Add FreeMarker View, ViewResolver and basic hierarchy

spring-web-reactive/build.gradle

@@ -84,6 +84,7 @@ dependencies {
 	compile "io.projectreactor:reactor-core:${reactorVersion}"
 	compile "commons-logging:commons-logging:1.2"
 
+	optional "org.springframework:spring-context-support:${springVersion}" // for FreeMarker
 	optional 'io.reactivex:rxjava:1.1.0'
 	optional "io.reactivex:rxnetty-http:0.5.0-SNAPSHOT"
 	optional "com.fasterxml.jackson.core:jackson-databind:2.6.2"
@@ -95,6 +96,7 @@ dependencies {
 	optional 'io.undertow:undertow-core:1.3.5.Final'
 	optional "org.eclipse.jetty:jetty-server:${jettyVersion}"
 	optional "org.eclipse.jetty:jetty-servlet:${jettyVersion}"
+	optional("org.freemarker:freemarker:2.3.23")
 
 	provided "javax.servlet:javax.servlet-api:3.1.0"
 

spring-web-reactive/src/main/java/org/springframework/web/reactive/method/annotation/ResponseBodyResultHandler.java

@@ -66,7 +66,7 @@ public class ResponseBodyResultHandler implements HandlerResultHandler, Ordered
 
 	private final Map<Encoder<?>, List<MediaType>> mediaTypesByEncoder;
 
-	private int order = 0;
+	private int order = 0; // TODO: should be MAX_VALUE
 
 
 	public ResponseBodyResultHandler(List<Encoder<?>> encoders, ConversionService service) {

spring-web-reactive/src/main/java/org/springframework/web/reactive/view/AbstractUrlBasedView.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2002-2016 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.reactive.view;
+
+import java.util.Locale;
+
+import org.springframework.beans.factory.InitializingBean;
+
+/**
+ * Abstract base class for URL-based views. Provides a consistent way of
+ * holding the URL that a View wraps, in the form of a "url" bean property.
+ *
+ * @author Rossen Stoyanchev
+ */
+public abstract class AbstractUrlBasedView extends AbstractView implements InitializingBean {
+
+	private String url;
+
+
+	/**
+	 * Constructor for use as a bean.
+	 */
+	protected AbstractUrlBasedView() {
+	}
+
+	/**
+	 * Create a new AbstractUrlBasedView with the given URL.
+	 */
+	protected AbstractUrlBasedView(String url) {
+		this.url = url;
+	}
+
+
+	/**
+	 * Set the URL of the resource that this view wraps.
+	 * The URL must be appropriate for the concrete View implementation.
+	 */
+	public void setUrl(String url) {
+		this.url = url;
+	}
+
+	/**
+	 * Return the URL of the resource that this view wraps.
+	 */
+	public String getUrl() {
+		return this.url;
+	}
+
+
+	@Override
+	public void afterPropertiesSet() throws Exception {
+		if (getUrl() == null) {
+			throw new IllegalArgumentException("Property 'url' is required");
+		}
+	}
+
+	/**
+	 * Check whether the resource for the configured URL actually exists.
+	 * @param locale the desired Locale that we're looking for
+	 * @return {@code false} if the resource exists
+	 * {@code false} if we know that it does not exist
+	 * @throws Exception if the resource exists but is invalid (e.g. could not be parsed)
+	 */
+	public abstract boolean checkResourceExists(Locale locale) throws Exception;
+
+
+	@Override
+	public String toString() {
+		return super.toString() + "; URL [" + getUrl() + "]";
+	}
+
+}

spring-web-reactive/src/main/java/org/springframework/web/reactive/view/AbstractView.java

