function loadXml(str) {
  if (str == null) {
   return null;
  }
  var doc = str;
  try{
   doc = createXMLDOM();
   doc.async = false;
   doc.loadXML(str);
  }catch(e){
   doc = $.parseXML(str);
  }
  return doc;
}

/**
*xml对象转json对象
*xmlObj:xml对象
*nodename:节点路径('ROOT/ITEM')
*isarray:true,强制返回数组对象
**/
function xmltojson(xmlObj,nodename,isarray){
   var obj=$(xmlObj);
   var itemobj={};
   var nodenames="";
   var getAllAttrs=function(node){//递归解析xml 转换成json对象
      var _itemobj={};
      var notNull=false;
      var nodechilds=node.childNodes;
      var childlenght=nodechilds.length;
      var _attrs=node.attributes;
      var firstnodeName="#text";
      try{
        firstnodeName=nodechilds[0].nodeName;
      }catch(e){}
      if((childlenght>0&&firstnodeName!="#text")||_attrs.length>0){
         var _childs=nodechilds;
         var _childslength=nodechilds.length;
         var _fileName_="";
         if(undefined!=_attrs){
           var _attrslength=_attrs.length;
           for(var i=0; i<_attrslength; i++){//解析xml节点属性
            var attrname=_attrs[i].nodeName;
            var attrvalue=_attrs[i].nodeValue;
            _itemobj[attrname]=attrvalue;
           }
         }
       for (var j = 0; j < _childslength; j++) {//解析xml子节点
          var _node = _childs[j];
          var _fildName = _node.nodeName;
          if("#text"==_fildName){break;};
          if(_itemobj[_fildName]!=undefined){//如果有重复的节点需要转为数组格式
            if(!(_itemobj[_fildName] instanceof Array)){
              var a=_itemobj[_fildName];
              _itemobj[_fildName]=[a];//如果该节点出现大于一个的情况 把第一个的值存放到数组中
            }
          }
          var _fildValue=getAllAttrs(_node);
          try{
            _itemobj[_fildName].push(_fildValue);
          }catch(e){
            _itemobj[_fildName]=_fildValue;
            _itemobj["length"]=1;
          }
         }
      }else{
        _itemobj=(node.textContent==undefined)?node.text:node.textContent;
      }
      return _itemobj;
    };
   if(nodename){
    nodenames=nodename.split("/")
   }
   for(var i=0;i<nodenames.length;i++){
     obj=obj.find(nodenames[i]);
   }
   $(obj).each(function(key,item){
     if(itemobj[item.nodeName]!=undefined){
       if(!(itemobj[item.nodeName] instanceof Array)){
         var a=itemobj[item.nodeName];
         itemobj[item.nodeName]=[a];
       }
       itemobj[item.nodeName].push(getAllAttrs(item));
     }else{
       if(nodenames.length>0){
         itemobj[item.nodeName]=getAllAttrs(item);
       }else{
         itemobj[item.firstChild.nodeName]=getAllAttrs(item.firstChild);
       }
     }
   });
   if(nodenames.length>1){
     itemobj=itemobj[nodenames[nodenames.length-1]];
   }
   if(isarray&&!(itemobj instanceof Array)&&itemobj!=undefined){
     itemobj=[itemobj];
   }
  return itemobj;
};

var xmlstr="<USERS>" +
        "<USER state='0'>" +
        "<USERNAME type='String'>张三</USERNAME>" +
        "<USERID type='String'>00001</USERID>" +
        "</USER>" +
        "<USER state='1'>" +
        "<USERNAME type='String' size='100'>李四</USERNAME>" +
        "<USERID>00002</USERID>" +
        "</USER>" +
        "<USER>" +
        "<USERNAME>李四</USERNAME>" +
        "<USERID>00002</USERID>" +
        "</USER>" +
        "</USERS>";
var xmlobj=loadXml(xmlstr);

{
  "USERS": {
    "USER": [
      {
        "state": "0",
        "USERNAME": {
          "type": "String"
        },
        "length": 1,
        "USERID": {
          "type": "String"
        }
      },
      {
        "state": "1",
        "USERNAME": {
          "type": "String",
          "size": "100"
        },
        "length": 1,
        "USERID": "00002"
      },
      {
        "USERNAME": "李四",
        "length": 1,
        "USERID": "00002"
      }
    ],
    "length": 1
  }
}

[
  {
   "state": "0",
   "USERNAME": {
     "type": "String"
   },
   "length": 1,
   "USERID": {
     "type": "String"
   }
  },
  {
   "state": "1",
   "USERNAME": {
     "type": "String",
     "size": "100"
   },
   "length": 1,
   "USERID": "00002"
  },
  {
   "USERNAME": "李四",
   "length": 1,
   "USERID": "00002"
  }
]