js實現接口的幾種方式

Javascript模仿接口能夠有三種方式：1.註釋法 2.檢查屬性法 3.鴨式辨形法 

1.註釋法:此方法屬於程序文檔範疇，對接口的繼承實現徹底依靠程序員自覺

/*
   interface People{
         function createHead();
         function createBody();
   }
*/
var woman = function(name){   //implements People interface
    this.name = name;
}
woman.prototype.showName = function(){
    alert(this.name);
}
woman.prototype.createBody = function(){  //實現必要的方法
    alert("身體已經建立好");
}
woman.prototype.createHead = function(){
    alert("頭部已經建立好");
}

 

//2.屬性檢查法：把要實現的接口方法添加到類屬性列表裏，經過定義好的檢測反覆檢查是否已經實現了那些方法
//優缺點：能夠強迫程序員實現接口，沒實現就報錯。不過雖然聲明瞭本身實現了哪些方法，但實現時極可能有遺漏

/*
interface People{
    function createHead();
    function createBody();
}
*/
var woman = function(name){
    this.name = name;
    this.implementsInterfaces = ['People'];
}
woman.prototype.showName = function(){
    alert(this.name);
}
woman.prototype.createBody = function(){  //實現必要的方法
    alert("身體已經建立好");
}
woman.prototype.createHead = function(){
    alert("頭部已經建立好");
}

function implement(obj,interfaces){
    for(var i=1;i<interfaces.length;i++){
        var interfaceName = interfaces[i];
        var interfaceFound = false;
        for(var j=0;j<obj.implementsInterfaces.length;j++){
            if(obj.implementsInterfaces[j] = interfaceName){
                 interfaceFound = true;
                 break;
            }
        }
        if(!interfaceFound){
              return false;
        }
    }
    return true;
}

function  isImplememts(instance,interfaces){    //判斷對象是否已經繼承相應接口
    if(!implement(instance,interfaces)){
        throw new Error("Object doesn't implement a required interface");
    }
}

 

3.鴨式辨型法：（不經過外表判斷鴨子，而經過其是否有鴨子的特性來判斷。如James Whitcomb Riley所說，像鴨子同樣走路而且嘎嘎叫的就是鴨子）
上面倆種都聲明瞭本身實現了那些接口，其實聲明不重要，實現接口核心的是類實現了接口方法集。若是類具備了接口定義的全部方法函數名相同的函數，那麼認爲它實現了接口

//接口類，用來建立接口
var Interface = function(name,motheds){
    if(agruments.length!=2){
        throw new Error("Interface constructor called with "+arguments.length+"arguments,but expected exactly 2");
    }
    this.name = name;
    this.methods = [];
    for(var i=0;i<motheds.length;i++){
        if(typeof motheds[i] !== 'string'){
            throw new Error('Interface constructor expects mothed names to be'+'passes in as a string');
        }
        this.methods.push(motheds[i]);
    }
}
Interface.prototype.ensureImplements = function(objs){
    if(agruments.length != 1){
        throw new Error("Interface constructor called with "+arguments.length+"arguments,but expected exactly 1")
    }
    for(var i=0;i<objs.length;i++){
         var obj = objs[i];
         for(var j=0;j<this.motheds.length;j++){
               var mothed = this.methods[j];
               if(!obj[mothed] || !typeof obj[mothed] !== 'function'){
                    throw new Error('Function Interface.ensureImplements:implements interface'+this.name+',obj.mothed'+mothed+'was not found');
               }
         }
    }
}
//建立接口
var People = new Interface('People',['createHead','createBody']);
//子類
var Woman = function(name){
    this.name = name;
    this.implementsInterfaces = ['People'];
}
Woman.prototype.showName = function(){
    alert(this.name);
}
Woman.prototype.createBody = function(){  //實現必要的方法
    alert("女人身體已經建立好");
}
Woman.prototype.createHead = function(){
    alert("女人頭部已經建立好");
}
//子類
var Man = function(name){
    this.name = name;
    this.implementsInterfaces = ['People'];
}
Man.prototype.showName = function(){
    alert(this.name);
}
Man.prototype.createBody = function(){  //實現必要的方法
    alert("男人身體已經建立好");
}
Man.prototype.createHead = function(){
    alert("男人頭部已經建立好");
}
//判斷是否實現
Poeple.ensureImplements(['Woman','Man']);