Add JSONP support for MappingJackson2MessageConverter

Issue: SPR-9899

Author: rstoyanchev

spring-web/src/main/java/org/springframework/http/converter/json/MappingJackson2HttpMessageConverter.java

@@ -249,15 +249,27 @@ protected void writeInternal(Object object, HttpOutputMessage outputMessage)
 			if (this.jsonPrefix != null) {
 				jsonGenerator.writeRaw(this.jsonPrefix);
 			}
+			Class<?> serializationView = null;
+			String jsonpFunction = null;
 			if (object instanceof MappingJacksonValue) {
-				MappingJacksonValue valueHolder = (MappingJacksonValue) object;
-				object = valueHolder.getValue();
-				Class<?> serializationView = valueHolder.getSerializationView();
+				MappingJacksonValue container = (MappingJacksonValue) object;
+				object = container.getValue();
+				serializationView = container.getSerializationView();
+				jsonpFunction = container.getJsonpFunction();
+			}
+			if (jsonpFunction != null) {
+				jsonGenerator.writeRaw(jsonpFunction + "(" );
+			}
+			if (serializationView != null) {
 				this.objectMapper.writerWithView(serializationView).writeValue(jsonGenerator, object);
 			}
 			else {
 				this.objectMapper.writeValue(jsonGenerator, object);
 			}
+			if (jsonpFunction != null) {
+				jsonGenerator.writeRaw(");");
+				jsonGenerator.flush();
+			}
 		}
 		catch (JsonProcessingException ex) {
 			throw new HttpMessageNotWritableException("Could not write JSON: " + ex.getMessage(), ex);

spring-web/src/main/java/org/springframework/http/converter/json/MappingJacksonValue.java

@@ -17,44 +17,83 @@
 package org.springframework.http.converter.json;
 
 /**
- * Holds an Object to be serialized via Jackson together with a serialization
- * view to be applied.
+ * A simple holder for the POJO to serialize via
+ * {@link org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+ * MappingJackson2HttpMessageConverter} along with further serialization
+ * instructions to be passed in to the converter.
+ *
+ * <p>On the server side this wrapper is added with a
+ * {@code ResponseBodyInterceptor} after content negotiation selects the
+ * converter to use but before the write.
+ *
+ * <p>On the client side, simply wrap the POJO and pass it in to the
+ * {@code RestTemplate}.
  *
  * @author Rossen Stoyanchev
  * @since 4.1
- *
- * @see com.fasterxml.jackson.annotation.JsonView
  */
 public class MappingJacksonValue {
 
-	private final Object value;
+	private Object value;
 
-	private final Class<?> serializationView;
+	private Class<?> serializationView;
+
+	private String jsonpFunction;
 
 
 	/**
-	 * Create a new instance.
+	 * Create a new instance wrapping the given POJO to be serialized.
 	 * @param value the Object to be serialized
-	 * @param serializationView the view to be applied
 	 */
-	public MappingJacksonValue(Object value, Class<?> serializationView) {
+	public MappingJacksonValue(Object value) {
 		this.value = value;
-		this.serializationView = serializationView;
 	}
 
 
 	/**
-	 * Return the value to be serialized.
+	 * Modify the POJO to serialize.
+	 */
+	public void setValue(Object value) {
+		this.value = value;
+	}
+
+	/**
+	 * Return the POJO that needs to be serialized.
 	 */
 	public Object getValue() {
 		return this.value;
 	}
 
+	/**
+	 * Set the serialization view to serialize the POJO with.
+	 * @see com.fasterxml.jackson.databind.ObjectMapper#writerWithView(Class)
+	 * @see com.fasterxml.jackson.annotation.JsonView
+	 */
+	public void setSerializationView(Class<?> serializationView) {
+		this.serializationView = serializationView;
+	}
+
 	/**
 	 * Return the serialization view to use.
+	 * @see com.fasterxml.jackson.databind.ObjectMapper#writerWithView(Class)
+	 * @see com.fasterxml.jackson.annotation.JsonView
 	 */
 	public Class<?> getSerializationView() {
 		return this.serializationView;
 	}
 
+	/**
+	 * Set the name of the JSONP function name.
+	 */
+	public void setJsonpFunction(String functionName) {
+		this.jsonpFunction = functionName;
+	}
+
+	/**
+	 * Return the configured JSONP function name.
+	 */
+	public String getJsonpFunction() {
+		return this.jsonpFunction;
+	}
+
 }

spring-web/src/test/java/org/springframework/http/converter/json/MappingJackson2HttpMessageConverterTests.java

