原文在这里：
http://forum.openlaszlo.org/showthread.php?p=25458#post25458
部分摘录如下：
-----------------------------------------------
localcache.lzx
-----------------------------------------------
<library>
<!---
* LocalCache
*
* A dictionary for localy cached data.
* It allows an application to maintain state or to enable the app
* to provide a user with an interface to create a list of keys
* and save and load data for each key,
* essentially creating a temporary local file store
* of xml documents or datasets
*
* We have APP_NAME and CACHE_VER constants
* that we use to version the keysets locally
* so that anytime that an app needs to make a change
* to the local datastructure it can bump up the version
* to avoid datastructure version problems between instances in the wild
* the appname is so that different apps from the same domain
* and which use the same code, don't step on each other's data
*
* expected use for maintaining application state
* // oninit
* if (gLocalCache.testWriteable())
* if(gLocalCache.checkLocalKey("mysavedstate"))...{
* mydata=gLocalCache.getLocalData("mydataname");
* // create LzDataElement with mydata
* } else ...{
* // create key and initialize with data
* gLocalCache.saveLocalKey("mydataname");
* gLocalCache.saveLocalData("mydataname", ds_state.serialize());
* }
* } else ...{
* // deal with the case where local data has been disabled
* }
*
-->
<!-- CONSTANTS -->
<script>
var APP_NAME ="app";
var CACHE_VER = "1";
</script>
<!-- CLASSES -->
<script>
<![CDATA[
//--------------------------------------------------------------------------------
// LocalCache Constructor
//--------------------------------------------------------------------------------
function LocalCache() ...{
// Debug.write("created");
}
LocalCache.prototype = new Object();
LocalCache.prototype.constructor = LocalCache;
Object.registerClass("LocalCache", LocalCache);
//--------------------------------------------------------------------------------
// testWriteable
//--------------------------------------------------------------------------------
LocalCache.prototype.testWriteable = function()...{
var retval = true;
var tstWriteObj = SharedObject.getLocal("tst");
if(!tstWriteObj.flush(10000)) ...{
// local cache is disabled
retval = false;
}
delete tstWriteObj;
return retval;
}
//--------------------------------------------------------------------------------
// saveLocalKeyDataPair
//--------------------------------------------------------------------------------
LocalCache.prototype.saveLocalKeyDataPair = function(key, data)...{
if (this.testWriteable())...{
if (this.checkLocalKey(key))...{
this.saveLocalData(key,data);
return "Saved the data, overwriting anything that was there";
} else ...{
this.saveLocalKey(key);
this.saveLocalData(key,data);
return "Created the key and saved the data.";
}
} else ...{
return "The user has disabled the local shared object";
}
}
//--------------------------------------------------------------------------------
// getLocalData
//--------------------------------------------------------------------------------
LocalCache.prototype.getLocalData = function(key)...{
var localObj = SharedObject.getLocal( APP_NAME+CACHE_VER);
return localObj.data[key];
}
//--------------------------------------------------------------------------------
// getLocalKeys
//--------------------------------------------------------------------------------
LocalCache.prototype.getLocalKeys = function()...{
var localObj = SharedObject.getLocal( APP_NAME+CACHE_VER);
return localObj.data.keys;
}
//--------------------------------------------------------------------------------
// saveLocalKey
//--------------------------------------------------------------------------------
LocalCache.prototype.saveLocalKey = function(key)...{
var localObj = SharedObject.getLocal( APP_NAME+CACHE_VER);
if(localObj.data.keys == null) ...{
localObj.data.keys = new Array(key);
} else ...{
if( this.checkLocalKey(key))...{
// then it already exists
} else ...{
localObj.data.keys.push(key);
localObj.data[key] = "";
}
}
localObj.flush();
delete localObj;
}
//--------------------------------------------------------------------------------
// checkLocalKey
//--------------------------------------------------------------------------------
