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, Juergen Hoeller
See Also:
MessageBuilder, MessageHeaderAccessor, Serialized Form

Nested Class Summary
- Nested classes/interfaces inherited from interface java.util.Map
  Map.Entry<K extends Object,V extends Object>

Field Summary

Fields
Modifier and Type	Field	Description
`static String`	`CONTENT_TYPE`	The key for the message content type.
`static String`	`ERROR_CHANNEL`	The key for the message error channel.
`static String`	`ID`	The key for the Message ID.
`static UUID`	`ID_VALUE_NONE`	UUID for none.
`static String`	`REPLY_CHANNEL`	The key for the message reply channel.
`static String`	`TIMESTAMP`	The key for the message timestamp.

Constructor Summary

Constructors
Modifier	Constructor	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

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	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
```
    UUID for 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
```
    The key for the message timestamp.
    See Also:
    Constant Field Values
  - CONTENT_TYPE
```
public static final String CONTENT_TYPE
```
    The key for the message content type.
    See Also:
    Constant Field Values
  - REPLY_CHANNEL
```
public static final String REPLY_CHANNEL
```
    The key for the message reply channel.
    See Also:
    Constant Field Values
  - ERROR_CHANNEL
```
public static final String ERROR_CHANNEL
```
    The key for the message error channel.
    See Also:
    Constant Field Values
- Constructor Detail
  - MessageHeaders
```
public MessageHeaders(@Nullable
                      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(@Nullable
                         Map<String,Object> headers,
                         @Nullable
                         UUID id,
                         @Nullable
                         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
```
@Nullable
public UUID getId()
```
  - getTimestamp
```
@Nullable
public Long getTimestamp()
```
  - getReplyChannel
```
@Nullable
public Object getReplyChannel()
```
  - getErrorChannel
```
@Nullable
public Object getErrorChannel()
```
  - get
```
@Nullable
public <T> T get(Object key,
                 Class<T> type)
```
  - 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
```
@Nullable
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>
  - equals
```
public boolean equals(@Nullable
                      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

Class MessageHeaders

Nested Class Summary

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

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Map

Field Detail

ID_VALUE_NONE

ID

TIMESTAMP

CONTENT_TYPE

REPLY_CHANNEL

ERROR_CHANNEL

Constructor Detail

MessageHeaders

MessageHeaders

Method Detail

getRawHeaders

getIdGenerator

getId

getTimestamp

getReplyChannel

getErrorChannel

get

containsKey

containsValue

entrySet

get

isEmpty

keySet

size

values

put

putAll

remove

clear

equals

hashCode

toString