org.springframework.http.converter.json

Class AbstractJackson2HttpMessageConverter

java.lang.Object

org.springframework.http.converter.AbstractHttpMessageConverter<T>

org.springframework.http.converter.AbstractGenericHttpMessageConverter<Object>

org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter

All Implemented Interfaces:

GenericHttpMessageConverter<Object>, HttpMessageConverter<Object>

Direct Known Subclasses:

MappingJackson2HttpMessageConverter, MappingJackson2XmlHttpMessageConverter

public abstract class AbstractJackson2HttpMessageConverter
extends AbstractGenericHttpMessageConverter<Object>

Abstract base class for Jackson based and content type independent HttpMessageConverter implementations.

Compatible with Jackson 2.6 and higher, as of Spring 4.3.

Since:

4.1

Author:

Arjen Poutsma, Keith Donald, Rossen Stoyanchev, Juergen Hoeller, Sebastien Deleuze

Field Summary

Fields

Modifier and Type	Field and Description
static Charset	DEFAULT_CHARSET
protected ObjectMapper	objectMapper

Fields inherited from class org.springframework.http.converter.AbstractHttpMessageConverter

logger

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper)
protected	AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper, MediaType... supportedMediaTypes)
protected	AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper, MediaType supportedMediaType)

Method Summary

Modifier and Type	Method and Description
boolean	canRead(Class<?> clazz, MediaType mediaType) This implementation checks if the given class is supported, and if the supported media types include the given media type.
boolean	canRead(Type type, Class<?> contextClass, MediaType mediaType) Indicates whether the given type can be read by this converter.
boolean	canWrite(Class<?> clazz, MediaType mediaType) This implementation checks if the given class is supported, and if the supported media types include the given media type.
protected Long	getContentLength(Object object, MediaType contentType) Returns the content length for the given type.
protected MediaType	getDefaultContentType(Object object) Returns the default content type for the given type.
protected JavaType	getJavaType(Type type, Class<?> contextClass) Return the Jackson JavaType for the specified type and context class.
protected JsonEncoding	getJsonEncoding(MediaType contentType) Determine the JSON encoding to use for the given content type.
ObjectMapper	getObjectMapper() Return the underlying ObjectMapper for this view.
protected void	logWarningIfNecessary(Type type, Throwable cause) Determine whether to log the given exception coming from a ObjectMapper.canDeserialize(com.fasterxml.jackson.databind.JavaType) / ObjectMapper.canSerialize(java.lang.Class<?>) check.
Object	read(Type type, Class<?> contextClass, HttpInputMessage inputMessage) Read an object of the given type form the given input message, and returns it.
protected Object	readInternal(Class<?> clazz, HttpInputMessage inputMessage) Abstract template method that reads the actual object.
void	setObjectMapper(ObjectMapper objectMapper) Set the ObjectMapper for this view.
void	setPrettyPrint(boolean prettyPrint) Whether to use the DefaultPrettyPrinter when writing JSON.
protected boolean	supports(Class<?> clazz) Indicates whether the given class is supported by this converter.
protected void	writeInternal(Object object, Type type, HttpOutputMessage outputMessage) Abstract template method that writes the actual body.
protected void	writePrefix(JsonGenerator generator, Object object) Write a prefix before the main content.
protected void	writeSuffix(JsonGenerator generator, Object object) Write a suffix after the main content.

Methods inherited from class org.springframework.http.converter.AbstractGenericHttpMessageConverter

canWrite, write, writeInternal

Methods inherited from class org.springframework.http.converter.AbstractHttpMessageConverter

addDefaultHeaders, canRead, canWrite, getDefaultCharset, getSupportedMediaTypes, read, setDefaultCharset, setSupportedMediaTypes, write

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.springframework.http.converter.HttpMessageConverter

getSupportedMediaTypes, read, write

Field Detail

DEFAULT_CHARSET

public static final Charset DEFAULT_CHARSET

objectMapper

protected ObjectMapper objectMapper

Constructor Detail

AbstractJackson2HttpMessageConverter

protected AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper)

AbstractJackson2HttpMessageConverter

protected AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper,
                                               MediaType supportedMediaType)

AbstractJackson2HttpMessageConverter

protected AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper,
                                               MediaType... supportedMediaTypes)

Method Detail

setObjectMapper

public void setObjectMapper(ObjectMapper objectMapper)

Set the ObjectMapper for this view. If not set, a default ObjectMapper is used.