@@ -0,0 +1,166 @@
+/*
+ * Copyright 2002-2016 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.reactive.view;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import reactor.core.publisher.Flux;
+
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
+import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.core.io.buffer.DataBufferAllocator;
+import org.springframework.core.io.buffer.DefaultDataBufferAllocator;
+import org.springframework.http.MediaType;
+import org.springframework.ui.ModelMap;
+import org.springframework.util.Assert;
+import org.springframework.web.reactive.HandlerResult;
+import org.springframework.web.reactive.View;
+import org.springframework.web.server.ServerWebExchange;
+
+/**
+ *
+ * @author Rossen Stoyanchev
+ */
+public abstract class AbstractView implements View, ApplicationContextAware {
+
+	/** Logger that is available to subclasses */
+	protected final Log logger = LogFactory.getLog(getClass());
+
+
+	private final List<MediaType> mediaTypes = new ArrayList<>(4);
+
+	private DataBufferAllocator bufferAllocator = new DefaultDataBufferAllocator();
+
+	private ApplicationContext applicationContext;
+
+
+	public AbstractView() {
+		this.mediaTypes.add(ViewResolverSupport.DEFAULT_CONTENT_TYPE);
+	}
+
+
+	/**
+	 * Set the supported media types for this view.
+	 * Default is "text/html;charset=UTF-8".
+	 */
+	public void setSupportedMediaTypes(List<MediaType> supportedMediaTypes) {
+		Assert.notEmpty(supportedMediaTypes, "'supportedMediaTypes' is required.");
+		this.mediaTypes.clear();
+		if (supportedMediaTypes != null) {
+			this.mediaTypes.addAll(supportedMediaTypes);
+		}
+	}
+
+	/**
+	 * Return the configured media types supported by this view.
+	 */
+	@Override
+	public List<MediaType> getSupportedMediaTypes() {
+		return this.mediaTypes;
+	}
+
+	/**
+	 * Configure the {@link DataBufferAllocator} to use for write I/O.
+	 * <p>By default this is set to {@link DefaultDataBufferAllocator}.
+	 * @param bufferAllocator the allocator to use
+	 */
+	public void setBufferAllocator(DataBufferAllocator bufferAllocator) {
+		Assert.notNull(bufferAllocator, "'bufferAllocator' is required.");
+		this.bufferAllocator = bufferAllocator;
+	}
+
+	/**
+	 * Return the configured buffer allocator, never {@code null}.
+	 */
+	public DataBufferAllocator getBufferAllocator() {
+		return this.bufferAllocator;
+	}
+
+	@Override
+	public void setApplicationContext(ApplicationContext applicationContext) {
+		this.applicationContext = applicationContext;
+	}
+
+	public ApplicationContext getApplicationContext() {
+		return applicationContext;
+	}
+
+
+	/**
+	 * Prepare the model to render.
+	 * @param result the result from handler execution
+	 * @param contentType the content type selected to render with which should
+	 * match one of the {@link #getSupportedMediaTypes() supported media types}.
+	 * @param exchange the current exchange
+	 * @return
+	 */
+	@Override
+	public Flux<DataBuffer> render(HandlerResult result, Optional<MediaType> contentType,
+			ServerWebExchange exchange) {
+
+		if (logger.isTraceEnabled()) {
+			logger.trace("Rendering view with model " + result.getModel());
+		}
+
+		if (contentType.isPresent()) {
+			exchange.getResponse().getHeaders().setContentType(contentType.get());
+		}
+
+		Map<String, Object> mergedModel = getModelAttributes(result, exchange);
+		return renderInternal(mergedModel, exchange);
+	}
+
+	/**
+	 * Prepare the model to use for rendering.
+	 * <p>The default implementation creates a combined output Map that includes
+	 * model as well as static attributes with the former taking precedence.
+	 */
+	protected Map<String, Object> getModelAttributes(HandlerResult result, ServerWebExchange exchange) {
+		ModelMap model = result.getModel();
+		int size = (model != null ? model.size() : 0);
+
+		Map<String, Object> attributes = new LinkedHashMap<>(size);
+		if (model != null) {
+			attributes.putAll(model);
+		}
+
+		return attributes;
+	}
+
+	/**
+	 * Subclasses must implement this method to actually render the view.
+	 * @param renderAttributes combined output Map (never {@code null}),
+	 * with dynamic values taking precedence over static attributes
+	 * @param exchange current exchange
+	 */
+	protected abstract Flux<DataBuffer> renderInternal(Map<String, Object> renderAttributes,
+			ServerWebExchange exchange);
+
+
+	@Override
+	public String toString() {
+		return getClass().getName();
+	}
+
+}

spring-web-reactive/src/main/java/org/springframework/web/reactive/view/UrlBasedViewResolver.java

