Add ContentNegotiationManagerFactoryBean

The new FactoryBean facilitates the creation of a
ContentNegotiationManager in XML configuration.

Issue: SPR-8420

spring-web/src/main/java/org/springframework/web/accept/ContentNegotiationManagerFactoryBean.java

@@ -0,0 +1,185 @@
+/*
+ * Copyright 2002-2012 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.accept;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Properties;
+
+import javax.servlet.ServletContext;
+
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.http.MediaType;
+import org.springframework.util.CollectionUtils;
+
+/**
+ * A factory providing convenient access to a {@code ContentNegotiationManager}
+ * configured with one or more {@link ContentNegotiationStrategy} instances.
+ *
+ * <p>By default strategies for checking the extension of the request path and
+ * the {@code Accept} header are registered. The path extension check will perform
+ * lookups through the {@link ServletContext} and the Java Activation Framework
+ * (if present) unless {@linkplain #setMediaTypes(Map) media types} are configured.
+ *
+ * @author Rossen Stoyanchev
+ * @since 3.2
+ */
+public class ContentNegotiationManagerFactoryBean implements FactoryBean<ContentNegotiationManager>, InitializingBean {
+
+	private boolean favorPathExtension = true;
+
+	private boolean favorParameter = false;
+
+	private boolean ignoreAcceptHeader = false;
+
+	private Map<String, MediaType> mediaTypes = new HashMap<String, MediaType>();
+
+	private Boolean useJaf;
+
+	private String parameterName;
+
+	private MediaType defaultContentType;
+
+	private ContentNegotiationManager contentNegotiationManager;
+
+	/**
+	 * Indicate whether the extension of the request path should be used to determine
+	 * the requested media type with the <em>highest priority</em>.
+	 * <p>By default this value is set to {@code true} in which case a request
+	 * for {@code /hotels.pdf} will be interpreted as a request for
+	 * {@code "application/pdf"} regardless of the {@code Accept} header.
+	 */
+	public void setFavorPathExtension(boolean favorPathExtension) {
+		this.favorPathExtension = favorPathExtension;
+	}
+
+	/**
+	 * Add mappings from file extensions to media types.
+	 * <p>If this property is not set, the Java Action Framework, if available, may
+	 * still be used in conjunction with {@link #setFavorPathExtension(boolean)}.
+	 */
+	public void setMediaTypes(Properties mediaTypes) {
+		if (!CollectionUtils.isEmpty(mediaTypes)) {
+			for (Map.Entry<Object, Object> entry : mediaTypes.entrySet()) {
+				String extension = ((String) entry.getKey()).toLowerCase(Locale.ENGLISH);
+				this.mediaTypes.put(extension, MediaType.valueOf((String) entry.getValue()));
+			}
+		}
+	}
+
+	/**
+	 * Indicate whether to use the Java Activation Framework as a fallback option
+	 * to map from file extensions to media types. This is used only when
+	 * {@link #setFavorPathExtension(boolean)} is set to {@code true}.
+	 * <p>The default value is {@code true}.
+	 * @see #parameterName
+	 * @see #setMediaTypes(Map)
+	 */
+	public void setUseJaf(boolean useJaf) {
+		this.useJaf = useJaf;
+	}
+
+	/**
+	 * Indicate whether a request parameter should be used to determine the
+	 * requested media type with the <em>2nd highest priority</em>, i.e.
+	 * after path extensions but before the {@code Accept} header.
+	 * <p>The default value is {@code false}. If set to to {@code true}, a request
+	 * for {@code /hotels?format=pdf} will be interpreted as a request for
+	 * {@code "application/pdf"} regardless of the {@code Accept} header.
+	 * <p>To use this option effectively you must also configure the MediaType
+	 * type mappings via {@link #setMediaTypes(Map)}.
+	 * @see #setParameterName(String)
+	 */
+	public void setFavorParameter(boolean favorParameter) {
+		this.favorParameter = favorParameter;
+	}
+
+	/**
+	 * Set the parameter name that can be used to determine the requested media type
+	 * if the {@link #setFavorParameter} property is {@code true}.
+	 * <p>The default parameter name is {@code "format"}.
+	 */
+	public void setParameterName(String parameterName) {
+		this.parameterName = parameterName;
+	}
+
+	/**
+	 * Indicate whether the HTTP {@code Accept} header should be ignored altogether.
+	 * If set the {@code Accept} header is checked at the
+	 * <em>3rd highest priority</em>, i.e. after the request path extension and
+	 * possibly a request parameter if configured.
+	 * <p>By default this value is set to {@code false}.
+	 */
+	public void setIgnoreAcceptHeader(boolean ignoreAcceptHeader) {
+		this.ignoreAcceptHeader = ignoreAcceptHeader;
+	}
+
+	/**
+	 * Set the default content type.
+	 * <p>This content type will be used when neither the request path extension,
+	 * nor a request parameter, nor the {@code Accept} header could help determine
+	 * the requested content type.
+	 */
+	public void setDefaultContentType(MediaType defaultContentType) {
+		this.defaultContentType = defaultContentType;
+	}
+
+	public void afterPropertiesSet() throws Exception {
+		List<ContentNegotiationStrategy> strategies = new ArrayList<ContentNegotiationStrategy>();
+
+		if (this.favorPathExtension) {
+			PathExtensionContentNegotiationStrategy strategy = new PathExtensionContentNegotiationStrategy(this.mediaTypes);
+			if (this.useJaf != null) {
+				strategy.setUseJaf(this.useJaf);
+			}
+			strategies.add(strategy);
+		}
+
+		if (this.favorParameter) {
+			ParameterContentNegotiationStrategy strategy = new ParameterContentNegotiationStrategy(this.mediaTypes);
+			strategy.setParameterName(this.parameterName);
+			strategies.add(strategy);
+		}
+
+		if (!this.ignoreAcceptHeader) {
+			strategies.add(new HeaderContentNegotiationStrategy());
+		}
+
+		if (this.defaultContentType != null) {
+			strategies.add(new FixedContentNegotiationStrategy(this.defaultContentType));
+		}
+
+		ContentNegotiationStrategy[] array = strategies.toArray(new ContentNegotiationStrategy[strategies.size()]);
+		this.contentNegotiationManager = new ContentNegotiationManager(array);
+	}
+
+	public Class<?> getObjectType() {
+		return ContentNegotiationManager.class;
+	}
+
+	public boolean isSingleton() {
+		return true;
+	}
+
+	public ContentNegotiationManager getObject() throws Exception {
+		return this.contentNegotiationManager;
+	}
+
+}