Setting a custom-configured ObjectMapper is one way to take further control of the JSON serialization process. For example, an extended 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.

getObjectMapper

public ObjectMapper getObjectMapper()

Return the underlying ObjectMapper for this view.

setPrettyPrint

public void setPrettyPrint(boolean prettyPrint)

Whether to use the DefaultPrettyPrinter when writing JSON. This is a shortcut for setting up an ObjectMapper as follows:

 ObjectMapper mapper = new ObjectMapper();
 mapper.configure(SerializationFeature.INDENT_OUTPUT, true);
 converter.setObjectMapper(mapper);
 

canRead

public boolean canRead(Class<?> clazz,
                       MediaType mediaType)

Description copied from class: AbstractHttpMessageConverter

This implementation checks if the given class is supported, and if the supported media types include the given media type.

Specified by:

canRead in interface HttpMessageConverter<Object>

Overrides:

canRead in class AbstractHttpMessageConverter<Object>

Parameters:

clazz - the class to test for readability

mediaType - the media type to read, can be null if not specified. Typically the value of a Content-Type header.

Returns:

true if readable; false otherwise

canRead

public boolean canRead(Type type,
                       Class<?> contextClass,
                       MediaType mediaType)

Description copied from interface: GenericHttpMessageConverter

Indicates whether the given type can be read by this converter. This method should perform the same checks than HttpMessageConverter.canRead(Class, MediaType) with additional ones related to the generic type.

Specified by:

canRead in interface GenericHttpMessageConverter<Object>

Overrides:

canRead in class AbstractGenericHttpMessageConverter<Object>

Parameters:

type - the (potentially generic) type to test for readability

contextClass - a context class for the target type, for example a class in which the target type appears in a method signature (can be null)

mediaType - the media type to read, can be null if not specified. Typically the value of a Content-Type header.

Returns:

true if readable; false otherwise

canWrite

public boolean canWrite(Class<?> clazz,
                        MediaType mediaType)

Description copied from class: AbstractHttpMessageConverter

This implementation checks if the given class is supported, and if the supported media types include the given media type.

Specified by:

canWrite in interface HttpMessageConverter<Object>

Overrides:

canWrite in class AbstractHttpMessageConverter<Object>

Parameters:

clazz - the class to test for writability

mediaType - the media type to write, can be null if not specified. Typically the value of an Accept header.

Returns:

true if writable; false otherwise

logWarningIfNecessary

protected void logWarningIfNecessary(Type type,
                                     Throwable cause)

Determine whether to log the given exception coming from a ObjectMapper.canDeserialize(com.fasterxml.jackson.databind.JavaType) / ObjectMapper.canSerialize(java.lang.Class<?>) check.

Parameters:

type - the class that Jackson tested for (de-)serializability

cause - the Jackson-thrown exception to evaluate (typically a JsonMappingException)

Since:

4.3

supports

protected boolean supports(Class<?> clazz)

Description copied from class: AbstractHttpMessageConverter

Indicates whether the given class is supported by this converter.

Specified by:

supports in class AbstractHttpMessageConverter<Object>

Parameters:

clazz - the class to test for support

Returns:

true if supported; false otherwise

readInternal

protected Object readInternal(Class<?> clazz,
                              HttpInputMessage inputMessage)
                       throws IOException,
                              HttpMessageNotReadableException

Description copied from class: AbstractHttpMessageConverter

Abstract template method that reads the actual object. Invoked from AbstractHttpMessageConverter.read(java.lang.Class<? extends T>, org.springframework.http.HttpInputMessage).

