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Posted on 2006-09-08 17:47 BennyBao 閱讀(2495) 評論(3) 編輯 收藏 所屬分類: AJAX
在網上看到了有些同志提到了為Ajax的XMLHttpRequest提供一個對象池，也讀了他們給出的實現代碼。感覺不是特別理想，于是模仿apache的commons中的ObjectPool的思路寫了一個簡單的JavaScript版。望指教:
function
?ObjectPool(poolableObjectFactory)?
{
 ????
this
._poolableObjectFactory?
=
?poolableObjectFactory;
????
this
._idlePool?
=
?[];?
????
this
._activePool?
=
?[];?
 }
//
?從對象池中租借一個對象，如果目前沒有可用的空閑對象則通過poolableObjectFactory創建一個
//
?既然是借的，用完記得一定要還哦！
ObjectPool.prototype.borrowObject?
=
?
function
()?
{
????
var
?object?
=
?
null
;
????
var
?idlePool?
=
?
this
._idlePool;
????
var
?factory?
=
?
this
._poolableObjectFactory;
  ????
if
?(idlePool.length?
>
?
0
)?
{
????????object?
=
?idlePool.pop();
 ????}
????
else
?
{
????????object?
=
?factory.makeObject();
????}
????
if
?(object?
!=
?
null
)?
{
????????
this
._activePool.push(object);
????????
if
?(factory.activateObject)?
{
????????????factory.activateObject(object);
????????}
????}
????
return
?object;
}
//
?歸還一個對象
ObjectPool.prototype.returnObject?
=
?
function
(object)?
{
????
function
?indexOf(array,?object)?
{
????????
for
?(
var
?i?
=
?
0
;?i?
<
?array.length;?i
++
)?
{
????????????
if
?(array[i]?
==
?object)?
return
?i;
????????}
????????
return
?
-
1
;
????}
????
if
?(object?
!=
?
null
)?
{
????????
var
?activePool?
=
?
this
._activePool;
????????
var
?factory?
=
?
this
._poolableObjectFactory;????????
????????
var
?i?
=
?indexOf(activePool,?object);
????????
if
?(i?
<
?
0
)?
return
;????????
????????
if
?(factory.passivateObject)?
{
????????????factory.passivateObject(object);
????????}
????????
????????activePool.splice(i,?
1
);
????????
this
._idlePool.push(object);
????}
}
//
?返回當前激活對象的個數
ObjectPool.prototype.getNumActive?
=
?
function
()?
{
????
return
?
this
._activePool.length;
}
//
?返回當前空閑對象的個數
ObjectPool.prototype.getNumIdle?
=
?
function
()?
{
????
return
?
this
._idlePool.length;
}
//
?銷毀對象池及其中的所有對象
//
?如果對象池中的對象需要析構。那么必須實現poolableObjectFactory中的destroyObject方法，同時保證ObjectPool的destroy方法在需要的時候被調用到（例如Window的unload事件中）。
ObjectPool.prototype.destroy?
=
?
function
()?
{
????
var
?factory?
=
?
this
._poolableObjectFactory;
????
function
?returnObject(object)?
{
????????
if
?(factory.passivateObject)?
{
????????????factory.passivateObject(object);
????????}
????}
????
function
?destroyObject(object)?
{
????????
if
?(factory.destroyObject)?
{
????????????factory.destroyObject(object);
????????}
????}
????
????
var
?activePool?
=
?
this
._activePool;
????
for
?(
var
?i?
=
?
0
;?i?
<
?activePool.length;?i
++
)?
{
????????
var
?object?
=
?activePool[i];
????????returnObject(object);
????????destroyObject(object);
????}
????
var
?idlePool?
=
?
this
._idlePool;
????
for
?(
var
?i?
=
?
0
;?i?
<
?idlePool.length;?i
++
)?
{
????????
var
?object?
=
?idlePool[i];
????????destroyObject(object);
????}
????
this
._idlePool?
=
?
null
;?
????
this
._activePool?
=
?
null
;?
????
this
._poolableObjectFactory?
=
?
null
;
}
上面代碼中ObjectPool的構造參數poolableObjectFactory的聲明如下:
//
?注意:?這只是說明，不是真正的代碼！
var
?PoolableObjectFactory?
=
?
{????????
????makeObject:?
function
()?
{}
,?
//
?創建一個新的對象。(必須聲明)????
????
????activateObject:?
function
(object)?
{}
,?
//
?當一個對象被激活時(即被借出時)觸發的方法。(可選)
????
????passivateObject:?
function
(object)?
{}
,?
//
?當一個對象被鈍化時(即被歸還時)觸發的方法。(可選)
????
????destroyObject:?
function
(object)?
{}
?
//
?銷毀一個對象。(可選)????????
}
;
結合XMLHttpRequest創建過程的簡陋示例：
//
?聲明XMLHttpRequest的創建工廠
var
?factory?
=
?
{????????
????makeObject:?
function
()?
{
????????
//
?創建XMLHttpRequset對象
????????
if
?(window.ActiveXObject)
{
????????????
return
?
new
?ActiveXObject(
"
Microsoft.XMLHTTP
"
);
????????}
????????
else
?
{
????????????
return
?
new
?XMLHttpRequest();
????????}
????}
,
????????????