@@ -0,0 +1,168 @@
+/*
+ * Copyright 2002-2016 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.reactive.view;
+
+import java.util.Locale;
+
+import reactor.core.publisher.Mono;
+
+import org.springframework.beans.BeanUtils;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.web.reactive.View;
+
+
+/**
+ * A {@link org.springframework.web.reactive.ViewResolver ViewResolver} that
+ * allow direct resolution of symbolic view names to URLs without explicit
+ * mapping definition. This is useful if symbolic names match the names of view
+ * resources in a straightforward manner (i.e. the symbolic name is the unique
+ * part of the resource's filename), without the need for a dedicated mapping
+ * to be defined for each view.
+ *
+ * <p>Supports {@link AbstractUrlBasedView} subclasses like
+ * {@link org.springframework.web.reactive.view.freemarker.FreeMarkerView}.
+ * The view class for all views generated by this resolver can be specified
+ * via the "viewClass" property.
+ *
+ * <p>View names can either be resource URLs themselves, or get augmented by a
+ * specified prefix and/or suffix. Exporting an attribute that holds the
+ * RequestContext to all views is explicitly supported.
+ *
+ * <p>Example: prefix="templates/", suffix=".ftl", viewname="test" ->
+ * "templates/test.ftl"
+ *
+ * <p>As a special feature, redirect URLs can be specified via the "redirect:"
+ * prefix. E.g.: "redirect:myAction" will trigger a redirect to the given
+ * URL, rather than resolution as standard view name. This is typically used
+ * for redirecting to a controller URL after finishing a form workflow.
+ *
+ * <p>Note: This class does not support localized resolution, i.e. resolving
+ * a symbolic view name to different resources depending on the current locale.
+ * * @author Rossen Stoyanchev
+ */
+public class UrlBasedViewResolver extends ViewResolverSupport implements InitializingBean {
+
+	private Class<?> viewClass;
+
+	private String prefix = "";
+
+	private String suffix = "";
+
+
+	/**
+	 * Set the view class to instantiate through {@link #createUrlBasedView(String)}.
+	 * @param viewClass a class that is assignable to the required view class
+	 * which by default is AbstractUrlBasedView.
+	 */
+	public void setViewClass(Class<?> viewClass) {
+		if (viewClass == null || !requiredViewClass().isAssignableFrom(viewClass)) {
+			String name = (viewClass != null ? viewClass.getName() : null);
+			throw new IllegalArgumentException("Given view class [" + name + "] " +
+					"is not of type [" + requiredViewClass().getName() + "]");
+		}
+		this.viewClass = viewClass;
+	}
+
+	/**
+	 * Return the view class to be used to create views.
+	 */
+	protected Class<?> getViewClass() {
+		return this.viewClass;
+	}
+
+	/**
+	 * Return the required type of view for this resolver.
+	 * This implementation returns {@link AbstractUrlBasedView}.
+	 * @see AbstractUrlBasedView
+	 */
+	protected Class<?> requiredViewClass() {
+		return AbstractUrlBasedView.class;
+	}
+
+	/**
+	 * Set the prefix that gets prepended to view names when building a URL.
+	 */
+	public void setPrefix(String prefix) {
+		this.prefix = (prefix != null ? prefix : "");
+	}
+
+	/**
+	 * Return the prefix that gets prepended to view names when building a URL.
+	 */
+	protected String getPrefix() {
+		return this.prefix;
+	}
+
+	/**
+	 * Set the suffix that gets appended to view names when building a URL.
+	 */
+	public void setSuffix(String suffix) {
+		this.suffix = (suffix != null ? suffix : "");
+	}
+
+	/**
+	 * Return the suffix that gets appended to view names when building a URL.
+	 */
+	protected String getSuffix() {
+		return this.suffix;
+	}
+
+
+	@Override
+	public void afterPropertiesSet() throws Exception {
+		if (getViewClass() == null) {
+			throw new IllegalArgumentException("Property 'viewClass' is required");
+		}
+	}
+
+
+	@Override
+	public Mono<View> resolveViewName(String viewName, Locale locale) {
+		AbstractUrlBasedView urlBasedView = createUrlBasedView(viewName);
+		View view = applyLifecycleMethods(viewName, urlBasedView);
+		try {
+			return (urlBasedView.checkResourceExists(locale) ? Mono.just(view) : Mono.empty());
+		}
+		catch (Exception ex) {
+			return Mono.error(ex);
+		}
+	}
+
+	/**
+	 * Creates a new View instance of the specified view class and configures it.
+	 * Does <i>not</i> perform any lookup for pre-defined View instances.
+	 * <p>Spring lifecycle methods as defined by the bean container do not have to
+	 * be called here; those will be applied by the {@code loadView} method
+	 * after this method returns.
+	 * <p>Subclasses will typically call {@code super.buildView(viewName)}
+	 * first, before setting further properties themselves. {@code loadView}
+	 * will then apply Spring lifecycle methods at the end of this process.
+	 * @param viewName the name of the view to build
+	 * @return the View instance
+	 */
+	protected AbstractUrlBasedView createUrlBasedView(String viewName) {
+		AbstractUrlBasedView view = (AbstractUrlBasedView) BeanUtils.instantiateClass(getViewClass());
+		view.setSupportedMediaTypes(getSupportedMediaTypes());
+		view.setBufferAllocator(getBufferAllocator());
+		view.setUrl(getPrefix() + viewName + getSuffix());
+		return view;
+	}
+
+	private View applyLifecycleMethods(String viewName, AbstractView view) {
+		return (View) getApplicationContext().getAutowireCapableBeanFactory().initializeBean(view, viewName);
+	}
+
+}

spring-web-reactive/src/main/java/org/springframework/web/reactive/view/ViewResolverResultHandler.java