Specified by:

readInternal in class AbstractHttpMessageConverter<Object>

Parameters:

clazz - the type of object to return

inputMessage - the HTTP input message to read from

Returns:

the converted object

Throws:

IOException - in case of I/O errors

HttpMessageNotReadableException - in case of conversion errors

read

public Object read(Type type,
                   Class<?> contextClass,
                   HttpInputMessage inputMessage)
            throws IOException,
                   HttpMessageNotReadableException

Description copied from interface: GenericHttpMessageConverter

Read an object of the given type form the given input message, and returns it.

Parameters:

type - the (potentially generic) type of object to return. This type must have previously been passed to the canRead method of this interface, which must have returned true.

contextClass - a context class for the target type, for example a class in which the target type appears in a method signature (can be null)

inputMessage - the HTTP input message to read from

Returns:

the converted object

Throws:

IOException - in case of I/O errors

HttpMessageNotReadableException - in case of conversion errors

writeInternal

protected void writeInternal(Object object,
                             Type type,
                             HttpOutputMessage outputMessage)
                      throws IOException,
                             HttpMessageNotWritableException

Description copied from class: AbstractGenericHttpMessageConverter

Abstract template method that writes the actual body. Invoked from AbstractGenericHttpMessageConverter.write(T, java.lang.reflect.Type, org.springframework.http.MediaType, org.springframework.http.HttpOutputMessage).

Specified by:

writeInternal in class AbstractGenericHttpMessageConverter<Object>

Parameters:

object - the object to write to the output message

type - the type of object to write, can be null if not specified.

outputMessage - the HTTP output message to write to

Throws:

IOException - in case of I/O errors

HttpMessageNotWritableException - in case of conversion errors

writePrefix

protected void writePrefix(JsonGenerator generator,
                           Object object)
                    throws IOException

Write a prefix before the main content.

Parameters:

generator - the generator to use for writing content.

object - the object to write to the output message.

Throws:

IOException

writeSuffix

protected void writeSuffix(JsonGenerator generator,
                           Object object)
                    throws IOException

Write a suffix after the main content.

Parameters:

generator - the generator to use for writing content.

object - the object to write to the output message.

Throws:

IOException

getJavaType

protected JavaType getJavaType(Type type,
                               Class<?> contextClass)

Return the Jackson JavaType for the specified type and context class.

The default implementation returns typeFactory.constructType(type, contextClass), but this can be overridden in subclasses, to allow for custom generic collection handling. For instance:

 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);
   }
 }
 

Parameters:

type - the generic type to return the Jackson JavaType for

contextClass - a context class for the target type, for example a class in which the target type appears in a method signature (can be null)

Returns:

the Jackson JavaType

getJsonEncoding

protected JsonEncoding getJsonEncoding(MediaType contentType)

Determine the JSON encoding to use for the given content type.

Parameters:

contentType - the media type as requested by the caller

Returns:

the JSON encoding to use (never null)

getDefaultContentType

protected MediaType getDefaultContentType(Object object)
                                   throws IOException

Description copied from class: AbstractHttpMessageConverter

Returns the default content type for the given type. Called when AbstractHttpMessageConverter.write(T, org.springframework.http.MediaType, org.springframework.http.HttpOutputMessage) is invoked without a specified content type parameter.

By default, this returns the first element of the supportedMediaTypes property, if any. Can be overridden in subclasses.

Overrides:

getDefaultContentType in class AbstractHttpMessageConverter<Object>

Parameters:

object - the type to return the content type for

Returns:

the content type, or null if not known

Throws:

IOException

getContentLength

protected Long getContentLength(Object object,
                                MediaType contentType)
                         throws IOException

Description copied from class: AbstractHttpMessageConverter

Returns the content length for the given type.

By default, this returns null, meaning that the content length is unknown. Can be overridden in subclasses.

Overrides:

getContentLength in class AbstractHttpMessageConverter<Object>

Parameters:

object - the type to return the content length for

Returns:

the content length, or null if not known

Throws:

IOException