JavaScript设计模式-18.享元模式 

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>javascript高级语法18-享元模式</title>
</head>
<body>
<script>
 
/*享元模式是一个为了 提高性能（空间复杂度）的设计模式；
 * 他使用于程序会生产大量的相类似的对象时 耗用大量内存的问题；
 * 
 */
 
function demo(){
//有一个城市要进行汽车登记
  /*
 * 制造商，型号，日期，所有者，车牌号，最近一次登记
 */
var Car = function(make,model,year,owner,tag,renewDate){
this.make = make
this.model = model;
this.year = year
this.owner = owner
this.tag = tag
this.renewDate = renewDate;
this.getMake = function(){
return this.make;
}
 
}
// 装饰者，计算函数运行时间
var simpleProfiler2 = function(component){
this.component = component;
this.action = function(methodName){
var self= this;
var method = component[methodName];
//如果是函数那就进行装饰
if(typeof method == "function"){
var startDate = new Date().getTime();
method.apply(self.component,arguments);
var endDate = new Date().getTime();
alert(endDate - startDate);
}
}
}
 
//北京4150000全部要登记
var ca = new Array();
function addCar(){
this.begin = function(){
for(var i=0;i<4150000;i++){
ca.push(new Car("东风","雪铁龙","2017-5-16","张丹",
"京AM39385","2016-12-12"));
}
}
}
new simpleProfiler2(new addCar()).action("begin");
//耗费了大量时间和内存占用
}
// demo();
 
 function xiangyuan(){
  //1.内在状态
  var Car = function(make,model,year,owner,tag,renewDate){
this.make = make
this.model = model;
this.year = year;
this.getMake = function(){
return this.make;
}
 
}
  //2.单例模式的简单工厂
  var myCarInfo = function(){
  this.createCar = function(make,model,year,owner,tag,renewDate){
  var c = carInfoFactory(make,model,year);
  c["owner"] = owner;
  c["tag"] = tag;
  c["renewDate"] = renewDate;
  return c;  
  }
  }
  //享元工厂
  var carInfoFactory = (function(){
  var  carInfo = {};
  return function(make,model,year){
  if(carInfo[make+model+year]){
  return carInfo[make+model+year];
  }else{
  var newCar = new Car(make,model,year);
  carInfo[make+model+year] = newCar;
  return newCar;
  }
  }
  })();
 
//北京4150000全部要登记
var test  = new myCarInfo();
var startDate = new Date().getTime();
 var ca = new Array();
 for(var i=0;i<4150000;i++){
  ca.push(test.createCar("东风","雪铁龙","2017-5-16","张丹",
"京AM39385","2016-12-12"));
 }
var endDate = new Date().getTime();
alert(endDate - startDate);
 }
 xiangyuan();
 
</script>
</body>
</html>

 

posted @ 2017-07-16 21:11  橙云生  阅读(174)  评论(0)    收藏  举报