JavaScript命令模式原理与用法实例详解

 function manager() {
        this.addFlow=function (id,value) {
            //1.得到目标节点
          var div=document.getElementById("div01");
          var newFlow=document.createElement("div");
          newFlow.setAttribute("id",id);
          newFlow.innerHTML=value;
          div.appendChild(newFlow);

        }
    }

 manager.prototype.extcute=(function () {
      /*command 命令对象
      * */
      return function (command) {
        return this[command.method](command.id,command.value);
      }

    })();

 var ma = new manager();//可以用该对象，调用其的东西
      //用于存储"调用对象命令的"集合
      var commands = new Array();
      //集合的游标--初始化在末尾
      var index = commands.length;

 var API=function () {
   this.addFlow=function () {
     //把调用封装起来
     var command={
       method:"addFlow",
       id:new UUID().createUUID(),//产生id的插件
       value:document.getElementById("flow").value
     };
     //把调用对象保存起来,用于回退和重做作用
     commands.push(command);
     //重新定位游标---赋值记录
     index = commands.length;
     //调用
     ma.extcute(command);
   };
   /**
    * 用于返回的方法
    */
   this.ret=function () {
     if(index-1<0){
       alert("已经到了最后一步了...");
     }else {
       var all=document.getElementById("div01").childNodes;
       document.getElementById("div01").removeChild(all[all.length-1]);
       index=index-1;
     }
   };
   /**
    * 用于重做的方法
    */
   this.again=function () {
     if(index>=commands.length){
       alert("已经到了最前面一步了,不能进行重做...");
     }else {
       var command=commands[index];//获取当前的命令位置
       ma.extcute(command);
       index=index+1;
     }
   }
 }

API=new API();//实例化

//添加支持ctrl+z--返回
key("ctrl+z",function () {

  API.ret();
});
//重做---
key("ctrl+shift+x",function () {
  API.again();

})

/*

uuid.js - Version 0.2
JavaScript Class to create a UUID like identifier

Copyright (C) 2006-2008, Erik Giberti (AF-Design), All rights reserved.

This program is free software; you can redistribute it and/or modify it under 
the terms of the GNU General Public License as published by the Free Software 
Foundation; either version 2 of the License, or (at your option) any later 
version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY 
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A 
PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with 
this program; if not, write to the Free Software Foundation, Inc., 59 Temple 
Place, Suite 330, Boston, MA 02111-1307 USA

The latest version of this file can be downloaded from
http://www.af-design.com/resources/javascript_uuid.php

HISTORY:
6/5/06   - Initial Release
5/22/08 - Updated code to run faster, removed randrange(min,max) in favor of
     a simpler rand(max) function. Reduced overhead by using getTime() 
     method of date class (suggestion by James Hall).

KNOWN ISSUES:
- Still no way to get MAC address in JavaScript
- Research into other versions of UUID show promising possibilities 
 (more research needed)
- Documentation needs improvement

*/

// On creation of a UUID object, set it's initial value
function UUID(){
  this.id = this.createUUID();
}

// When asked what this Object is, lie and return it's value
UUID.prototype.valueOf = function(){ return this.id; }
UUID.prototype.toString = function(){ return this.id; }

//
// INSTANCE SPECIFIC METHODS
//

UUID.prototype.createUUID = function(){
  //
  // Loose interpretation of the specification DCE 1.1: Remote Procedure Call
  // described at http://www.opengroup.org/onlinepubs/009629399/apdxa.htm#tagtcjh_37
  // since JavaScript doesn't allow access to internal systems, the last 48 bits 
  // of the node section is made up using a series of random numbers (6 octets long).
  // 
  var dg = new Date(1582, 10, 15, 0, 0, 0, 0);
  var dc = new Date();
  var t = dc.getTime() - dg.getTime();
  var h = '-';
  var tl = UUID.getIntegerBits(t,0,31);
  var tm = UUID.getIntegerBits(t,32,47);
  var thv = UUID.getIntegerBits(t,48,59) + '1'; // version 1, security version is 2
  var csar = UUID.getIntegerBits(UUID.rand(4095),0,7);
  var csl = UUID.getIntegerBits(UUID.rand(4095),0,7);

  // since detection of anything about the machine/browser is far to buggy, 
  // include some more random numbers here
  // if NIC or an IP can be obtained reliably, that should be put in
  // here instead.
  var n = UUID.getIntegerBits(UUID.rand(8191),0,7) + 
      UUID.getIntegerBits(UUID.rand(8191),8,15) + 
      UUID.getIntegerBits(UUID.rand(8191),0,7) + 
      UUID.getIntegerBits(UUID.rand(8191),8,15) + 
      UUID.getIntegerBits(UUID.rand(8191),0,15); // this last number is two octets long
  return tl + h + tm + h + thv + h + csar + csl + h + n; 
}


//
// GENERAL METHODS (Not instance specific)
//


// Pull out only certain bits from a very large integer, used to get the time
// code information for the first part of a UUID. Will return zero's if there 
// aren't enough bits to shift where it needs to.
UUID.getIntegerBits = function(val,start,end){
  var base16 = UUID.returnBase(val,16);
  var quadArray = new Array();
  var quadString = '';
  var i = 0;
  for(i=0;i= base) var output = this.returnBase(MSD,base) + convert[LSD];
    else var output = convert[MSD] + convert[LSD];
  }
  return output;
}

// pick a random number within a range of numbers
// int b rand(int a); where 0 <= b <= a
UUID.rand = function(max){
  return Math.floor(Math.random() * max);
}

// end of UUID class file