@@ -24,6 +24,7 @@ import java.util.Optional;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
+import org.springframework.core.Ordered;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.util.Assert;
@@ -45,12 +46,14 @@ import org.springframework.web.server.ServerWebExchange;
  *
  * @author Rossen Stoyanchev
  */
-public class ViewResolverResultHandler implements HandlerResultHandler {
+public class ViewResolverResultHandler implements HandlerResultHandler, Ordered {
 
 	private final List<ViewResolver> viewResolvers = new ArrayList<>(4);
 
 	private final ConversionService conversionService;
 
+	private int order = Integer.MAX_VALUE;
+
 
 	public ViewResolverResultHandler(List<ViewResolver> resolvers, ConversionService service) {
 		Assert.notEmpty(resolvers, "At least one ViewResolver is required.");
@@ -67,6 +70,15 @@ public class ViewResolverResultHandler implements HandlerResultHandler {
 		return Collections.unmodifiableList(this.viewResolvers);
 	}
 
+	public void setOrder(int order) {
+		this.order = order;
+	}
+
+	@Override
+	public int getOrder() {
+		return this.order;
+	}
+
 
 	// TODO: @ModelAttribute return value, declared Object return value (either String or View)
 

spring-web-reactive/src/main/java/org/springframework/web/reactive/view/ViewResolverSupport.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright 2002-2016 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.reactive.view;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
+import org.springframework.core.Ordered;
+import org.springframework.core.io.buffer.DataBufferAllocator;
+import org.springframework.core.io.buffer.DefaultDataBufferAllocator;
+import org.springframework.http.MediaType;
+import org.springframework.util.Assert;
+import org.springframework.web.reactive.ViewResolver;
+
+/**
+ * Base class for {@code ViewResolver} implementations with shared properties.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.3
+ */
+public abstract class ViewResolverSupport implements ViewResolver, ApplicationContextAware, Ordered {
+
+	public static final MediaType DEFAULT_CONTENT_TYPE = MediaType.parseMediaType("text/html;charset=UTF-8");
+
+
+	private List<MediaType> mediaTypes = new ArrayList<>(4);
+
+	private DataBufferAllocator bufferAllocator = new DefaultDataBufferAllocator();
+
+	private ApplicationContext applicationContext;
+
+	private int order = Integer.MAX_VALUE;
+
+
+	public ViewResolverSupport() {
+		this.mediaTypes.add(DEFAULT_CONTENT_TYPE);
+	}
+
+
+	/**
+	 * Set the supported media types for this view.
+	 * Default is "text/html;charset=UTF-8".
+	 */
+	public void setSupportedMediaTypes(List<MediaType> supportedMediaTypes) {
+		Assert.notEmpty(supportedMediaTypes, "'supportedMediaTypes' is required.");
+		this.mediaTypes.clear();
+		if (supportedMediaTypes != null) {
+			this.mediaTypes.addAll(supportedMediaTypes);
+		}
+	}
+
+	/**
+	 * Return the configured media types supported by this view.
+	 */
+	public List<MediaType> getSupportedMediaTypes() {
+		return this.mediaTypes;
+	}
+
+	/**
+	 * Configure the {@link DataBufferAllocator} to use for write I/O.
+	 * <p>By default this is set to {@link DefaultDataBufferAllocator}.
+	 * @param bufferAllocator the allocator to use
+	 */
+	public void setBufferAllocator(DataBufferAllocator bufferAllocator) {
+		Assert.notNull(bufferAllocator, "'bufferAllocator' is required.");
+		this.bufferAllocator = bufferAllocator;
+	}
+
+	/**
+	 * Return the configured buffer allocator, never {@code null}.
+	 */
+	public DataBufferAllocator getBufferAllocator() {
+		return this.bufferAllocator;
+	}
+
+	@Override
+	public void setApplicationContext(ApplicationContext applicationContext) {
+		this.applicationContext = applicationContext;
+	}
+
+	public ApplicationContext getApplicationContext() {
+		return this.applicationContext;
+	}
+
+	/**
+	 * Set the order in which this {@link ViewResolver}
+	 * is evaluated.
+	 */
+	public void setOrder(int order) {
+		this.order = order;
+	}
+
+	/**
+	 * Return the order in which this {@link ViewResolver} is evaluated.
+	 */
+	@Override
+	public int getOrder() {
+		return this.order;
+	}
+
+}

