org.springframework.messaging

Class MessageHeaders

java.lang.Object

org.springframework.messaging.MessageHeaders

All Implemented Interfaces:

Serializable, Map<String,Object>

public class MessageHeaders
extends Object
implements Map<String,Object>, Serializable

The headers for a Message.

IMPORTANT: This class is immutable. Any mutating operation such as put(..), putAll(..) and others will throw UnsupportedOperationException.

Subclasses do have access to the raw headers, however, via getRawHeaders().

One way to create message headers is to use the MessageBuilder:

 MessageBuilder.withPayload("foo").setHeader("key1", "value1").setHeader("key2", "value2");
 

A second option is to create GenericMessage passing a payload as Object and headers as a java.util.Map:

 Map headers = new HashMap();
 headers.put("key1", "value1");
 headers.put("key2", "value2");
 new GenericMessage("foo", headers);
 

A third option is to use MessageHeaderAccessor or one of its subclasses to create specific categories of headers.

Since:

4.0

Author:

Arjen Poutsma, Mark Fisher, Gary Russell

See Also:

MessageBuilder, MessageHeaderAccessor, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Field Summary

Fields

Modifier and Type	Field and Description
static String	CONTENT_TYPE
static String	ERROR_CHANNEL
static String	ID The key for the Message ID.
static UUID	ID_VALUE_NONE
static String	REPLY_CHANNEL
static String	TIMESTAMP

Constructor Summary

Constructors

Modifier	Constructor and Description
	MessageHeaders(Map<String,Object> headers) Construct a MessageHeaders with the given headers.
protected	MessageHeaders(Map<String,Object> headers, UUID id, Long timestamp) Constructor providing control over the ID and TIMESTAMP header values.

Method Summary

Modifier and Type	Method and Description
void	clear() Since MessageHeaders are immutable, the call to this method will result in UnsupportedOperationException.
boolean	containsKey(Object key)
boolean	containsValue(Object value)
Set<Map.Entry<String,Object>>	entrySet()
boolean	equals(Object other)
Object	get(Object key)
<T> T	get(Object key, Class<T> type)
Object	getErrorChannel()
UUID	getId()
protected static IdGenerator	getIdGenerator()
protected Map<String,Object>	getRawHeaders()
Object	getReplyChannel()
Long	getTimestamp()
int	hashCode()
boolean	isEmpty()
Set<String>	keySet()
Object	put(String key, Object value) Since MessageHeaders are immutable, the call to this method will result in UnsupportedOperationException.
void	putAll(Map<? extends String,? extends Object> map) Since MessageHeaders are immutable, the call to this method will result in UnsupportedOperationException.
Object	remove(Object key) Since MessageHeaders are immutable, the call to this method will result in UnsupportedOperationException.
int	size()
String	toString()
Collection<Object>	values()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

Field Detail

ID_VALUE_NONE

public static final UUID ID_VALUE_NONE

ID

public static final String ID

The key for the Message ID. This is an automatically generated UUID and should never be explicitly set in the header map except in the case of Message deserialization where the serialized Message's generated UUID is being restored.

See Also:

Constant Field Values

TIMESTAMP

public static final String TIMESTAMP

See Also:

Constant Field Values

REPLY_CHANNEL

public static final String REPLY_CHANNEL

See Also:

Constant Field Values

ERROR_CHANNEL

public static final String ERROR_CHANNEL

See Also:

Constant Field Values

CONTENT_TYPE

public static final String CONTENT_TYPE

See Also:

Constant Field Values

Constructor Detail

MessageHeaders

public MessageHeaders(Map<String,Object> headers)

Construct a MessageHeaders with the given headers. An ID and TIMESTAMP headers will also be added, overriding any existing values.

Parameters:

headers - a map with headers to add

MessageHeaders

protected MessageHeaders(Map<String,Object> headers,
                         UUID id,
                         Long timestamp)

Constructor providing control over the ID and TIMESTAMP header values.

Parameters:

headers - a map with headers to add

id - the ID header value

timestamp - the TIMESTAMP header value

Method Detail

getRawHeaders

protected Map<String,Object> getRawHeaders()

getIdGenerator

protected static IdGenerator getIdGenerator()

getId

public UUID getId()

getTimestamp

public Long getTimestamp()

getReplyChannel

public Object getReplyChannel()

getErrorChannel

public Object getErrorChannel()

get

public <T> T get(Object key,
                 Class<T> type)

equals

public boolean equals(Object other)

Specified by:

equals in interface Map<String,Object>

Overrides:

equals in class Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Map<String,Object>

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<String,Object>

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<String,Object>

entrySet

public Set<Map.Entry<String,Object>> entrySet()

Specified by:

entrySet in interface Map<String,Object>

get

public Object get(Object key)

Specified by:

get in interface Map<String,Object>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<String,Object>

keySet

public Set<String> keySet()

Specified by:

keySet in interface Map<String,Object>

size

public int size()

Specified by:

size in interface Map<String,Object>

values

public Collection<Object> values()

Specified by:

values in interface Map<String,Object>

put

public Object put(String key,
                  Object value)

Since MessageHeaders are immutable, the call to this method will result in UnsupportedOperationException.

Specified by:

put in interface Map<String,Object>

putAll

public void putAll(Map<? extends String,? extends Object> map)

Since MessageHeaders are immutable, the call to this method will result in UnsupportedOperationException.

Specified by:

putAll in interface Map<String,Object>

remove

public Object remove(Object key)

Since MessageHeaders are immutable, the call to this method will result in UnsupportedOperationException.

Specified by:

remove in interface Map<String,Object>

clear

public void clear()

Since MessageHeaders are immutable, the call to this method will result in UnsupportedOperationException.

Specified by:

clear in interface Map<String,Object>