Package 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:

MappingJackson2CborHttpMessageConverter, MappingJackson2HttpMessageConverter, MappingJackson2SmileHttpMessageConverter, MappingJackson2XmlHttpMessageConverter

public abstract class AbstractJackson2HttpMessageConverter
extends AbstractGenericHttpMessageConverter<Object>

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

Compatible with Jackson 2.9 to 2.12, as of Spring 5.3.

Since:

4.1

Author:

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

See Also:

• MappingJackson2HttpMessageConverter

Field Summary

Fields

Modifier and Type	Field	Description
protected ObjectMapper	defaultObjectMapper

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

logger

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	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 ObjectReader	customizeReader(ObjectReader reader, JavaType javaType)	Subclasses can use this method to customize ObjectReader used for reading values.
protected ObjectWriter	customizeWriter(ObjectWriter writer, JavaType javaType, MediaType contentType)	Subclasses can use this method to customize ObjectWriter used for writing values.
protected Charset	getCharset(MediaType contentType)	Determine the charset to use for JSON input.
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 main ObjectMapper in use.
Map<MediaType,ObjectMapper>	getObjectMappersForType(Class<?> clazz)	Return ObjectMapper registrations for the given class, if any.
List<MediaType>	getSupportedMediaTypes(Class<?> clazz)	Return the list of media types supported by this converter for the given class.
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	registerObjectMappersForType(Class<?> clazz, Consumer<Map<MediaType,ObjectMapper>> registrar)	Configure the ObjectMapper instances to use for the given Class.
void	setObjectMapper(ObjectMapper objectMapper)	Configure the main ObjectMapper to use for Object conversion.
void	setPrettyPrint(boolean prettyPrint)	Whether to use the DefaultPrettyPrinter when writing JSON.
void	setSupportedMediaTypes(List<MediaType> supportedMediaTypes)	Set the list of MediaType objects 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, supports, write, writeInternal

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

addDefaultHeaders, canRead, canWrite, getDefaultCharset, getSupportedMediaTypes, read, setDefaultCharset, 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 Details

defaultObjectMapper

protected ObjectMapper defaultObjectMapper

Constructor Details

AbstractJackson2HttpMessageConverter

protected AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper)

AbstractJackson2HttpMessageConverter

protected AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper,
 MediaType supportedMediaType)

AbstractJackson2HttpMessageConverter

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

Method Details

setSupportedMediaTypes

public void setSupportedMediaTypes(List<MediaType> supportedMediaTypes)

Description copied from class: AbstractHttpMessageConverter

Set the list of MediaType objects supported by this converter.

Overrides:

setSupportedMediaTypes in class AbstractHttpMessageConverter<Object>

setObjectMapper

public void setObjectMapper(ObjectMapper objectMapper)

Configure the main ObjectMapper to use for Object conversion. If not set, a default ObjectMapper instance is created.

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. Another 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.

See Also:

• registerObjectMappersForType(Class, Consumer)

getObjectMapper

public ObjectMapper getObjectMapper()

Return the main ObjectMapper in use.

registerObjectMappersForType

public void registerObjectMappersForType(Class<?> clazz,
 Consumer<Map<MediaType,ObjectMapper>> registrar)

Configure the ObjectMapper instances to use for the given Class. This is useful when you want to deviate from the default ObjectMapper or have the ObjectMapper vary by MediaType.

Note: Use of this method effectively turns off use of the default ObjectMapper and supportedMediaTypes for the given class. Therefore it is important for the mappings configured here to include every MediaType that must be supported for the given class.

Parameters:

clazz - the type of Object to register ObjectMapper instances for

registrar - a consumer to populate or otherwise update the MediaType-to-ObjectMapper associations for the given Class

Since:

5.3.4

getObjectMappersForType

@Nullable
public Map<MediaType,ObjectMapper> getObjectMappersForType(Class<?> clazz)

Return ObjectMapper registrations for the given class, if any.

Parameters:

clazz - the class to look up for registrations for

Returns:

a map with registered MediaType-to-ObjectMapper registrations, or empty if in case of no registrations for the given class.

Since:

5.3.4

getSupportedMediaTypes

public List<MediaType> getSupportedMediaTypes(Class<?> clazz)

Description copied from interface: HttpMessageConverter

Return the list of media types supported by this converter for the given class. The list may differ from HttpMessageConverter.getSupportedMediaTypes() if the converter does not support the given Class or if it supports it only for a subset of media types.

Parameters:

clazz - the type of class to check

Returns:

the list of media types supported for the given class

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,
 @Nullable
 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,
 @Nullable
 Class<?> contextClass,
 @Nullable
 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 as 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,
 @Nullable
 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,
 @Nullable
 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

read

public Object read(Type type,
 @Nullable
 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

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

customizeReader

protected ObjectReader customizeReader(ObjectReader reader,
 JavaType javaType)

Subclasses can use this method to customize ObjectReader used for reading values.

Parameters:

reader - the reader instance to customize

javaType - the target type of element values to read to

Returns:

the customized ObjectReader

Since:

6.0

getCharset

protected Charset getCharset(@Nullable
 MediaType contentType)

Determine the charset to use for JSON input.

By default this is either the charset from the input MediaType or otherwise falling back on UTF-8. Can be overridden in subclasses.

Parameters:

contentType - the content type of the HTTP input message

Returns:

the charset to use

Since:

5.1.18

writeInternal

protected void writeInternal(Object object,
 @Nullable
 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 (may be null)

outputMessage - the HTTP output message to write to

Throws:

IOException - in case of I/O errors

HttpMessageNotWritableException - in case of conversion errors

customizeWriter

protected ObjectWriter customizeWriter(ObjectWriter writer,
 @Nullable
 JavaType javaType,
 @Nullable
 MediaType contentType)

Subclasses can use this method to customize ObjectWriter used for writing values.

Parameters:

writer - the writer instance to customize

javaType - the type of element values to write

contentType - the selected media type

Returns:

the customized ObjectWriter

Since:

6.0

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,
 @Nullable
 Class<?> contextClass)

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

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(@Nullable
 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

@Nullable
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,
 @Nullable
 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