spring-web-reactive/src/main/java/org/springframework/web/reactive/view/freemarker/FreeMarkerConfig.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2002-2016 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.reactive.view.freemarker;
+
+import freemarker.template.Configuration;
+
+/**
+ * Interface to be implemented by objects that configure and manage a
+ * FreeMarker Configuration object in a web environment. Detected and
+ * used by {@link FreeMarkerView}.
+ *
+ * @author Rossen Stoyanchev
+ */
+public interface FreeMarkerConfig {
+
+	/**
+	 * Return the FreeMarker Configuration object for the current
+	 * web application context.
+	 * <p>A FreeMarker Configuration object may be used to set FreeMarker
+	 * properties and shared objects, and allows to retrieve templates.
+	 * @return the FreeMarker Configuration
+	 */
+	Configuration getConfiguration();
+
+}

spring-web-reactive/src/main/java/org/springframework/web/reactive/view/freemarker/FreeMarkerConfigurer.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright 2002-2016 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.reactive.view.freemarker;
+
+import java.io.IOException;
+import java.util.List;
+
+import freemarker.cache.ClassTemplateLoader;
+import freemarker.cache.TemplateLoader;
+import freemarker.template.Configuration;
+import freemarker.template.TemplateException;
+
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.context.ResourceLoaderAware;
+import org.springframework.ui.freemarker.FreeMarkerConfigurationFactory;
+
+/**
+ * Configures FreeMarker for web usage via the "configLocation" and/or
+ * "freemarkerSettings" and/or "templateLoaderPath" properties.
+ * The simplest way to use this class is to specify just a "templateLoaderPath"
+ * (e.g. "classpath:templates"); you do not need any further configuration then.
+ *
+ * <p>This bean must be included in the application context of any application
+ * using {@link FreeMarkerView}. It exists purely to configure FreeMarker.
+ * It is not meant to be referenced by application components but just internally
+ * by {@code FreeMarkerView}. Implements {@link FreeMarkerConfig} to be found by
+ * {@code FreeMarkerView} without depending on the bean name the configurer.
+ *
+ * <p>Note that you can also refer to a pre-configured FreeMarker Configuration
+ * instance via the "configuration" property. This allows to share a FreeMarker
+ * Configuration for web and email usage for example.
+ *
+ * <p>TODO: macros
+ *
+ * <p>This configurer registers a template loader for this package, allowing to
+ * reference the "spring.ftl" macro library contained in this package:
+ *
+ * <pre class="code">
+ * &lt;#import "/spring.ftl" as spring/&gt;
+ * &lt;@spring.bind "person.age"/&gt;
+ * age is ${spring.status.value}</pre>
+ *
+ * Note: Spring's FreeMarker support requires FreeMarker 2.3 or higher.
+ *
+ * @author Rossen Stoyanchev
+ */
+public class FreeMarkerConfigurer extends FreeMarkerConfigurationFactory
+		implements FreeMarkerConfig, InitializingBean, ResourceLoaderAware {
+
+	private Configuration configuration;
+
+
+	public FreeMarkerConfigurer() {
+		setDefaultEncoding("UTF-8");
+	}
+
+
+	/**
+	 * Set a pre-configured Configuration to use for the FreeMarker web config,
+	 * e.g. a shared one for web and email usage. If this is not set,
+	 * FreeMarkerConfigurationFactory's properties (inherited by this class)
+	 * have to be specified.
+	 */
+	public void setConfiguration(Configuration configuration) {
+		this.configuration = configuration;
+	}
+
+
+	/**
+	 * Initialize FreeMarkerConfigurationFactory's Configuration
+	 * if not overridden by a pre-configured FreeMarker Configuation.
+	 * <p>Sets up a ClassTemplateLoader to use for loading Spring macros.
+	 * @see #createConfiguration
+	 * @see #setConfiguration
+	 */
+	@Override
+	public void afterPropertiesSet() throws IOException, TemplateException {
+		if (this.configuration == null) {
+			this.configuration = createConfiguration();
+		}
+	}
+
+	/**
+	 * This implementation registers an additional ClassTemplateLoader
+	 * for the Spring-provided macros, added to the end of the list.
+	 */
+	@Override
+	protected void postProcessTemplateLoaders(List<TemplateLoader> templateLoaders) {
+		templateLoaders.add(new ClassTemplateLoader(FreeMarkerConfigurer.class, ""));
+		logger.info("ClassTemplateLoader for Spring macros added to FreeMarker configuration");
+	}
+
+
+	/**
+	 * Return the Configuration object wrapped by this bean.
+	 */
+	@Override
+	public Configuration getConfiguration() {
+		return this.configuration;
+	}
+
+}

spring-web-reactive/src/main/java/org/springframework/web/reactive/view/freemarker/FreeMarkerView.java

