Class MessageHeaderAccessor
- Direct Known Subclasses:
NativeMessageHeaderAccessor
MessageHeaders
that provides extra features such as
strongly typed accessors for specific headers, the ability to leave headers
in a Message
mutable, and the option to suppress automatic generation
of id
and timesteamp
headers. Sub-classes such as NativeMessageHeaderAccessor
and others provide support for managing processing vs external source headers
as well as protocol specific headers.
Below is a workflow to initialize headers via MessageHeaderAccessor
,
or one of its sub-classes, then create a Message
, and then re-obtain
the accessor possibly from a different component:
// Create a message with headers MessageHeaderAccessor accessor = new MessageHeaderAccessor(); accessor.setHeader("foo", "bar"); MessageHeaders headers = accessor.getMessageHeaders(); Message message = MessageBuilder.createMessage("payload", headers); // Later on MessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message); Assert.notNull(accessor, "No MessageHeaderAccessor");
In order for the above to work, all participating components must use
MessageHeaders
to create, access, or modify headers, or otherwise
getAccessor(Message, Class)
will return null.
Below is a workflow that shows how headers are created and left mutable,
then modified possibly by a different component, and finally made immutable
perhaps before the possibility of being accessed on a different thread:
// Create a message with mutable headers MessageHeaderAccessor accessor = new MessageHeaderAccessor(); accessor.setHeader("foo", "bar"); accessor.setLeaveMutable(true); MessageHeaders headers = accessor.getMessageHeaders(); Message message = MessageBuilder.createMessage("payload", headers); // Later on MessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message); if (accessor.isMutable()) { // It's mutable, just change the headers accessor.setHeader("bar", "baz"); } else { // It's not, so get a mutable copy, change and re-create accessor = MessageHeaderAccessor.getMutableAccessor(message); accessor.setHeader("bar", "baz"); accessor.setLeaveMutable(true); // leave mutable again or not? message = MessageBuilder.createMessage(message.getPayload(), accessor); } // Make the accessor immutable MessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message); accessor.setImmutable();
- Since:
- 4.0
- Author:
- Rossen Stoyanchev, Juergen Hoeller
-
Field Summary
-
Constructor Summary
ConstructorDescriptionA constructor to create new headers.MessageHeaderAccessor
(Message<?> message) A constructor accepting the headers of an existing message to copy. -
Method Summary
Modifier and TypeMethodDescriptionvoid
copyHeaders
(Map<String, ?> headersToCopy) Copy the name-value pairs from the provided Map.void
copyHeadersIfAbsent
(Map<String, ?> headersToCopy) Copy the name-value pairs from the provided Map.protected MessageHeaderAccessor
createAccessor
(Message<?> message) Build a 'nested' accessor for the given message.static MessageHeaderAccessor
getAccessor
(Message<?> message) Return the originalMessageHeaderAccessor
used to create the headers of the givenMessage
, ornull
if that's not available or if its type does not match the required type.static <T extends MessageHeaderAccessor>
TgetAccessor
(Message<?> message, Class<T> requiredType) Return the originalMessageHeaderAccessor
used to create the headers of the givenMessage
, ornull
if that's not available or if its type does not match the required type.static <T extends MessageHeaderAccessor>
TgetAccessor
(MessageHeaders messageHeaders, Class<T> requiredType) A variation ofgetAccessor(org.springframework.messaging.Message, Class)
with aMessageHeaders
instance instead of aMessage
.getDetailedLogMessage
(Object payload) Return a more detailed message for logging purposes.protected String
getDetailedPayloadLogMessage
(Object payload) Retrieve the value for the header with the given name.getId()
Return the underlyingMessageHeaders
instance.static MessageHeaderAccessor
getMutableAccessor
(Message<?> message) Return a mutableMessageHeaderAccessor
for the given message attempting to match the type of accessor used to create the message headers, or otherwise wrapping the message with aMessageHeaderAccessor
instance.getShortLogMessage
(Object payload) Return a concise message for logging purposes.protected String
