javascript 实现java中的Map (高效)[转]

javascript实现java中的Map，代码是在国外的一个网站上看到的（http://stackoverflow.com/questions/368280/javascript-hashmap-equivalent ），自己稍作了修改，之前也看到过有人用2个数组实现了Map，但是我感觉效率比较低，现在这个我感觉效率还可以，自己做了下测试，代码如下：
Map.js

function Map(linkItems) {
    
this
.current = undefined;
    
this
._size = 
0
;
    
if
(linkItems === 
false
){
        
this
.disableLinking();
    }
}
/**
 * 获取当前map
 * @return 当前对象
 */
Map.noop = function() {
    
return
 
this
;
};
/**
 * 非法操作
 * @return
 */
Map.illegal = function() {
    
throw
 
new
 Error(
"非法操作，Map已经被禁用"
);
};
/**
 *
 * @param obj
 * @param foreignKeys
 * @return
 */
Map.from = function(obj, foreignKeys) {
    var map = 
new
 Map;
    
for
(var prop in obj) {
        
if
(foreignKeys || obj.hasOwnProperty(prop)){
            map.put(prop, obj[prop]);
        }
    }
    
return
 map;
};
/**
 * 禁用map
 * @return
 */
Map.prototype.disableLinking = function() {
    
this
.link = Map.noop;
    
this
.unlink = Map.noop;
    
this
.disableLinking = Map.noop;
    
this
.next = Map.illegal;
    
this
.key = Map.illegal;
    
this
.value = Map.illegal;
    
this
.clear = Map.illegal;
    
return
 
this
;
};
/**
 * 返回hash值 例如：number 123
 * @param value key/value
 * @return
 */
Map.prototype.hash = function(value) {
    
return
 (typeof value) + 
' '
 + (value 
instanceof
 Object ? (value.__hash || (value.__hash = ++arguments.callee.current)) : value.toString());
};
/**
 * 返回map的长度
 * @return
 */
Map.prototype.size = function() {
    
return
 
this
._size;
};

Map.prototype.hash.current = 
0
;
/**
 * 通过key获取value
 * @param key
 * @return
 */
Map.prototype.get = function(key) {
    var item = 
this
[
this
.hash(key)];
    
return
 item === undefined ? undefined : item.value;
};
/**
 * 向map中添加数据
 * @param key 键
 * @param value 值
 * @return
 */
Map.prototype.put = function(key, value) {
    var hash = 
this
.hash(key);
    
if
(
this
[hash] === undefined) {
        var item = { key : key, value : value };
        
this
[hash] = item;
        
this
.link(item);
        ++
this
._size;
    }
else
{
        
this
[hash].value = value;
    }
    
return
 
this
;
};
/**
 * 通过key删除数据
 * @param key
 * @return
 */
Map.prototype.remove = function(key) {
    var hash = 
this
.hash(key);
    var item = 
this
[hash];
    
if
(item !== undefined) {
        --
this
._size;
        
this
.unlink(item);
        delete 
this
[hash];
    }
    
return
 
this
;
};
/**
 * 清除map
 * @return
 */
Map.prototype.clear = function() {
    
while
(
this
._size){
        
this
.remove(
this
.key());
    }
    
return
 
this
;
};
/**
 * 处理队列
 * @param item
 * @return
 */
Map.prototype.link = function(item) {
    
if
(
this
._size == 
0
) {
        item.prev = item;
        item.next = item;
        
this
.current = item;
    }
else
 {
        item.prev = 
this
.current.prev;
        item.prev.next = item;
        item.next = 
this
.current;
        
this
.current.prev = item;
    }
};
Map.prototype.unlink = function(item) {
    
if
(
this
._size == 
0
){
        
this
.current = undefined;
    }
else
 {
        item.prev.next = item.next;
        item.next.prev = item.prev;
        
if
(item === 
this
.current){
            
this
.current = item.next;
        }
    }
};
/**
 * 获取下一个
 * @return
 */
Map.prototype.next = function() {
    
this
.current = 
this
.current.next;
    
return
 
this
;
};
/**
 * 获取key
 * @return
 */
Map.prototype.key = function() {
    
return
 
this
.current.key;
};
/**
 * 获取value
 * @return
 */
Map.prototype.value = function() {
    
return
 
this
.current.value;
};

function Map(linkItems) { 
    this.current = undefined; 
    this._size = 0; 
    if(linkItems === false){
    	this.disableLinking(); 
    } 
}
/**
 * 获取当前map
 * @return 当前对象
 */
Map.noop = function() { 
    return this; 
}; 
/**
 * 非法操作
 * @return
 */
Map.illegal = function() { 
    throw new Error("非法操作，Map已经被禁用"); 
}; 
/**
 * 
 * @param obj
 * @param foreignKeys
 * @return
 */
Map.from = function(obj, foreignKeys) { 
    var map = new Map; 
    for(var prop in obj) { 
        if(foreignKeys || obj.hasOwnProperty(prop)){
        	map.put(prop, obj[prop]); 
        } 
    } 
    return map; 
}; 
/**
 * 禁用map
 * @return
 */
Map.prototype.disableLinking = function() { 
    this.link = Map.noop; 
    this.unlink = Map.noop; 
    this.disableLinking = Map.noop; 
    this.next = Map.illegal; 
    this.key = Map.illegal; 
    this.value = Map.illegal; 
    this.clear = Map.illegal; 
    return this; 
}; 
/**
 * 返回hash值 例如：number 123
 * @param value key/value
 * @return
 */
Map.prototype.hash = function(value) { 
    return (typeof value) + ' ' + (value instanceof Object ? (value.__hash || (value.__hash = ++arguments.callee.current)) : value.toString()); 
}; 
/**
 * 返回map的长度
 * @return
 */
Map.prototype.size = function() { 
    return this._size;
}; 

