public final class NamespaceManager
extends java.lang.Object
The "current namespace" is the string that is returned by
get()
and used by a number of APIs including Datatore,
Memcache and Task Queue.
When a namespace aware class (e.g.,
Key
,
Query
and
MemcacheService
) is constructed, it
determines which namespace will be used by calling
get()
if it is otherwise unspecified. If
get()
returns null, the current namespace is unset
and these APIs will use the empty ("") namespace in its place.
Example:
NamespaceManager
.set(java.lang.String)
("a-namespace");
MemcacheService memcache = MemcacheServiceFactory.getMemcacheService();
// Store record in namespace "a-namespace"
memcache.put("key1", "value1");
NamespaceManager
.set(java.lang.String)
("other-namespace");
// Store record in namespace "other-namespace"
memcache.put("key2", "value2");
MemcacheService boundMemcache =
MemcacheServiceFactory.getMemcacheService("specific-namespace");
NamespaceManager
.set(java.lang.String)
("whatever-namespace");
// The record is still stored in namespace "specific-namespace".
boundMemcache.put("key3", "value3");
MemcacheService
memcache
(in the above example) uses the current
namespace and
key1
will be stored in namespace
"a-namespace"
,
while
key2
is stored in namespace
"other-namespace"
. It is
possible to override the current namespace and store data in specific
namespace. In the above example
key3
is stored in namespace
"specific-namespace"
.
The Task Queue
Queue.add()
methods will forward the
NamespaceManager
settings into the task
being added causing the added task to be executed with the same current
namespace as the task creator. The exception is that an unset current
namespace (i.e.
get()
returns null) will be
forwarded as an empty ("") namespace to the created task's requests.
Modifier and Type | Method and Description |
---|---|
static java.lang.String
|
get
()
Returns the current namespace setting or
null
if not set.
|
static java.lang.String
|
getGoogleAppsNamespace
()
Returns the Google Apps domain referring this request or
otherwise the empty string ("").
|
static void
|
set
(java.lang.String newNamespace)
Set the value used to initialize the namespace of namespace-aware services.
|
static void
|
validateNamespace
(java.lang.String namespace)
Validate the format of a namespace string.
|
public static void set(java.lang.String newNamespace)
newNamespace
- the new namespace.
java.lang.IllegalArgumentException
- if namespace string is invalid.
public static java.lang.String get()
null
if not set.
If the current namespace is unset, callers should assume the use of the "" (empty) namespace in all namespace-aware services.
public static java.lang.String getGoogleAppsNamespace()
public static void validateNamespace(java.lang.String namespace)
java.lang.IllegalArgumentException
- If the format of the namespace string
is invalid.