getShortPayloadLogMessage
(Object payload) boolean
Check whether the underlying message headers have been marked as modified.boolean
Whether the underlying headers can still be modified.protected boolean
protected boolean
isReadOnly
(String headerName) void
removeHeader
(String headerName) Remove the value for the given header name.void
removeHeaders
(String... headerPatterns) Removes all headers provided via array of 'headerPatterns'.void
setContentType
(MimeType contentType) void
setErrorChannel
(MessageChannel errorChannel) void
setErrorChannelName
(String errorChannelName) void
Set the value for the given header name.void
setHeaderIfAbsent
(String name, Object value) Set the value for the given header name only if the header name is not already associated with a value.void
By default whengetMessageHeaders()
is called,"this"
MessageHeaderAccessor
instance can no longer be used to modify the underlying message headers.void
setLeaveMutable
(boolean leaveMutable) By default whengetMessageHeaders()
is called,"this"
MessageHeaderAccessor
instance can no longer be used to modify the underlying message headers and the returnedMessageHeaders
is immutable.protected void
setModified
(boolean modified) Mark the underlying message headers as modified.void
setReplyChannel
(MessageChannel replyChannel) void
setReplyChannelName
(String replyChannelName) toMap()
Return a copy of the underlying header values as a plainMap
object.Return a copy of the underlying header values as aMessageHeaders
object.toString()
protected void
verifyType
(String headerName, Object headerValue)
-
Field Details
-
DEFAULT_CHARSET
The default charset used for headers.
-
-
Constructor Details
-
MessageHeaderAccessor
public MessageHeaderAccessor()A constructor to create new headers. -
MessageHeaderAccessor
A constructor accepting the headers of an existing message to copy.- Parameters:
message
- a message to copy the headers from, ornull
if none
-
-
Method Details
-
createAccessor
Build a 'nested' accessor for the given message.- Parameters:
message
- the message to build a new accessor for- Returns:
- the nested accessor (typically a specific subclass)
-
setLeaveMutable
public void setLeaveMutable(boolean leaveMutable) By default whengetMessageHeaders()
is called,"this"
MessageHeaderAccessor
instance can no longer be used to modify the underlying message headers and the returnedMessageHeaders
is immutable.However when this is set to
true
, the returned (underlying)MessageHeaders
instance remains mutable. To make further modifications continue to use the same accessor instance or re-obtain it via:
MessageHeaderAccessor.getAccessor(Message, Class)
When modifications are complete use
setImmutable()
to prevent further changes. The intended use case for this mechanism is initialization of a Message within a single thread.By default this is set to
false
.- Since:
- 4.1
-
setImmutable
public void setImmutable()By default whengetMessageHeaders()
is called,"this"
MessageHeaderAccessor
instance can no longer be used to modify the underlying message headers. However ifsetLeaveMutable(boolean)
is used, this method is necessary to indicate explicitly when theMessageHeaders
instance should no longer be modified.- Since:
- 4.1
-
isMutable
public boolean isMutable()Whether the underlying headers can still be modified.- Since:
- 4.1
-
setModified
protected void setModified(boolean modified) Mark the underlying message headers as modified.- Parameters:
modified
- typicallytrue
, orfalse
to reset the flag- Since:
- 4.1
-
isModified
public boolean isModified()Check whether the underlying message headers have been marked as modified.- Returns:
true
if the flag has been set,false
otherwise
-
getMessageHeaders
Return the underlyingMessageHeaders
instance.Unless
setLeaveMutable(boolean)
was set totrue
, after this call, the headers are immutable and this accessor can no longer modify them.This method always returns the same
MessageHeaders
instance if invoked multiples times. To obtain a copy of the underlying headers, usetoMessageHeaders()
ortoMap()
instead.- Since:
- 4.1
-
toMessageHeaders
Return a copy of the underlying header values as aMessageHeaders
object.This method can be invoked many times, with modifications in between where each new call returns a fresh copy of the current header values.
