学步园

首先我们要明白，接口其实就是强制一个类实现所有它定义的函数；这也就意味着，接口的实现其根本就在于：有效的检测实现类是否实现所有接口

我翻阅了Pro Javascript Design Pattern，其对于Javascript接口中的缺点有着深刻的理解：接口使用中的最大的问题在于，无法强迫其他程序员遵守你定义的接口

Java，c#，PHP都比较类似，如下即Java中接口的实现：

Student.java:
public interface Student {
      void GetUp();
	  void Breakfast();
	  void Lunch();
	  void Bed();
}

StudentImpl.java:
public class StudentImpl implements Student{

	public static void main(String[] args) {
		StudentImpl sml = new StudentImpl();
		sml.Breakfast();

	}
	public void GetUp() { System.out.println("起床");  }

	public void Breakfast() {	System.out.println("早餐");  }

	public void Lunch() {	System.out.println("午餐");  }

	public void Bed() {	System.out.println("睡觉");  }

}

可以以这种方式实现，思路为：定义一个Interface，通过检测传入的方法是否全部实现，判断接口是否实现，依寻这种方法我们可以采用如下的方式实现：

var Interface = function(className,methodsArray){  
    if(arguments.length!=2){  
        throw new Error("Error Arguments");  
    }  
    this.obj = className;  
    this.methods = []; 
    for(var i=0;i<methodsArray.length;i++){  
        if(typeof methodsArray[i]!=='string'){  
            throw new Error("methodName must be String");  
        }  
        this.methods.push(methodsArray[i]);  
    }  
    this.init();  
}  

Interface.prototype = {  
    init:function(){  
        if(this.obj){  
            for(var i=0;i<this.methods.length;i++){  
                var __tempMethodName__ = this.methods[i];  
                if(!this.obj[__tempMethodName__]){  
                    throw new Error("please implements methods:"+__tempMethodName__);  
                    return false;  
                }  
            }
            console.log("Interface is implemented");  
        }  
        else{  
            throw new Error("class not found");  
        }  
    }  
}

var realizeFun = new Object();  
realizeFun.GetUp = function(){ console.log("起床");  }  
realizeFun.Breakfast = function(){ console.log("早饭");  } 
var inter = new Interface(realizeFun,['GetUp','Breakfast']);   

但是我们是否会有一点别扭的感觉，怎么先定义函数&实现接口，再绑定接口呢？这样会导致接口和实现类之间的高耦合，可以改写上面的方法减小耦合：

var realizeFun = new Object();  
realizeFun.GetUp = function(){ console.log("起床");  }  
realizeFun.Breakfast = function(){ console.log("早饭");  } 
var inter = new Interface(realizeFun,['GetUp','Breakfast']);  

var Interface = function(methodsArray){  
    if(arguments.length!=1){  
        throw new Error("Error Arguments");  
    }    
    this.methods = []; 
    for(var i=0;i<methodsArray.length;i++){  
        if(typeof methodsArray[i]!=='string'){  
            throw new Error("methodName must be String");  
        }  
        this.methods.push(methodsArray[i]);  
    }    
}  

Interface.prototype= {
	ensureImplents : function(Interimpl)
	{ 
       if(Interimpl){  
            for(var i=0;i<this.methods.length;i++){  
                var __tempMethodName__ = this.methods[i];  
                if(!Interimpl[__tempMethodName__]){  
                    throw new Error("please implements methods:"+__tempMethodName__);  
                    return false;  
                }  
            }
            console.log("Interface is implemented");  
	    } 
   }
}

var inter = new Interface(['GetUp','Breakfast']);
var realizeFun = {};  
realizeFun.GetUp = function(){ console.log("起床");  }  
realizeFun.Breakfast = function(){ console.log("早饭");  } 
inter.ensureImplents(realizeFun);

参考文献：Pro Javascript Design Pattern