org.springframework.messaging.converter

Class AbstractMessageConverter

java.lang.Object

org.springframework.messaging.converter.AbstractMessageConverter

All Implemented Interfaces:

MessageConverter, SmartMessageConverter

Direct Known Subclasses:

ByteArrayMessageConverter, MappingJackson2MessageConverter, MarshallingMessageConverter, StringMessageConverter

public abstract class AbstractMessageConverter
extends Object
implements SmartMessageConverter

Abstract base class for SmartMessageConverter implementations including support for common properties and a partial implementation of the conversion methods, mainly to check if the converter supports the conversion based on the payload class and MIME type.

Since:

4.0

Author:

Rossen Stoyanchev, Sebastien Deleuze, Juergen Hoeller

Field Summary

Fields

Modifier and Type	Field and Description
protected Log	logger

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractMessageConverter(Collection<MimeType> supportedMimeTypes) Construct an AbstractMessageConverter supporting multiple MIME types.
protected	AbstractMessageConverter(MimeType supportedMimeType) Construct an AbstractMessageConverter supporting a single MIME type.

Method Summary

Modifier and Type	Method and Description
protected boolean	canConvertFrom(Message<?> message, Class<?> targetClass)
protected boolean	canConvertTo(Object payload, MessageHeaders headers)
protected Object	convertFromInternal(Message<?> message, Class<?> targetClass, Object conversionHint) Convert the message payload from serialized form to an Object.
protected Object	convertToInternal(Object payload, MessageHeaders headers, Object conversionHint) Convert the payload object to serialized form.
Object	fromMessage(Message<?> message, Class<?> targetClass) Convert the payload of a Message from a serialized form to a typed Object of the specified target class.
Object	fromMessage(Message<?> message, Class<?> targetClass, Object conversionHint) A variant of MessageConverter.fromMessage(Message, Class) which takes an extra conversion context as an argument, allowing to take e.g.
ContentTypeResolver	getContentTypeResolver() Return the configured ContentTypeResolver.
protected MimeType	getDefaultContentType(Object payload) Return the default content type for the payload.
protected MimeType	getMimeType(MessageHeaders headers)
Class<?>	getSerializedPayloadClass() Return the configured preferred serialization payload class.
List<MimeType>	getSupportedMimeTypes() Return the supported MIME types.
boolean	isStrictContentTypeMatch() Whether content type resolution must produce a value that matches one of the supported MIME types.
void	setContentTypeResolver(ContentTypeResolver resolver) Configure the ContentTypeResolver to use to resolve the content type of an input message.
void	setSerializedPayloadClass(Class<?> payloadClass) Configure the preferred serialization class to use (byte[] or String) when converting an Object payload to a Message.
void	setStrictContentTypeMatch(boolean strictContentTypeMatch) Whether this converter should convert messages for which no content type could be resolved through the configured ContentTypeResolver.
protected abstract boolean	supports(Class<?> clazz) Whether the given class is supported by this converter.
protected boolean	supportsMimeType(MessageHeaders headers)
Message<?>	toMessage(Object payload, MessageHeaders headers) Create a Message whose payload is the result of converting the given payload Object to serialized form.
Message<?>	toMessage(Object payload, MessageHeaders headers, Object conversionHint) A variant of MessageConverter.toMessage(Object, MessageHeaders) which takes an extra conversion context as an argument, allowing to take e.g.

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected final Log logger

Constructor Detail

AbstractMessageConverter

protected AbstractMessageConverter(MimeType supportedMimeType)

Construct an AbstractMessageConverter supporting a single MIME type.

Parameters:

supportedMimeType - the supported MIME type

AbstractMessageConverter

protected AbstractMessageConverter(Collection<MimeType> supportedMimeTypes)

Construct an AbstractMessageConverter supporting multiple MIME types.

Parameters:

supportedMimeTypes - the supported MIME types

Method Detail

getSupportedMimeTypes

public List<MimeType> getSupportedMimeTypes()

Return the supported MIME types.

setContentTypeResolver

public void setContentTypeResolver(@Nullable
                                   ContentTypeResolver resolver)

Configure the ContentTypeResolver to use to resolve the content type of an input message.

Note that if no resolver is configured, then strictContentTypeMatch should be left as false (the default) or otherwise this converter will ignore all messages.

By default, a DefaultContentTypeResolver instance is used.

getContentTypeResolver

@Nullable
public ContentTypeResolver getContentTypeResolver()

Return the configured ContentTypeResolver.

setStrictContentTypeMatch

public void setStrictContentTypeMatch(boolean strictContentTypeMatch)

Whether this converter should convert messages for which no content type could be resolved through the configured ContentTypeResolver.

A converter can configured to be strict only when a contentTypeResolver is configured and the list of supportedMimeTypes is not be empty.

When this flag is set to true, supportsMimeType(MessageHeaders) will return false if the contentTypeResolver is not defined or if no content-type header is present.

isStrictContentTypeMatch

public boolean isStrictContentTypeMatch()

Whether content type resolution must produce a value that matches one of the supported MIME types.

setSerializedPayloadClass

public void setSerializedPayloadClass(Class<?> payloadClass)

Configure the preferred serialization class to use (byte[] or String) when converting an Object payload to a Message.

