/*
* 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.http.converter.json;
import java.io.IOException;
import java.lang.reflect.Type;
import java.nio.charset.Charset;
import java.util.concurrent.atomic.AtomicReference;
import com.fasterxml.jackson.core.JsonEncoding;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.GenericHttpMessageConverter;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* Abstract base class for Jackson based and content type independent
* {@link HttpMessageConverter} implementations.
*
* <p>Compatible with Jackson 2.1 and higher.
*
* @author Arjen Poutsma
* @author Keith Donald
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @author Sebastien Deleuze
* @since 4.1
*/
public abstract class AbstractJackson2HttpMessageConverter extends AbstractHttpMessageConverter<Object>
implements GenericHttpMessageConverter<Object> {
public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
// Check for Jackson 2.3's overloaded canDeserialize/canSerialize variants with cause reference
private static final boolean jackson23Available = ClassUtils.hasMethod(ObjectMapper.class,
"canDeserialize", JavaType.class, AtomicReference.class);
protected ObjectMapper objectMapper;
private Boolean prettyPrint;
protected AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper) {
this.objectMapper = objectMapper;
}
protected AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper, MediaType supportedMediaType) {
super(supportedMediaType);
this.objectMapper = objectMapper;
}
protected AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper, MediaType... supportedMediaTypes) {
super(supportedMediaTypes);
this.objectMapper = objectMapper;
}
/**
* Set the {@code ObjectMapper} for this view.
* If not set, a default {@link ObjectMapper#ObjectMapper() ObjectMapper} is used.
* <p>Setting a custom-configured {@code ObjectMapper} is one way to take further
* control of the JSON serialization process. For example, an extended
* {@link com.fasterxml.jackson.databind.ser.SerializerFactory}
* can be configured that provides custom serializers for specific types.
* The other option for refining the serialization process is to use Jackson's
* provided annotations on the types to be serialized, in which case a
* custom-configured ObjectMapper is unnecessary.
*/
public void setObjectMapper(ObjectMapper objectMapper) {
Assert.notNull(objectMapper, "ObjectMapper must not be null");
this.objectMapper = objectMapper;
configurePrettyPrint();
}
/**
* Return the underlying {@code ObjectMapper} for this view.
*/
public ObjectMapper getObjectMapper() {
return this.objectMapper;
}
/**
* Whether to use the {@link DefaultPrettyPrinter} when writing JSON.
* This is a shortcut for setting up an {@code ObjectMapper} as follows:
* <pre class="code">
* ObjectMapper mapper = new ObjectMapper();
* mapper.configure(SerializationFeature.INDENT_OUTPUT, true);
* converter.setObjectMapper(mapper);
* </pre>
*/
public void setPrettyPrint(boolean prettyPrint) {
this.prettyPrint = prettyPrint;
configurePrettyPrint();
}
private void configurePrettyPrint() {
if (this.prettyPrint != null) {
this.objectMapper.configure(SerializationFeature.INDENT_OUTPUT, this.prettyPrint);
}
}
@Override
public boolean canRead(Class<?> clazz, MediaType mediaType) {
return canRead(clazz, null, mediaType);
}
@Override
public boolean canRead(Type type, Class<?> contextClass, MediaType mediaType) {
JavaType javaType = getJavaType(type, contextClass);
if (!jackson23Available || !logger.isWarnEnabled()) {
return (this.objectMapper.canDeserialize(javaType) && canRead(mediaType));
}
AtomicReference<Throwable> causeRef = new AtomicReference<Throwable>();
if (this.objectMapper.canDeserialize(javaType, causeRef) && canRead(mediaType)) {
return true;
}
Throwable cause = causeRef.get();
if (cause != null) {
String msg = "Failed to evaluate deserialization for type " + javaType;
if (logger.isDebugEnabled()) {
logger.warn(msg, cause);
}
else {
logger.warn(msg + ": " + cause);
}
}
return false;
}
@Override
public boolean canWrite(Class<?> clazz, MediaType mediaType) {
if (!jackson23Available || !logger.isWarnEnabled()) {
return (this.objectMapper.canSerialize(clazz) && canWrite(mediaType));
}
AtomicReference<Throwable> causeRef = new AtomicReference<Throwable>();
if (this.objectMapper.canSerialize(clazz, causeRef) && canWrite(mediaType)) {
return true;
}
Throwable cause = causeRef.get();
if (cause != null) {
String msg = "Failed to evaluate serialization for type [" + clazz + "]";
