r MenuBar = {
			refresh: function(){
				console.log( '刷新菜单目录' );
			}
		};
		var SubMenu = {
			add: function(){
				console.log( '增加子菜单' );
			},
			del: function(){
				console.log( '删除子菜单' );
			}
		};
		在让button 变得有用起来之前，我们要先把这些行为都封装在命令类中：
		var RefreshMenuBarCommand = function( receiver ){
			this.receiver = receiver;
		};
		RefreshMenuBarCommand.prototype.execute = function(){
			this.receiver