Map.prototype.hash.current = 0; 
/**
 * 通过key获取value
 * @param key
 * @return
 */
Map.prototype.get = function(key) { 
    var item = this[this.hash(key)]; 
    return item === undefined ? undefined : item.value; 
}; 
/**
 * 向map中添加数据
 * @param key 键
 * @param value 值
 * @return
 */
Map.prototype.put = function(key, value) { 
    var hash = this.hash(key); 
    if(this[hash] === undefined) { 
        var item = { key : key, value : value }; 
        this[hash] = item; 
        this.link(item); 
        ++this._size; 
    }else{
    	this[hash].value = value;
    } 
    return this; 
}; 
/**
 * 通过key删除数据
 * @param key
 * @return
 */
Map.prototype.remove = function(key) { 
    var hash = this.hash(key); 
    var item = this[hash]; 
    if(item !== undefined) { 
        --this._size; 
        this.unlink(item); 
        delete this[hash]; 
    } 
    return this; 
}; 
/**
 * 清除map
 * @return
 */
Map.prototype.clear = function() { 
    while(this._size){
		this.remove(this.key()); 
	} 
    return this; 
}; 
/**
 * 处理队列
 * @param item
 * @return
 */
Map.prototype.link = function(item) { 
    if(this._size == 0) { 
        item.prev = item; 
        item.next = item; 
        this.current = item; 
    }else { 
        item.prev = this.current.prev; 
        item.prev.next = item; 
        item.next = this.current; 
        this.current.prev = item;
    } 
}; 
Map.prototype.unlink = function(item) { 
    if(this._size == 0){ 
        this.current = undefined;
    }else { 
        item.prev.next = item.next; 
        item.next.prev = item.prev; 
        if(item === this.current){
        	this.current = item.next; 
        } 
    } 
}; 
/**
 * 获取下一个
 * @return
 */
Map.prototype.next = function() { 
    this.current = this.current.next; 
    return this;
}; 
/**
 * 获取key
 * @return
 */
Map.prototype.key = function() { 
    return this.current.key; 
}; 
/**
 * 获取value
 * @return
 */
Map.prototype.value = function() { 
    return this.current.value; 
}; 

测试代码如下：

var l=
10000
;
    var map=
new
 Map();
    var start=
new
 Date().getTime();
    
for
(var i=
0
;i<l;i++){
        map.put(
"key_"
+i,
new
 Date());
    }
    var end=
new
 Date().getTime();
    document.write(
"向map中添加了  "
+l+
" 个Date对象.........."
);
    document.write(
"<br/>"
);
    document.write(
"耗时  "
+(end-start)+
" 毫秒，map的长度为："
+map.size());
    document.write(
"<br/>"
);
    document.write(
"在map中提取全部数据.........."
);
    document.write(
"<br/>"
);
    start=
new
 Date().getTime();
    
for
(var i=
0
;i<map.size();i++){
        map.get(
"key_"
+i).getTime();
    }
    end=
new
 Date().getTime();
    document.write(
"耗时  "
+(end-start)+
" 毫秒"
);
    document.write(
"<br/>"
);
    document.write(
"清空map.........."
);
    document.write(
"<br/>"
);
    start=
new
 Date().getTime();
    map.clear();
    end=
new
 Date().getTime();
    document.write(
"耗时  "
+(end-start)+
" 毫秒，map的长度为："
+map.size());
    document.write(
"<br/>"
);

var l=10000;
	var map=new Map();
	var start=new Date().getTime();
	for(var i=0;i<l;i++){
		map.put("key_"+i,new Date());
	}
	var end=new Date().getTime();
	document.write("向map中添加了  "+l+" 个Date对象..........");
	document.write("<br/>");
	document.write("耗时  "+(end-start)+" 毫秒，map的长度为："+map.size());
	document.write("<br/>");
	document.write("在map中提取全部数据..........");
	document.write("<br/>");
	start=new Date().getTime();
	for(var i=0;i<map.size();i++){
		map.get("key_"+i).getTime();
	}
	end=new Date().getTime();
	document.write("耗时  "+(end-start)+" 毫秒");
	document.write("<br/>");
	document.write("清空map..........");
	document.write("<br/>");
	start=new Date().getTime();
	map.clear();
	end=new Date().getTime();
	document.write("耗时  "+(end-start)+" 毫秒，map的长度为："+map.size());
	document.write("<br/>");

测试结果如下：
1.IE7



2.Firefox 3.6.8



3.谷歌浏览器5.0



方法next的使用：

var map=
new
 Map();
    map.put(
"key_1"
,
"value_1"
);
    map.put(
"key_2"
,
"value_2"
);
    map.put(
"key_3"
,
"value_3"
);
    var m=map.next();
    document.write(
"map.next:key="
+m.key()+
" value="
+m.value());
    document.write(
"<br/>"
);
    m=map.next();
    document.write(
"map.next:key="
+m.key()+
" value="
+m.value());

var map=new Map();
	map.put("key_1","value_1");
	map.put("key_2","value_2");
	map.put("key_3","value_3");
	var m=map.next();
	document.write("map.next:key="+m.key()+" value="+m.value());
	document.write("<br/>");
	m=map.next();
	document.write("map.next:key="+m.key()+" value="+m.value());

结果如下：

map.next:key=key_2 value=value_2
map.next:key=key_3 value=value_3