if (logger.isDebugEnabled()) {
logger.warn(msg, cause);
}
else {
logger.warn(msg + ": " + cause);
}
}
return false;
}
@Override
protected boolean supports(Class<?> clazz) {
// should not be called, since we override canRead/Write instead
throw new UnsupportedOperationException();
}
@Override
protected Object readInternal(Class<?> clazz, HttpInputMessage inputMessage)
throws IOException, HttpMessageNotReadableException {
JavaType javaType = getJavaType(clazz, null);
return readJavaType(javaType, inputMessage);
}
@Override
public Object read(Type type, Class<?> contextClass, HttpInputMessage inputMessage)
throws IOException, HttpMessageNotReadableException {
JavaType javaType = getJavaType(type, contextClass);
return readJavaType(javaType, inputMessage);
}
private Object readJavaType(JavaType javaType, HttpInputMessage inputMessage) {
try {
return this.objectMapper.readValue(inputMessage.getBody(), javaType);
}
catch (IOException ex) {
throw new HttpMessageNotReadableException("Could not read JSON: " + ex.getMessage(), ex);
}
}
@Override
protected void writeInternal(Object object, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
JsonEncoding encoding = getJsonEncoding(outputMessage.getHeaders().getContentType());
JsonGenerator generator = this.objectMapper.getFactory().createGenerator(outputMessage.getBody(), encoding);
try {
writePrefix(generator, object);
Class<?> serializationView = null;
Object value = object;
if (value instanceof MappingJacksonValue) {
MappingJacksonValue container = (MappingJacksonValue) object;
value = container.getValue();
serializationView = container.getSerializationView();
}
if (serializationView != null) {
this.objectMapper.writerWithView(serializationView).writeValue(generator, value);
}
else {
this.objectMapper.writeValue(generator, value);
}
writeSuffix(generator, object);
generator.flush();
}
catch (JsonProcessingException ex) {
throw new HttpMessageNotWritableException("Could not write content: " + ex.getMessage(), ex);
}
}
/**
* Write a prefix before the main content.
* @param generator the generator to use for writing content.
* @param object the object to write to the output message.
*/
protected void writePrefix(JsonGenerator generator, Object object) throws IOException {
}
/**
* Write a suffix after the main content.
* @param generator the generator to use for writing content.
* @param object the object to write to the output message.
*/
protected void writeSuffix(JsonGenerator generator, Object object) throws IOException {
}
/**
* Return the Jackson {@link JavaType} for the specified type and context class.
* <p>The default implementation returns {@code typeFactory.constructType(type, contextClass)},
* but this can be overridden in subclasses, to allow for custom generic collection handling.
* For instance:
* <pre class="code">
* protected JavaType getJavaType(Type type) {
* if (type instanceof Class && List.class.isAssignableFrom((Class)type)) {
* return TypeFactory.collectionType(ArrayList.class, MyBean.class);
* } else {
* return super.getJavaType(type);
* }
* }
* </pre>
* @param type the type to return the java type for
* @param contextClass a context class for the target type, for example a class
* in which the target type appears in a method signature, can be {@code null}
* signature, can be {@code null}
* @return the java type
*/
protected JavaType getJavaType(Type type, Class<?> contextClass) {
return this.objectMapper.getTypeFactory().constructType(type, contextClass);
}
/**
* Determine the JSON encoding to use for the given content type.
* @param contentType the media type as requested by the caller
* @return the JSON encoding to use (never {@code null})
*/
protected JsonEncoding getJsonEncoding(MediaType contentType) {
if (contentType != null && contentType.getCharSet() != null) {
Charset charset = contentType.getCharSet();
for (JsonEncoding encoding : JsonEncoding.values()) {
if (charset.name().equals(encoding.getJavaName())) {
return encoding;
}
}
}
return JsonEncoding.UTF8;
}
@Override
protected MediaType getDefaultContentType(Object object) throws IOException {
if (object instanceof MappingJacksonValue) {
object = ((MappingJacksonValue) object).getValue();
}
return super.getDefaultContentType(object);
}
@Override
protected Long getContentLength(Object object, MediaType contentType) throws IOException {
if (object instanceof MappingJacksonValue) {
object = ((MappingJacksonValue) object).getValue();
}
return super.getContentLength(object, contentType);
}
}