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<meta charset="UTF-8">
<title>javascript 高级语法16-装饰者模式</title>
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<script>
/*通过需求引出装饰者模式
*
*/ //接口
var Interface = function(name,methods){
if(arguments.length != 2){
alert("interface must have two paramters...");
}
this.name = name;//这个是接口的名字
this.methods = [];//定义个空数组来转载函数名
for (var i = 0; i < methods.length; i++) {
if(typeof methods[i] != "string"){
alert("method name must is String ...")
}else{
this.methods.push(methods[i])
}
}
}
//定义接口的一个静态方法来实现接口与实现类的直接检验
//静态方法不要写成Interface.prototype.* 因为这是写到接口原型连上的
//我们要把静态的函数直接写到类层次上
Interface.ensureImplements = function(object){
if(arguments.length<2){
alert("必须最少是2个参数");
return false;
}
//遍历
for (var i = 1; i < arguments.length; i++) {
var inter = arguments[i];
//如果你是接口就必须是Interface类型的
if(inter.constructor != Interface){
throw new Error("if is interface class must is Interface type");
}
//遍历函数集合并分析
for (var j = 0; j < inter.methods.length; j++) {
var method = inter.methods[j];
//实现类中必须有方法名字 和 接口中所有的方法名项目
if(!object[method] || typeof object[method] != "function"){
throw new Error("实现类并没有完全实现接口中的所有方法...");
}
}
}
} function demo(){
//汽车店的接口
var CarShop = new Interface("CarShop",["getPrice","assemble"]);
var myCarShop = function(){
this.getPrice = function(){
document.write(15000+"<br>");
}
this.assemble = function(){
document.write("汽车组装..."+"<br>")
}
Interface.ensureImplements(this,CarShop);
} var jimCarShop = new myCarShop();
jimCarShop.getPrice();
jimCarShop.assemble();
document.write("--------------------"+"<br>") /*新需求：
* 汽车还会有附属产品 音响 (k),真皮沙发(M),保险杠(N)
* 每一个附属的产品会影响到汽车的组装和其价格
* 你能想到什么办法？
*/ //改写接口
var CarShop2 = new Interface("CarShop2",["getPrice","assemble","addK","addM","addN"]);
var myCarShop2 = function(){
var price = 150000;
this.getPrice = function(){
document.write(price+"<br>")
}
this.assemble = function(){
document.write("汽车组装"+"<br>")
}
this.addK = function(){
price += 1000;
}
this.addM = function(){
price += 2000;
}
this.addN = function(){
price += 3000;
}
Interface.ensureImplements(this,CarShop2);
} var jimCarShop2 = new myCarShop2();
jimCarShop2.addK();
jimCarShop2.addM();
jimCarShop2.addN();
jimCarShop2.getPrice();
jimCarShop2.assemble(); /*好像能成功，但是新的问题来了
* 你把接口全改了，可是我继承本接口的类不一定全要有音响，沙发，保险杠。
* 难道我要改变所有实现本接口的实现类吗？
* 显然是不对的。
*/
//2.如果不改变接口，那我就增加子类
var CarShop = new Interface("CarShop",["getPrice","assemble"]);
var myCarShop = function(){
this.getPrice = function(){
document.write(150000+"<br>");
}
this.assemble = function(){
document.write("汽车组装..."+"<br>")
}
Interface.ensureImplements(this,CarShop);
}
var myCarShopM = function(){
this.getPrice = function(){
document.write(150100+"<br>");
}
this.assemble = function(){
document.write("汽车组装..."+"<br>")
}
Interface.ensureImplements(this,CarShop);
}
var myCarShopK = function(){
this.getPrice = function(){
document.write(150200+"<br>");
}
this.assemble = function(){
document.write("汽车组装..."+"<br>")
}
Interface.ensureImplements(this,CarShop);
}
//这种方式走不通
/*装饰者的概念和用法：
* 装饰者可以为对象添加新的特性
* 透明的把对象包装在具有相同接口的新对象中
*/ }
// demo();
function decorator(){
//装饰者模式来解决需求
var CarShop = new Interface("CarShop",["getPrice","assemble"]);
//目标对象
var myCarShop = function(){
this.getPrice = function(){
return 150000;
}
this.assemble = function(){
document.write("汽车组装...<br>");
}
Interface.ensureImplements(this,CarShop);
}
//装饰类
var M = function(carshop){
this.getPrice = function(){
return 1000 + carshop.getPrice();
}
this.assemble = function(){
document.write("M组装...<br>");
}
Interface.ensureImplements(this,CarShop);
}
var K = function(carshop){
this.getPrice = function(){
return 2000 + carshop.getPrice();
}
this.assemble = function(){
document.write("k组装...<br>");
}
Interface.ensureImplements(this,CarShop);
}
var N = function(carshop){
this.getPrice = function(){
return 3000 + carshop.getPrice();
}
this.assemble = function(){
document.write("N组装...<br>");
}
Interface.ensureImplements(this,CarShop);
} //调用 var car =new K(new M(new myCarShop()));
alert(car.getPrice());
car.assemble();
}
decorator();
</script>
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