@@ -27,6 +27,7 @@
 import com.fasterxml.jackson.annotation.JsonView;
 import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import org.hamcrest.CoreMatchers;
 import org.junit.Test;
 
 import org.springframework.core.ParameterizedTypeReference;
@@ -35,6 +36,7 @@
 import org.springframework.http.MockHttpOutputMessage;
 import org.springframework.http.converter.HttpMessageNotReadableException;
 
+import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
 
 /**
@@ -245,13 +247,48 @@ public void jsonView() throws Exception {
 		bean.setWithView1("with");
 		bean.setWithView2("with");
 		bean.setWithoutView("without");
-		MappingJacksonValue jsv = new MappingJacksonValue(bean, MyJacksonView1.class);
-		this.converter.writeInternal(jsv, outputMessage);
+
+		MappingJacksonValue jacksonValue = new MappingJacksonValue(bean);
+		jacksonValue.setSerializationView(MyJacksonView1.class);
+		this.converter.writeInternal(jacksonValue, outputMessage);
+
+		String result = outputMessage.getBodyAsString(Charset.forName("UTF-8"));
+		assertThat(result, containsString("\"withView1\":\"with\""));
+		assertThat(result, containsString("\"withoutView\":\"without\""));
+		assertThat(result, not(containsString("\"withView2\":\"with\"")));
+	}
+
+	@Test
+	public void jsonp() throws Exception {
+		MappingJacksonValue jacksonValue = new MappingJacksonValue("foo");
+		jacksonValue.setSerializationView(MyJacksonView1.class);
+		jacksonValue.setJsonpFunction("callback");
+
+		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
+		this.converter.writeInternal(jacksonValue, outputMessage);
+
+		assertEquals("callback(\"foo\");", outputMessage.getBodyAsString(Charset.forName("UTF-8")));
+	}
+
+	@Test
+	public void jsonpAndJsonView() throws Exception {
+		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
+		JacksonViewBean bean = new JacksonViewBean();
+		bean.setWithView1("with");
+		bean.setWithView2("with");
+		bean.setWithoutView("without");
+
+		MappingJacksonValue jacksonValue = new MappingJacksonValue(bean);
+		jacksonValue.setSerializationView(MyJacksonView1.class);
+		jacksonValue.setJsonpFunction("callback");
+		this.converter.writeInternal(jacksonValue, outputMessage);
 
 		String result = outputMessage.getBodyAsString(Charset.forName("UTF-8"));
-		assertTrue(result.contains("\"withView1\":\"with\""));
-		assertFalse(result.contains("\"withView2\":\"with\""));
-		assertTrue(result.contains("\"withoutView\":\"without\""));
+		assertThat(result, startsWith("callback("));
+		assertThat(result, endsWith(");"));
+		assertThat(result, containsString("\"withView1\":\"with\""));
+		assertThat(result, containsString("\"withoutView\":\"without\""));
+		assertThat(result, not(containsString("\"withView2\":\"with\"")));
 	}
 
 

spring-web/src/test/java/org/springframework/web/client/RestTemplateIntegrationTests.java

@@ -220,8 +220,9 @@ public void jsonPostForObjectWithJacksonView() throws URISyntaxException {
 		HttpHeaders entityHeaders = new HttpHeaders();
 		entityHeaders.setContentType(new MediaType("application", "json", Charset.forName("UTF-8")));
 		MySampleBean bean = new MySampleBean("with", "with", "without");
-		MappingJacksonValue jsv = new MappingJacksonValue(bean, MyJacksonView1.class);
-		HttpEntity<MappingJacksonValue> entity = new HttpEntity<MappingJacksonValue>(jsv);
+		MappingJacksonValue jacksonValue = new MappingJacksonValue(bean);
+		jacksonValue.setSerializationView(MyJacksonView1.class);
+		HttpEntity<MappingJacksonValue> entity = new HttpEntity<MappingJacksonValue>(jacksonValue);
 		String s = template.postForObject(baseUrl + "/jsonpost", entity, String.class, "post");
 		assertTrue(s.contains("\"with1\":\"with\""));
 		assertFalse(s.contains("\"with2\":\"with\""));

