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