The default value is byte[].

Parameters:

payloadClass - either byte[] or String

getSerializedPayloadClass

public Class<?> getSerializedPayloadClass()

Return the configured preferred serialization payload class.

fromMessage

@Nullable
public final Object fromMessage(Message<?> message,
                                          Class<?> targetClass)

Description copied from interface: MessageConverter

Convert the payload of a Message from a serialized form to a typed Object of the specified target class. The MessageHeaders.CONTENT_TYPE header should indicate the MIME type to convert from.

If the converter does not support the specified media type or cannot perform the conversion, it should return null.

Specified by:

fromMessage in interface MessageConverter

Parameters:

message - the input message

targetClass - the target class for the conversion

Returns:

the result of the conversion, or null if the converter cannot perform the conversion

fromMessage

@Nullable
public final Object fromMessage(Message<?> message,
                                          Class<?> targetClass,
                                          @Nullable
                                          Object conversionHint)

Description copied from interface: SmartMessageConverter

A variant of MessageConverter.fromMessage(Message, Class) which takes an extra conversion context as an argument, allowing to take e.g. annotations on a payload parameter into account.

Specified by:

fromMessage in interface SmartMessageConverter

Parameters:

message - the input message

targetClass - the target class for the conversion

conversionHint - an extra object passed to the MessageConverter, e.g. the associated MethodParameter (may be null}

Returns:

the result of the conversion, or null if the converter cannot perform the conversion

See Also:

MessageConverter.fromMessage(Message, Class)

toMessage

@Nullable
public final Message<?> toMessage(Object payload,
                                            @Nullable
                                            MessageHeaders headers)

Description copied from interface: MessageConverter

Create a Message whose payload is the result of converting the given payload Object to serialized form. The optional MessageHeaders parameter may contain a MessageHeaders.CONTENT_TYPE header to specify the target media type for the conversion and it may contain additional headers to be added to the message.

If the converter does not support the specified media type or cannot perform the conversion, it should return null.

Specified by:

toMessage in interface MessageConverter

Parameters:

payload - the Object to convert

headers - optional headers for the message (may be null)

Returns:

the new message, or null if the converter does not support the Object type or the target media type

toMessage

@Nullable
public final Message<?> toMessage(Object payload,
                                            @Nullable
                                            MessageHeaders headers,
                                            @Nullable
                                            Object conversionHint)

Description copied from interface: SmartMessageConverter

A variant of MessageConverter.toMessage(Object, MessageHeaders) which takes an extra conversion context as an argument, allowing to take e.g. annotations on a return type into account.

Specified by:

toMessage in interface SmartMessageConverter

Parameters:

payload - the Object to convert

headers - optional headers for the message (may be null)

conversionHint - an extra object passed to the MessageConverter, e.g. the associated MethodParameter (may be null}

Returns:

the new message, or null if the converter does not support the Object type or the target media type

See Also:

MessageConverter.toMessage(Object, MessageHeaders)

canConvertFrom

protected boolean canConvertFrom(Message<?> message,
                                 Class<?> targetClass)

canConvertTo

protected boolean canConvertTo(Object payload,
                               @Nullable
                               MessageHeaders headers)

supportsMimeType

protected boolean supportsMimeType(@Nullable
                                   MessageHeaders headers)

getMimeType

@Nullable
protected MimeType getMimeType(@Nullable
                                         MessageHeaders headers)

getDefaultContentType

@Nullable
protected MimeType getDefaultContentType(Object payload)

Return the default content type for the payload. Called when toMessage(Object, MessageHeaders) is invoked without message headers or without a content type header.

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

Parameters:

payload - the payload being converted to a message

Returns:

the content type, or null if not known

supports

protected abstract boolean supports(Class<?> clazz)

Whether the given class is supported by this converter.

Parameters:

clazz - the class to test for support

Returns:

true if supported; false otherwise

convertFromInternal

@Nullable
protected Object convertFromInternal(Message<?> message,
                                               Class<?> targetClass,
                                               @Nullable
                                               Object conversionHint)

Convert the message payload from serialized form to an Object.

Parameters:

message - the input message

targetClass - the target class for the conversion

conversionHint - an extra object passed to the MessageConverter, e.g. the associated MethodParameter (may be null}

Returns:

the result of the conversion, or null if the converter cannot perform the conversion

Since:

4.2

convertToInternal

@Nullable
protected Object convertToInternal(Object payload,
                                             @Nullable
                                             MessageHeaders headers,
                                             @Nullable
                                             Object conversionHint)

Convert the payload object to serialized form.

Parameters:

payload - the Object to convert

headers - optional headers for the message (may be null)

conversionHint - an extra object passed to the MessageConverter, e.g. the associated MethodParameter (may be null}

Returns:

the resulting payload for the message, or null if the converter cannot perform the conversion

Since:

4.2