com.seanchenxi.gwt.storage.client

Class StorageExt

java.lang.Object

com.seanchenxi.gwt.storage.client.StorageExt

public final class StorageExt
extends Object

Extends the GWT HTML5 Storage API, by adding Object Value Support.

You can obtain a Storage by either invoking getLocalStorage() or getSessionStorage().

If Web Storage is NOT supported in the browser, these methods return null.

Note: Storage events into other windows are not supported.

This may not be supported on all browsers.

See Also:

W3C Web Storage - Storage, Can I use... - Web Storage, GWT Developer's Guide - Client-side Storage (Web Storage), com.google.gwt.storage.client.Storage

Method Summary

Modifier and Type	Method and Description
com.google.web.bindery.event.shared.HandlerRegistration	addStorageChangeHandler(StorageChangeEvent.Handler handler) Registers an event handler for StorageChangeEvent
void	clear() Removes all items in the Storage, and its cache if activated
void	clearCache() Clear all cached serialized object from configured StorageCache
<T> boolean	containsKey(StorageKey<T> key) Test if this storage contains a value for the specified key.
<T> T	get(StorageKey<T> key) Returns the value in the Storage associated with the specified key, or null if this Storage contains no mapping for the key.
static StorageExt	getLocalStorage() Returns a Local Storage.
static StorageExt	getSessionStorage() Returns a Session Storage.
String	getString(String key) Get directly the stored string value associated with the specified key.
String	key(int index) Returns the key at the specified index.
<T> void	put(StorageKey<T> key, T value) Store the specified value with the specified key in this storage.
<T extends Serializable> void	remove(StorageKey<T> key) Removes the record for the specified key from this storage if present.
void	setEventLevel(StorageChangeEvent.Level eventLevel) Set Event Level.
int	size() Returns the number of items in this Storage.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getLocalStorage

public static StorageExt getLocalStorage()

Returns a Local Storage.

Returns:

the localStorage instance, or null if Web Storage is NOT supported.

getSessionStorage

public static StorageExt getSessionStorage()

Returns a Session Storage.

Returns:

the sessionStorage instance, or null if Web Storage is NOT supported.

addStorageChangeHandler

public com.google.web.bindery.event.shared.HandlerRegistration addStorageChangeHandler(StorageChangeEvent.Handler handler)

Registers an event handler for StorageChangeEvent

Parameters:

handler - an event handler instance

Returns:

HandlerRegistration used to remove this handler

clear

public void clear()

Removes all items in the Storage, and its cache if activated

See Also:

W3C Web Storage - Storage.clear()

clearCache

public void clearCache()

Clear all cached serialized object from configured StorageCache

containsKey

public <T> boolean containsKey(StorageKey<T> key)

Test if this storage contains a value for the specified key.

StorageKeyFactory is preferred to get a StorageKey instance for primitive types.

Type Parameters:

T - the type of stored value

Parameters:

key - the key whose presence in this storage is to be tested

Returns:

true if this storage contains a value for the specified key.

get

public <T> T get(StorageKey<T> key)
          throws com.google.gwt.user.client.rpc.SerializationException

Returns the value in the Storage associated with the specified key, or null if this Storage contains no mapping for the key.

Note : Deserialization will be performed to return a correct value type.
StorageKeyFactory is preferred to get a StorageKey instance for primitive types.

Type Parameters:

T - the type of stored value

Parameters:

key - the key to a value in the Storage

Returns:

the value associated with the given key

Throws:

com.google.gwt.user.client.rpc.SerializationException

See Also:

W3C Web Storage - Storage.getItem(k)

getString

public String getString(String key)

Get directly the stored string value associated with the specified key.

Note : No deserialization will be performed

Parameters:

key - the key to a value in the Storage

Returns:

the stored string value associated with the given key

See Also:

W3C Web Storage - Storage.getItem(k)

key

public String key(int index)

Returns the key at the specified index.

Parameters:

index - the index of the key

Returns:

the key at the specified index in this Storage

See Also:

W3C Web Storage - Storage.key(n)

put

public <T> void put(StorageKey<T> key,
                    T value)
             throws com.google.gwt.user.client.rpc.SerializationException,
                    StorageQuotaExceededException

Store the specified value with the specified key in this storage.

Note: null value is not allowed.
If the storage previously contained a mapping for the key, the old value is replaced.
StorageKeyFactory is preferred to get a StorageKey instance for primitive types.

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Throws:

com.google.gwt.user.client.rpc.SerializationException

StorageQuotaExceededException

remove

public <T extends Serializable> void remove(StorageKey<T> key)

Removes the record for the specified key from this storage if present.

StorageKeyFactory is preferred to get a StorageKey instance for primitive types

Type Parameters:

T - the type of stored value

Parameters:

key - key whose mapping is to be removed from the map

setEventLevel

public void setEventLevel(StorageChangeEvent.Level eventLevel)

Set Event Level.

Note : set to StorageChangeEvent.Level.STRING, will prevent the deserialization process in event creation,
This matters only if the old value (object value) is wanted in every storage change event.

Parameters:

eventLevel - the event detail level

See Also:

StorageChangeEvent

size

public int size()

Returns the number of items in this Storage.

Returns:

number of items in this Storage

See Also:

W3C Web Storage - Storage.length()