@@ -0,0 +1,219 @@
+/*
+ * Copyright 2002-2016 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.reactive.view.freemarker;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.util.Locale;
+import java.util.Map;
+
+import freemarker.core.ParseException;
+import freemarker.template.Configuration;
+import freemarker.template.DefaultObjectWrapperBuilder;
+import freemarker.template.ObjectWrapper;
+import freemarker.template.SimpleHash;
+import freemarker.template.Template;
+import freemarker.template.Version;
+import reactor.core.publisher.Flux;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.BeanFactoryUtils;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.context.ApplicationContextException;
+import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.web.reactive.view.AbstractUrlBasedView;
+import org.springframework.web.server.ServerWebExchange;
+
+/**
+ * A {@code View} implementation that uses the FreeMarker template engine.
+ *
+ * <p>Depends on a single {@link FreeMarkerConfig} object such as
+ * {@link FreeMarkerConfigurer} being accessible in the application context.
+ * Alternatively set the FreeMarker configuration can be set directly on this
+ * class via {@link #setConfiguration}.
+ *
+ * <p>The {@link #setUrl(String) url} property is the location of the FreeMarker
+ * template relative to the FreeMarkerConfigurer's
+ * {@link FreeMarkerConfigurer#setTemplateLoaderPath templateLoaderPath}.
+ *
+ * <p>Note: Spring's FreeMarker support requires FreeMarker 2.3 or higher.
+ *
+ * @author Rossen Stoyanchev
+ */
+public class FreeMarkerView extends AbstractUrlBasedView {
+
+	private Configuration configuration;
+
+	private String encoding;
+
+
+	/**
+	 * Set the FreeMarker Configuration to be used by this view.
+	 * <p>Typically this property is not set directly. Instead a single
+	 * {@link FreeMarkerConfig} is expected in the Spring application context
+	 * which is used to obtain the FreeMarker configuration.
+	 */
+	public void setConfiguration(Configuration configuration) {
+		this.configuration = configuration;
+	}
+
+	/**
+	 * Return the FreeMarker configuration used by this view.
+	 */
+	protected Configuration getConfiguration() {
+		return this.configuration;
+	}
+
+	/**
+	 * Set the encoding of the FreeMarker template file.
+	 * <p>By default {@link FreeMarkerConfigurer} sets the default encoding in
+	 * the FreeMarker configuration to "UTF-8". It's recommended to specify the
+	 * encoding in the FreeMarker Configuration rather than per template if all
+	 * your templates share a common encoding.
+	 */
+	public void setEncoding(String encoding) {
+		this.encoding = encoding;
+	}
+
+	/**
+	 * Return the encoding for the FreeMarker template.
+	 */
+	protected String getEncoding() {
+		return this.encoding;
+	}
+
+
+	@Override
+	public void afterPropertiesSet() throws Exception {
+		super.afterPropertiesSet();
+		if (getConfiguration() == null) {
+			FreeMarkerConfig config = autodetectConfiguration();
+			setConfiguration(config.getConfiguration());
+		}
+	}
+
+	/**
+	 * Autodetect a {@link FreeMarkerConfig} object via the ApplicationContext.
+	 * @return the Configuration instance to use for FreeMarkerViews
+	 * @throws BeansException if no Configuration instance could be found
+	 * @see #setConfiguration
+	 */
+	protected FreeMarkerConfig autodetectConfiguration() throws BeansException {
+		try {
+			return BeanFactoryUtils.beanOfTypeIncludingAncestors(
+					getApplicationContext(), FreeMarkerConfig.class, true, false);
+		}
+		catch (NoSuchBeanDefinitionException ex) {
+			throw new ApplicationContextException(
+					"Must define a single FreeMarkerConfig bean in this web application context " +
+							"(may be inherited): FreeMarkerConfigurer is the usual implementation. " +
+							"This bean may be given any name.", ex);
+		}
+	}
+
+
+	/**
+	 * Check that the FreeMarker template used for this view exists and is valid.
+	 * <p>Can be overridden to customize the behavior, for example in case of
+	 * multiple templates to be rendered into a single view.
+	 */
+	@Override
+	public boolean checkResourceExists(Locale locale) throws Exception {
+		try {
+			// Check that we can get the template, even if we might subsequently get it again.
+			getTemplate(locale);
+			return true;
+		}
+		catch (FileNotFoundException ex) {
+			if (logger.isDebugEnabled()) {
+				logger.debug("No FreeMarker view found for URL: " + getUrl());
+			}
+			return false;
+		}
+		catch (ParseException ex) {
+			throw new ApplicationContextException(
+					"Failed to parse FreeMarker template for URL [" +  getUrl() + "]", ex);
+		}
+		catch (IOException ex) {
+			throw new ApplicationContextException(
+					"Could not load FreeMarker template for URL [" + getUrl() + "]", ex);
+		}
+	}
+
+	@Override
+	protected Flux<DataBuffer> renderInternal(Map<String, Object> renderAttributes, ServerWebExchange exchange) {
+		// Expose all standard FreeMarker hash models.
+		SimpleHash freeMarkerModel = getTemplateModel(renderAttributes, exchange);
+		if (logger.isDebugEnabled()) {
+			logger.debug("Rendering FreeMarker template [" + getUrl() + "].");
+		}
+		Locale locale = Locale.getDefault(); // TODO
+		DataBuffer dataBuffer = getBufferAllocator().allocateBuffer();
+		try {
+			Writer writer = new OutputStreamWriter(dataBuffer.asOutputStream());
+			getTemplate(locale).process(freeMarkerModel, writer);
+		}
+		catch (IOException ex) {
+			String message = "Could not load FreeMarker template for URL [" + getUrl() + "]";
+			return Flux.error(new IllegalStateException(message, ex));
+		}
+		catch (Throwable ex) {
+			return Flux.error(ex);
+		}
+		return Flux.just(dataBuffer);
+	}
+
+	/**
+	 * Build a FreeMarker template model for the given model Map.
+	 * <p>The default implementation builds a {@link SimpleHash}.
+	 * @param model the model to use for rendering
+	 * @param exchange current exchange
+	 * @return the FreeMarker template model, as a {@link SimpleHash} or subclass thereof
+	 */
+	protected SimpleHash getTemplateModel(Map<String, Object> model, ServerWebExchange exchange) {
+		SimpleHash fmModel = new SimpleHash(getObjectWrapper());
+		fmModel.putAll(model);
+		return fmModel;
+	}
+
+	/**
+	 * Return the configured FreeMarker {@link ObjectWrapper}, or the
+	 * {@link ObjectWrapper#DEFAULT_WRAPPER default wrapper} if none specified.
+	 * @see freemarker.template.Configuration#getObjectWrapper()
+	 */
+	protected ObjectWrapper getObjectWrapper() {
+		ObjectWrapper ow = getConfiguration().getObjectWrapper();
+		Version version = Configuration.DEFAULT_INCOMPATIBLE_IMPROVEMENTS;
+		return (ow != null ? ow : new DefaultObjectWrapperBuilder(version).build());
+	}
+
+	/**
+	 * Retrieve the FreeMarker template for the given locale,
+	 * to be rendering by this view.
+	 * <p>By default, the template specified by the "url" bean property
+	 * will be retrieved.
+	 * @param locale the current locale
+	 * @return the FreeMarker template to render
+	 */
+	protected Template getTemplate(Locale locale) throws IOException {
+		return (getEncoding() != null ?
+				getConfiguration().getTemplate(getUrl(), locale, getEncoding()) :
+				getConfiguration().getTemplate(getUrl(), locale));
+	}
+
+}