????passivateObject:?
function
(xhr)?
{
????????
//
?重置XMLHttpRequset對象
????????xhr.onreadystatechange?
=
?
{}
;
????????xhr.abort();
????}
}
;
var
?pool?
=
?
new
?ObjectPool(factory);?
//
?創建對象池
//
?
var
?xhr?
=
?pool.borrowObject();?
//
?獲得一個XMLHttpRequest對象
xhr.onreadystatechange?
=
?
function
()?
{
????
if
?(xhr.readyState?
==
?
4
)?
{
????????
//
?
????????pool.returnObject(xhr);?
//
?歸還XMLHttpRequest對象
????}
}
;
xhr.open(method,?url,?
true
);
//
?
最后附上jsUnit的測試用例:
function
?test_pool()?
{
????
var
?factory?
=
?
{
????????counter:?
0
,
????????
????????makeObject:?
function
()?
{
????????????
return
?
{id:?
++
?
this
.counter}
;????????????
????????}
,????????
????????
????????activateObject:?
function
(object)?
{
????????????object.activated?
=
?
true
;
????????}
,
????????
????????passivateObject:?
function
(object)?
{
????????????object.activated?
=
?
false
;????????????
????????}
,
????????
????????destroyObject:?
function
(object)?
{
????????????object.destroyed?
=
?
true
;????????????
????????}
????}
;
????
????
var
?pool?
=
?
new
?ObjectPool(factory);
????
????
//
?borrowObject?object1
????
var
?object1?
=
?pool.borrowObject();
????assertEquals(object1.id,?
1
);
????assertTrue(object1.activated);
????assertEquals(factory.counter,?
1
);
????assertEquals(pool.getNumActive(),?
1
);
????assertEquals(pool.getNumIdle(),?
0
);
????
????
//
?borrowObject?object2
????
var
?object2?
=
?pool.borrowObject();
????assertEquals(object2.id,?
2
);
????assertTrue(object2.activated);
????assertEquals(factory.counter,?
2
);
????assertEquals(pool.getNumActive(),?
2
);
????assertEquals(pool.getNumIdle(),?
0
);
????
????
//
?borrowObject?object3
????
var
?object3?
=
?pool.borrowObject();
????assertEquals(object3.id,?
3
);
????assertTrue(object3.activated);
????assertEquals(factory.counter,?
3
);
????assertEquals(pool.getNumActive(),?
3
);
????assertEquals(pool.getNumIdle(),?
0
);
????
????
//
?returnObject?object2
????pool.returnObject(object2);
????assertFalse(object2.activated);
????assertEquals(factory.counter,?
3
);
????assertEquals(pool.getNumActive(),?
2
);
????assertEquals(pool.getNumIdle(),?
1
);
????
????
//
?returnObject?object3
????pool.returnObject(object3);
????assertFalse(object3.activated);
????assertEquals(pool.getNumActive(),?
1
);
????assertEquals(pool.getNumIdle(),?
2
);
????
????
//
?returnObject?object1
????pool.returnObject(object1);
????assertFalse(object1.activated);
????assertEquals(pool.getNumActive(),?
0
);
????assertEquals(pool.getNumIdle(),?
3
);
????
????
//
?destroy?the?pool
????pool.destroy();
????assertTrue(object1.destroyed);
????assertTrue(object2.destroyed);
????assertTrue(object3.destroyed);
}
下載:
http://www.aygfsteel.com/Files/bennybao/pool.rar
Feedback
# re: 為Ajax的XMLHttpRequest提供對象池(模仿Apache中ObjectPool的實現) 回復 更多評論
2007-02-10 01:46 by
好
# re: 為Ajax的XMLHttpRequest提供對象池(模仿Apache中ObjectPool的實現) 回復 更多評論
2007-02-16 11:18 by
為什么要一個activePool ,沒有什么用處呀,用完了直接push進入idle,用的時候直接從idle中pop,同時把xmlrequest封裝一下,讓他自動來pop和push,用只要給出url和recall就可以了
我的郵箱是zsp007@gmail.com歡迎探討
__reqPool={
idle:[],
new:function(){
var r=this.idle.pop();
if(!r){
if (window.XMLHttpRequest)r=new XMLHttpRequest();
else{
try{r=new ActiveXObject("Msxml2.XMLHTTP");}
catch(e){r=new ActiveXObject("Microsoft.XMLHTTP");}
}
}
return r;
}
open:function(url,recall,error){
var http=this.new();
http.open("GET",url,true);
http.onreadystatechange=function(){
if(http.readyState==4)
{
if(http.status==200)recall(http.responseText.toString());
else if(error) error(http.status,http.responseText.toString());
idle.push(http);
}
};
}
}
# re: 為Ajax的XMLHttpRequest提供對象池(模仿Apache中ObjectPool的實現)[未登錄] 回復 更多評論
2007-02-16 13:57 by
@張沈鵬
activePool確實不是必須的，但是有了activePool之后就可以很方便的知道究竟有多少已激活的Object，或者可以利用一個類似“守護線程”的定時器來監控每個Object的激活時間，以便與實現類似超時之類的功能。
另外需要說明的是，根據我的本意，這里的ObjectPool并不只為XMLHttp設計。
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