYPE);
}
/**
* Constructs a new <code>MarshallingView</code> with the given {@link Marshaller} set.
*/
public MarshallingView(Marshaller marshaller) {
Assert.notNull(marshaller, "'marshaller' must not be null");
setContentType(DEFAULT_CONTENT_TYPE);
this.marshaller = marshaller;
}
/**
* Sets the {@link Marshaller} to be used by this view.
*/
public void setMarshaller(Marshaller marshaller) {
Assert.notNull(marshaller, "'marshaller' must not be null");
this.marshaller = marshaller;
}
/**
* Set the name of the model key that represents the object to be marshalled. If not specified, the model map will be
* searched for a supported value type.
*
* @see Marshaller#supports(Class)
*/
public void setModelKey(String modelKey) {
this.modelKey = modelKey;
}
@Override
protected void initApplicationContext() throws BeansException {
Assert.notNull(marshaller, "Property 'marshaller' is required");
}
@Override
protected void renderMergedOutputModel(Map model, HttpServletRequest request, HttpServletResponse response)
throws Exception {
Object toBeMarshalled = locateToBeMarshalled(model);
if (toBeMarshalled == null) {
throw new ServletException("Unable to locate object to be marshalled in model: " + model);
}
ByteArrayOutputStream bos = new ByteArrayOutputStream(2048);
marshaller.marshal(toBeMarshalled, new StreamResult(bos));
response.setContentType(getContentType());
response.setContentLength(bos.size());
FileCopyUtils.copy(bos.toByteArray(), response.getOutputStream());
}
/**
* Locates the object to be marshalled. The default implementation first attempts to look under the configured
* {@linkplain #setModelKey(String) model key}, if any, before attempting to locate an object of {@linkplain
* Marshaller#supports(Class) supported type}.
*
* @param model the model Map
* @return the Object to be marshalled (or <code>null</code> if none found)
* @throws ServletException if the model object specified by the {@linkplain #setModelKey(String) model key} is not
* supported by the marshaller
* @see #setModelKey(String)
*/
protected Object locateToBeMarshalled(Map model) throws ServletException {
if (this.modelKey != null) {
Object o = model.get(this.modelKey);
if (o == null) {
throw new ServletException("Model contains no object with key [" + modelKey + "]");
}
if (!this.marshaller.supports(o.getClass())) {
throw new ServletException("Model object [" + o + "] retrieved via key [" + modelKey +
"] is not supported by the Marshaller");
}
return o;
}
for (Object o : model.values()) {
if (o != null && this.marshaller.supports(o.getClass())) {
return o;
}
}
return null;
}
}
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