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AbstractJsonpResponseBodyInterceptor.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2002-2014 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.mvc.method.annotation;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.http.MediaType;
+import org.springframework.http.converter.json.MappingJacksonValue;
+import org.springframework.http.server.ServerHttpRequest;
+import org.springframework.http.server.ServerHttpResponse;
+import org.springframework.http.server.ServletServerHttpRequest;
+import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
+
+import javax.servlet.http.HttpServletRequest;
+import java.util.Collection;
+
+/**
+ * A convenient base class for a {@code ResponseBodyInterceptor} to instruct the
+ * {@link org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+ * MappingJackson2HttpMessageConverter} to serialize with JSONP formatting.
+ *
+ * <p>Sub-classes must specify the query parameter name(s) to check for the name
+ * of the JSONP callback function.
+ *
+ * <p>Sub-classes are likely to be annotated with the {@code @ControllerAdvice}
+ * annotation and auto-detected or otherwise must be registered directly with the
+ * {@code RequestMappingHandlerAdapter} and {@code ExceptionHandlerExceptionResolver}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.1
+ */
+public abstract class AbstractJsonpResponseBodyInterceptor extends AbstractMappingJacksonResponseBodyInterceptor {
+
+	private final String[] jsonpQueryParamNames;
+
+
+	protected AbstractJsonpResponseBodyInterceptor(Collection<String> queryParamNames) {
+		Assert.isTrue(!CollectionUtils.isEmpty(queryParamNames), "At least one query param name is required");
+		this.jsonpQueryParamNames = queryParamNames.toArray(new String[queryParamNames.size()]);
+	}
+
+
+	@Override
+	protected void beforeBodyWriteInternal(MappingJacksonValue bodyContainer, MediaType contentType,
+			MethodParameter returnType, ServerHttpRequest request, ServerHttpResponse response) {
+
+		HttpServletRequest servletRequest = ((ServletServerHttpRequest) request).getServletRequest();
+
+		for (String name : this.jsonpQueryParamNames) {
+			String value = servletRequest.getParameter(name);
+			if (value != null) {
+				MediaType contentTypeToUse = getContentType(contentType, request, response);
+				response.getHeaders().setContentType(contentTypeToUse);
+				bodyContainer.setJsonpFunction(value);
+				return;
+			}
+		}
+	}
+
+	/**
+	 * Return the content type to set the response to.
+	 * This implementation always returns "application/javascript".
+	 * @param contentType the content type selected through content negotiation
+	 * @param request the current request
+	 * @param response the current response
+	 * @return the content type to set the response to
+	 */
+	protected MediaType getContentType(MediaType contentType, ServerHttpRequest request, ServerHttpResponse response) {
+		return new MediaType("application", "javascript");
+	}
+
+}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AbstractMappingJacksonResponseBodyInterceptor.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2002-2014 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.mvc.method.annotation;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.http.MediaType;
+import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
+import org.springframework.http.converter.json.MappingJacksonValue;
+import org.springframework.http.server.ServerHttpRequest;
+import org.springframework.http.server.ServerHttpResponse;
+
+/**
+ * A convenient base class for {@code ResponseBodyInterceptor} implementations
+ * that customize the response before JSON serialization with
+ * {@link org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+ * MappingJackson2HttpMessageConverter}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.1
+ */
+public abstract class AbstractMappingJacksonResponseBodyInterceptor implements ResponseBodyInterceptor {
+
+
+	protected AbstractMappingJacksonResponseBodyInterceptor() {
+	}
+
+
+	@SuppressWarnings("unchecked")
+	@Override
+	public final <T> T beforeBodyWrite(T body, MediaType contentType,
+			Class<? extends HttpMessageConverter<T>> converterType,
+			MethodParameter returnType, ServerHttpRequest request, ServerHttpResponse response) {
+
+		if (!MappingJackson2HttpMessageConverter.class.equals(converterType)) {
+			return body;
+		}
+		MappingJacksonValue container = getOrCreateContainer(body);
+		beforeBodyWriteInternal(container, contentType, returnType, request, response);
+		return (T) container;
+	}
+
+	/**
+	 * Wrap the body in a {@link MappingJacksonValue} value container (for providing
+	 * additional serialization instructions) or simply cast it if already wrapped.
+	 */
+	protected MappingJacksonValue getOrCreateContainer(Object body) {
+		return (body instanceof MappingJacksonValue) ? (MappingJacksonValue) body : new MappingJacksonValue(body);
+	}
+
+	/**
+	 * Invoked only if the converter type is {@code MappingJackson2HttpMessageConverter}.
+	 */
+	protected abstract void beforeBodyWriteInternal(MappingJacksonValue bodyContainer, MediaType contentType,
+			MethodParameter returnType, ServerHttpRequest request, ServerHttpResponse response);
+
+
+}