spring-web-reactive/src/main/java/org/springframework/web/reactive/view/freemarker/FreeMarkerViewResolver.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2002-2016 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.reactive.view.freemarker;
+
+import org.springframework.web.reactive.view.UrlBasedViewResolver;
+
+/**
+ * A {@code ViewResolver} for resolving {@link FreeMarkerView} instances, i.e.
+ * FreeMarker templates and custom subclasses of it.
+ *
+ * <p>The view class for all views generated by this resolver can be specified
+ * via the "viewClass" property. See {@link UrlBasedViewResolver} for details.
+ *
+ * @author Rossen Stoyanchev
+ */public class FreeMarkerViewResolver extends UrlBasedViewResolver {
+
+
+	/**
+	 * Simple constructor.
+	 */
+	public FreeMarkerViewResolver() {
+		setViewClass(requiredViewClass());
+	}
+
+	/**
+	 * Convenience constructor with a prefix and suffix.
+	 * @param suffix the suffix to prepend view names with
+	 * @param prefix the prefix to prepend view names with
+	 */
+	public FreeMarkerViewResolver(String prefix, String suffix) {
+		setViewClass(requiredViewClass());
+		setPrefix(prefix);
+		setSuffix(suffix);
+	}
+
+
+	/**
+	 * Requires {@link FreeMarkerView}.
+	 */
+	@Override
+	protected Class<?> requiredViewClass() {
+		return FreeMarkerView.class;
+	}
+
+}

spring-web-reactive/src/test/java/org/springframework/web/reactive/view/freemarker/FreeMarkerViewTests.java

