org.axonframework.messaging

Class MetaData

java.lang.Object

org.axonframework.messaging.MetaData

All Implemented Interfaces:

Serializable, Map<String,Object>

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

Represents MetaData that is passed along with a payload in a Message. Typically, the MetaData contains information about the message payload that isn't "domain-specific". Examples are originating IP-address or executing User ID.

Since:

2.0

Author:

Allard Buijze

See Also:

Serialized Form

Nested Class Summary

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

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
MetaData(Map<String,?> items) Initializes a MetaData instance with the given items as content.

Method Summary

Modifier and Type	Method and Description
MetaData	and(String key, Object value) Returns a MetaData instances containing the current entries, and the given key and given value.
MetaData	andIfNotPresent(String key, Supplier<Object> value) Returns a MetaData instances containing the current entries, and the given key if it was not yet present in this MetaData.
void	clear() This operation is not supported.
boolean	containsKey(Object key)
boolean	containsValue(Object value)
static MetaData	emptyInstance() Returns an empty MetaData instance.
Set<Map.Entry<String,Object>>	entrySet()
boolean	equals(Object o)
static MetaData	from(Map<String,?> metaDataEntries) Creates a new MetaData instance from the given metaDataEntries.
Object	get(Object key)
int	hashCode()
boolean	isEmpty()
Set<String>	keySet()
MetaData	mergedWith(Map<String,?> additionalEntries) Returns a MetaData instance containing values of this, combined with the given additionalEntries.
Object	put(String key, Object value) This operation is not supported.
void	putAll(Map<? extends String,?> m) This operation is not supported.
protected Object	readResolve() Java Serialization specification method that will ensure that deserialization will maintain a single instance of empty MetaData.
Object	remove(Object key) This operation is not supported.
int	size()
MetaData	subset(String... keys) Returns a MetaData instance containing a subset of the keys in this instance.
String	toString()
Collection<Object>	values()
static MetaData	with(String key, Object value) Creates a MetaData instances with a single entry, with the given key and given value.
MetaData	withoutKeys(Set<String> keys) Returns a MetaData instance with the items with given keys removed.

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

Constructor Detail

MetaData

public MetaData(@Nonnull
                Map<String,?> items)

Initializes a MetaData instance with the given items as content. Note that the items are copied into the MetaData. Modifications in the Map of items will not reflect is the MetaData, or vice versa. Modifications in the items themselves are reflected in the MetaData.

Parameters:

items - the items to populate the MetaData with

Method Detail

emptyInstance

public static MetaData emptyInstance()

Returns an empty MetaData instance.

Returns:

an empty MetaData instance

from

public static MetaData from(@Nullable
                            Map<String,?> metaDataEntries)

Creates a new MetaData instance from the given metaDataEntries. If metaDataEntries is already a MetaData instance, it is returned as is. This makes this method more suitable than the MetaData(java.util.Map) copy-constructor.

Parameters:

metaDataEntries - the items to populate the MetaData with

Returns:

a MetaData instance with the given metaDataEntries as content

with

public static MetaData with(@Nonnull
                            String key,
                            @Nullable
                            Object value)

Creates a MetaData instances with a single entry, with the given key and given value.

Parameters:

key - The key for the entry

value - The value of the entry

Returns:

a MetaData instance with a single entry

and

public MetaData and(@Nonnull
                    String key,
                    @Nullable
                    Object value)

Returns a MetaData instances containing the current entries, and the given key and given value. If key already existed, it's old value is overwritten with the given value.

Parameters:

key - The key for the entry

value - The value of the entry

Returns:

a MetaData instance with an additional entry

andIfNotPresent

public MetaData andIfNotPresent(@Nonnull
                                String key,
                                @Nonnull
                                Supplier<Object> value)

Returns a MetaData instances containing the current entries, and the given key if it was not yet present in this MetaData. If key already existed, the current value will be used. Otherwise the Supplier function will provide the value for key

Parameters:

key - The key for the entry

value - A Supplier function which provides the value

Returns:

a MetaData instance with an additional entry

get

public Object get(Object key)

Specified by:

get in interface Map<String,Object>

put

public Object put(String key,
                  Object value)

This operation is not supported.

Specified by:

put in interface Map<String,Object>

remove

public Object remove(Object key)

This operation is not supported.

Specified by:

remove in interface Map<String,Object>

putAll

public void putAll(@Nonnull
                   Map<? extends String,?> m)

This operation is not supported.

Specified by:

putAll in interface Map<String,Object>

clear

public void clear()

This operation is not supported.

Specified by:

clear in interface Map<String,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>

keySet

public Set<String> keySet()

Specified by:

keySet in interface Map<String,Object>

values

public Collection<Object> values()

Specified by:

values in interface Map<String,Object>

entrySet

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

Specified by:

entrySet in interface Map<String,Object>

size

public int size()

Specified by:

size in interface Map<String,Object>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<String,Object>

equals

public boolean equals(Object o)

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

mergedWith

public MetaData mergedWith(@Nonnull
                           Map<String,?> additionalEntries)

Returns a MetaData instance containing values of this, combined with the given additionalEntries. If any entries have identical keys, the values from the additionalEntries will take precedence.

Parameters:

additionalEntries - The additional entries for the new MetaData

Returns:

a MetaData instance containing values of this, combined with the given additionalEntries

withoutKeys

public MetaData withoutKeys(@Nonnull
                            Set<String> keys)

Returns a MetaData instance with the items with given keys removed. Keys for which there is no assigned value are ignored.
This MetaData instance is not influenced by this operation.

Parameters:

keys - The keys of the entries to remove

Returns:

a MetaData instance without the given keys

subset

public MetaData subset(String... keys)

Returns a MetaData instance containing a subset of the keys in this instance. Keys for which there is no assigned value are ignored.<

Parameters:

keys - The keys of the entries to remove

Returns:

a MetaData instance containing the given keys if these were already present

readResolve

protected Object readResolve()

Java Serialization specification method that will ensure that deserialization will maintain a single instance of empty MetaData.

Returns:

the MetaData instance to use after deserialization

toString

public String toString()

Overrides:

toString in class Object