LocalCache.prototype.checkLocalKey = function(key)...{
var localObj = SharedObject.getLocal( APP_NAME+CACHE_VER);
var len = localObj.data.keys.length;
var retval = false;
for(i=0; i<len; i++)...{
if(localObj.data.keys[i] == key)...{
// it exists
retval = true;
}
}
return retval;
}
//--------------------------------------------------------------------------------
// deleteLocalKey
//--------------------------------------------------------------------------------
LocalCache.prototype.deleteLocalKey = function(key)...{
var localObj = SharedObject.getLocal( APP_NAME+CACHE_VER);
var len = localObj.data.keys.length;
// delete the data if it exists first
this.deleteLocalData(key);
// then find and remove the key from the list
for(i=0; i<len; i++)...{
if(localObj.data.keys[i] == key)...{
localObj.data.keys.splice(i,1);
}
}
localObj.flush();
delete localObj;
}
//--------------------------------------------------------------------------------
// saveLocalData
//--------------------------------------------------------------------------------
LocalCache.prototype.saveLocalData = function(key, data)...{
var localObj = SharedObject.getLocal( APP_NAME+CACHE_VER);
localObj.data[key] = data;
localObj.flush();
delete localObj;
}
//--------------------------------------------------------------------------------
// deleteLocalData
//--------------------------------------------------------------------------------
LocalCache.prototype.deleteLocalData = function(key)...{
var localObj = SharedObject.getLocal( APP_NAME+CACHE_VER);
delete localObj.data[key];
localObj.flush();
delete localObj;
}
]]>
</script>
<!-- INITIALIZATION -->
<script>
var gLocalCache = new LocalCache();
</script>
</library>
---------------------------------------------------------------
saveselectionsample.lzx
--------------------------------------------------------------
<canvas>
<debug y="700" width="750" height="175"/>
<include href="localcache.lzx"/>
<dataset name="dsselection1">
<items>
<item value="item1">item one</item>
<item value="item2">item two</item>
<item value="item3">item three</item>
<item value="item4">item four</item>
</items>
</dataset>
<dataset name="dsselection2">
<items>
<item value="item1">item one</item>
</items>
</dataset>
<view name="interface">
<simplelayout axis="y"/>
<view name="buttons" >
<wrappinglayout axis="y"/>
<button text="saveSelections" >
<method event="onclick">
<![CDATA[
var dp = dsselection1.getPointer();
// we should maintain a variable for the first check that fails and use that
// instead of calling checkLocalKey each time or the user will get the dialog box
// each time if they've disabled it and want to keep it disabled.
if(gLocalCache.checkLocalKey("dsselections"))...{
gLocalCache.saveLocalKeyDataPair("dsselections", dp.serialize());
} else ...{
// at this point local shared objects must be disabled or the key would exist
// from the initial call of loadSelections
// nevertheless we might want to reinitialize it here
// in case the user has changed their settings
// durring the session from disabled to enabled
// gLocalCache.saveLocalKeyDataPair("dsselections", dp.serialize());
}
]]>
</method>
</button>
<button text="loadSelections" >
<method event="onclick">
<![CDATA[
var dp = dsselection2.getPointer();
if(gLocalCache.checkLocalKey("dsselections"))...{
// Debug.write("localdata exits");
var selCacheNode = LzDataNode.stringToLzData(gLocalCache.getLocalData ("dsselections" ))
dsselection2.setChildNodes([selCacheNode.getFirstChild()]);
// Debug.write("loaded and serialized:"+ dp.serialize());
} else ...{
// Debug.write("--in-else-lso-needs-initializing--" );
gLocalCache.saveLocalKeyDataPair("dsselections", dp.serialize());
}
]]>
</method>
</button>
</view>
<combobox id="gogocombo1" editable="false">
<textlistitem name="textguy1"
datapath="dsselection1:/items/item"
text="gogo" />
</combobox>
<combobox id="gogocombo2" editable="false">
<textlistitem name="textguy2"
datapath="dsselection2:/items/item"
text="gogo gadget" />
</combobox>
</view>
</canvas>
该例子后面有评价认为，如果有多个用户同时使用一个browser，那么他们有可能共享相同的shareobject，除非在shareobject中区分用户，而且这个临时数据在某一个用户清空缓存的时候清掉所有的临时数据，所以还是局限性。
免责声明：本文为网络用户发布，其观点仅代表作者个人观点，与本站无关，本站仅提供信息存储服务。文中陈述内容未经本站证实，其真实性、完整性、及时性本站不作任何保证或承诺，请读者仅作参考，并请自行核实相关内容。