- Since:
- 4.1
-
toMap
Return a copy of the underlying header values as a plainMap
object.This method can be invoked many times, with modifications in between where each new call returns a fresh copy of the current header values.
-
getHeader
Retrieve the value for the header with the given name.- Parameters:
headerName
- the name of the header- Returns:
- the associated value, or
null
if none found
-
setHeader
Set the value for the given header name.If the provided value is
null
, the header will be removed. -
verifyType
-
setHeaderIfAbsent
Set the value for the given header name only if the header name is not already associated with a value. -
removeHeader
Remove the value for the given header name. -
removeHeaders
Removes all headers provided via array of 'headerPatterns'.As the name suggests, array may contain simple matching patterns for header names. Supported pattern styles are: "xxx*", "*xxx", "*xxx*" and "xxx*yyy".
-
copyHeaders
Copy the name-value pairs from the provided Map.This operation will overwrite any existing values. Use
copyHeadersIfAbsent(Map)
to avoid overwriting values. -
copyHeadersIfAbsent
Copy the name-value pairs from the provided Map.This operation will not overwrite any existing values.
-
isReadOnly
-
getId
-
getTimestamp
-
setContentType
-
getContentType
-
setReplyChannelName
-
setReplyChannel
-
getReplyChannel
-
setErrorChannelName
-
setErrorChannel
-
getErrorChannel
-
getShortLogMessage
Return a concise message for logging purposes.- Parameters:
payload
- the payload that corresponds to the headers.- Returns:
- the message
-
getDetailedLogMessage
Return a more detailed message for logging purposes.- Parameters:
payload
- the payload that corresponds to the headers.- Returns:
- the message
-
getShortPayloadLogMessage
-
getDetailedPayloadLogMessage
-
isReadableContentType
protected boolean isReadableContentType() -
toString
-
getAccessor
Return the originalMessageHeaderAccessor
used to create the headers of the givenMessage
, ornull
if that's not available or if its type does not match the required type.This is for cases where the existence of an accessor is strongly expected (followed up with an assertion) or where an accessor will be created otherwise.
- Parameters:
message
- the message to get an accessor for- Returns:
- an accessor instance of the specified type, or
null
if none - Since:
- 5.1.19
-
getAccessor
@Nullable public static <T extends MessageHeaderAccessor> T getAccessor(Message<?> message, @Nullable Class<T> requiredType) Return the originalMessageHeaderAccessor
used to create the headers of the givenMessage
, ornull
if that's not available or if its type does not match the required type.This is for cases where the existence of an accessor is strongly expected (followed up with an assertion) or where an accessor will be created otherwise.
- Parameters:
message
- the message to get an accessor forrequiredType
- the required accessor type (ornull
for any)- Returns:
- an accessor instance of the specified type, or
null
if none - Since:
- 4.1
-
getAccessor
@Nullable public static <T extends MessageHeaderAccessor> T getAccessor(MessageHeaders messageHeaders, @Nullable Class<T> requiredType) A variation ofgetAccessor(org.springframework.messaging.Message, Class)
with aMessageHeaders
instance instead of aMessage
.This is for cases when a full message may not have been created yet.
- Parameters:
messageHeaders
- the message headers to get an accessor forrequiredType
- the required accessor type (ornull
for any)- Returns:
- an accessor instance of the specified type, or
null
if none - Since:
- 4.1
-
getMutableAccessor
Return a mutableMessageHeaderAccessor
for the given message attempting to match the type of accessor used to create the message headers, or otherwise wrapping the message with aMessageHeaderAccessor
instance.This is for cases where a header needs to be updated in generic code while preserving the accessor type for downstream processing.
- Returns:
- an accessor of the required type (never
null
) - Since:
- 4.1
-