@@ -0,0 +1,150 @@
+/*
+ * Copyright 2002-2016 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.reactive.view.freemarker;
+
+import java.net.URI;
+import java.nio.ByteBuffer;
+import java.nio.charset.Charset;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Optional;
+
+import freemarker.template.Configuration;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import reactor.core.publisher.Flux;
+import reactor.core.test.TestSubscriber;
+
+import org.springframework.context.ApplicationContextException;
+import org.springframework.context.support.GenericApplicationContext;
+import org.springframework.core.ResolvableType;
+import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.server.reactive.MockServerHttpRequest;
+import org.springframework.http.server.reactive.MockServerHttpResponse;
+import org.springframework.ui.ExtendedModelMap;
+import org.springframework.ui.ModelMap;
+import org.springframework.web.context.WebApplicationContext;
+import org.springframework.web.reactive.HandlerResult;
+import org.springframework.web.server.ServerWebExchange;
+import org.springframework.web.server.adapter.DefaultServerWebExchange;
+import org.springframework.web.server.session.DefaultWebSessionManager;
+import org.springframework.web.server.session.WebSessionManager;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * @author Rossen Stoyanchev
+ */
+public class FreeMarkerViewTests {
+
+	public static final String TEMPLATE_PATH = "classpath*:org/springframework/web/reactive/view/freemarker/";
+
+	private static final Charset UTF_8 = Charset.forName("UTF-8");
+
+
+	private ServerWebExchange exchange;
+
+	private GenericApplicationContext context;
+
+	private Configuration freeMarkerConfig;
+
+	@Rule
+	public final ExpectedException exception = ExpectedException.none();
+
+
+	@Before
+	public void setUp() throws Exception {
+		this.context = new GenericApplicationContext();
+		this.context.refresh();
+
+		FreeMarkerConfigurer configurer = new FreeMarkerConfigurer();
+		configurer.setPreferFileSystemAccess(false);
+		configurer.setTemplateLoaderPath(TEMPLATE_PATH);
+		configurer.setResourceLoader(this.context);
+		this.freeMarkerConfig = configurer.createConfiguration();
+
+		FreeMarkerView fv = new FreeMarkerView();
+		fv.setApplicationContext(this.context);
+
+		MockServerHttpRequest request = new MockServerHttpRequest(HttpMethod.GET, new URI("/path"));
+		MockServerHttpResponse response = new MockServerHttpResponse();
+		WebSessionManager manager = new DefaultWebSessionManager();
+		this.exchange = new DefaultServerWebExchange(request, response, manager);
+	}
+
+
+	@Test
+	public void noFreeMarkerConfig() throws Exception {
+		this.exception.expect(ApplicationContextException.class);
+		this.exception.expectMessage("Must define a single FreeMarkerConfig bean");
+
+		FreeMarkerView view = new FreeMarkerView();
+		view.setApplicationContext(this.context);
+		view.setUrl("anythingButNull");
+		view.afterPropertiesSet();
+	}
+
+	@Test
+	public void noTemplateName() throws Exception {
+		this.exception.expect(IllegalArgumentException.class);
+		this.exception.expectMessage("Property 'url' is required");
+
+		FreeMarkerView freeMarkerView = new FreeMarkerView();
+		freeMarkerView.afterPropertiesSet();
+	}
+
+	@Test
+	public void checkResourceExists() throws Exception {
+		FreeMarkerView view = new FreeMarkerView();
+		view.setConfiguration(this.freeMarkerConfig);
+		view.setUrl("test.ftl");
+
+		assertTrue(view.checkResourceExists(Locale.US));
+	}
+
+	@Test
+	public void render() throws Exception {
+		FreeMarkerView view = new FreeMarkerView();
+		view.setConfiguration(this.freeMarkerConfig);
+		view.setUrl("test.ftl");
+
+		ModelMap model = new ExtendedModelMap();
+		model.addAttribute("hello", "hi FreeMarker");
+		HandlerResult result = new HandlerResult(new Object(), "", ResolvableType.NONE, model);
+		Flux<DataBuffer> flux = view.render(result, Optional.empty(), this.exchange);
+
+		TestSubscriber<DataBuffer> subscriber = new TestSubscriber<>();
+		subscriber.bindTo(flux).assertValuesWith(dataBuffer ->
+					assertEquals("<html><body>hi FreeMarker</body></html>", asString(dataBuffer)));
+	}
+
+
+
+	private static String asString(DataBuffer dataBuffer) {
+		ByteBuffer byteBuffer = dataBuffer.asByteBuffer();
+		final byte[] bytes = new byte[byteBuffer.remaining()];
+		byteBuffer.get(bytes);
+		return new String(bytes, UTF_8);
+	}
+
+}

spring-web-reactive/src/test/resources/org/springframework/web/reactive/view/freemarker/test.ftl

@@ -0,0 +1 @@
+<html><body>${hello}</body></html>