<script type="text/javascript">
/**name-->接口名称
 * methods-->接口的方法签名
 */
var Interface = function(name, methods) {
    if(arguments.length != 2) {
        throw new Error("创建接口"+name+"时，传入参数个数为：" + arguments.length
          + ", 实际需要两个参数.");
    }
    
    this.name = name;
    this.methods = [];
    for(var i = 0, len = methods.length; i < len; i++) {
        if(typeof methods[i] !== 'string') {
            throw new Error("方法名称必须是String类型.");
        }
        this.methods.push(methods[i]);        
    }    
};    

/**校验object是否实现了指定的接口
 * object-->接口的实现类
 */
Interface.ensureImplements = function(object) {
    if(arguments.length < 2) {
        throw new Error("ensureImplements方法验证时必须传入待验证的接口");
    }

    for(var i = 1, len = arguments.length; i < len; i++) {
        var interface = arguments[i];
        if(interface.constructor !== Interface) {
            throw new Error("传入的参数类型错误，必须为Interface类型。");
        }
        
        for(var j = 0, methodsLen = interface.methods.length; j < methodsLen; j++) {
            var method = interface.methods[j];
            if(!object[method] || typeof object[method] !== 'function') {
                throw new Error("在实现类中没有找到" + method 
                                + "方法。该类必须实现" +interface.name + "接口的" + method + "方法");
            }
        }
    } 
};

//定义ResultSet接口
var ResultSet = new Interface('ResultSet', ['save','update','del']);
var SelectInterface = new Interface('SelectInterface', ['select']);

var User = function(object){
	Interface.ensureImplements(object, ResultSet, SelectInterface);
	this.object = object;
};

User.prototype.oop = function(){
	this.object.save();
	this.object.update();
	this.object.del();
	this.object.select();
};

/**
 *定义Obj类，实现ResultSet接口的全部方法
 */
function Obj(){}
Obj.prototype = {
	save : function(){
		alert("Obj-->save()方法");
	},
	update : function(){
		alert("Obj-->update()方法");
	},
	del : function(){
		alert("Obj-->del()方法");	
	},
	select : function(){
		alert("Obj-->select()方法");	
	}
}
/**
 *定义Obj1类，实现ResultSet接口的全部方法
 */
function Obj1(){}
Obj1.prototype = {
	save : function(){
		alert("Obj1-->save()方法");
	},
	update : function(){
		alert("Obj1-->update()方法");
	},
	del : function(){
		alert("Obj1-->del()方法");	
	}
}

var obj = new Obj();
var user = new User(obj);
user.oop();
obj = new Obj1();
user = new User(obj);
user.oop();
</script>