类似查询mysql数据库的查询XML的JS类

一个快捷操作XML数据库的Javascript接口对象，包含select、count、tables、fields等方法，能够像操作mysql等其它数据库一样操作XML数据库。

 if(document.implementation.hasFeature("XPath","3.0")){ //浏览器bug修复
    XMLDocument.prototype.selectNodes=function(cXPathString,xNode){
       if(!xNode){xNode=this;}
       var oNSResolver=this.createNSResolver(this.documentElement);
       var aItems=this.evaluate(cXPathString, xNode, oNSResolver,XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
       var aResult=[];
       for(var i=0;i< aItems.snapshotLength;i++){
          aResult[i]=aItems.snapshotItem(i);
       }
       return aResult;
    }
    Element.prototype.selectNodes=function(cXPathString){
       if(this.ownerDocument.selectNodes){
          return this.ownerDocument.selectNodes(cXPathString,this);
       }else{throw "For XML Elements Only";}
    }
 }
 /*
 jQuery版本要求:1.7.2
 XML数据库查询类,实现的方法
 load(pt,async):
 loadFromText(xStr):
 select(tb,data,where,order,limit,group);
 count(tb,where);
 tables();
 fields(tb);
 */
 function xml_db(pt,async){
     var _root=this,async=typeof(async)!="undefined"?async:true;
     _root.dbObj=null;/*数据库对象数组*/
     _root.status=false;/*数据库对象数组*/
     _root.dbpath=typeof(pt)!="undefined"?pt:false;/*数据库路径*/
   _root.ifAutoPara=true;

   var autoPara=function(para,oriParas){/*自动附加参数*/
         if(para.length >2){
            for(var i=2;i< para.length;i++){
               if(para[i].match(/^\s*where/i)){oriParas['where']=para[i];}
               if(para[i].match(/^\s*order/i)){oriParas['order']=para[i];}
               if(para[i].match(/^\s*limit/i)){oriParas['limit']=para[i];}
               if(para[i].match(/^\s*group/i)){oriParas['group']=para[i];}
            }
         }
   },
   WOLG=function(str,kw,oriParas){/*附加参数*/
           if(typeof(str)!="undefined"){
         var reg=new RegExp("^"+kw+"\\s*","ig"),ky=kw.replace(/\s+\w+/gi,"");
         str=str.replace(reg,"");
         oriParas[ky]=kw+" "+str;
           }
   },
   decode=function(string,quote_style){/*解码*/
         var optTemp=0,i=0,noquotes=false;
         if(typeof quote_style === 'undefined'){quote_style=2;}
         string=string.toString().replace(/</g, '<').replace(/>/g, '>');
         var OPTS={'ENT_NOQUOTES': 0,'ENT_HTML_QUOTE_SINGLE': 1,'ENT_HTML_QUOTE_DOUBLE':2,'ENT_COMPAT':2,'ENT_QUOTES':3,'ENT_IGNORE':4};
         if(quote_style===0){noquotes=true;}
         if(typeof quote_style !== 'number'){
         quote_style=[].concat(quote_style);
         for(i=0; i < quote_style.length; i++){
           if(OPTS[quote_style[i]] === 0){
               noquotes=true;
           }else if(OPTS[quote_style[i]]){
               optTemp=optTemp | OPTS[quote_style[i]];
           }
         }
         quote_style=optTemp;
         }
         if(quote_style & OPTS.ENT_HTML_QUOTE_SINGLE){
         string=string.replace(/�*39;/g, "'");
         string=string.replace(/'|�*27;/g, "'");
         }
         if(!noquotes){string=string.replace(/"/g, '"');}
         string=string.replace(/&/g, '&');
         return string;
   },
   xQuery=function(str,node){
       return  typeof(node)!="undefined"? node.selectNodes(str):_root.dbObj.selectNodes(str);
   };

   _root.load=function(pt,async){
        var pt=typeof(pt)!="undefined"?pt:_root.dbpath,
            async=typeof(async)!="undefined"?async:true;
      jQuery.ajax({
            'type': "GET",
               'url':pt,
               'dataType':'text',
               'cache': false,
               'async': async,
               'success': function(dt){
                     var root=_root.loadFromText(dt.replace(/[\r\n]+/gmi,"").replace(/<!--.*?-->/gi,"").replace(/>\s+/gi,">"));
                     if(root){
                       _root.dbObj=root.documentElement;
                     }
               }
             });
   };

   _root.loadFromText=function (xStr){
       try{
             if(window.DOMParser){
               parser=new DOMParser();
               txmlDoc=parser.parseFromString(xStr,"text/xml");
             }else{
               txmlDoc=new ActiveXObject("Microsoft.XMLDOM");
               txmlDoc.async="false";
               txmlDoc.loadXML(xStr);
             }
             _root.status=txmlDoc.documentElement?true:false;
             return _root.status?txmlDoc:false;
         }catch(e){
       _root.status=false;
       return false;
         }
   };

   _root.query=function(){

   };

   _root.select=function(tb,data,where,order,limit,group){
       if(!_root.status){return false;}
       var addtion={},data=typeof(data)=="undefined"?"*":data;
     if(!_root.ifAutoPara){ /*自动附加参数*/
        autoPara(arguments,addtion);
     }else{
        WOLG(where,"where",addtion);
        WOLG(order,"order by",addtion);
        WOLG(limit,"limit",addtion);
        WOLG(group,"group by",addtion);
     }

     if(typeof(addtion['where'])=="undefined"){
         addtion['where']="where `id`>=0";
     }
     addtion['where']=addtion['where'].replace(/&&/gi," and ").replace(/\|\|/gi," or ");
     addtion['where']=addtion['where'].replace(/^\s*where\s*/gi,"");

     var fdArr=_root.fields(tb),sFdArr,reg=new RegExp(),oArr,rArr=[];/*相关变量定义*/

     if(data!="*"){
       sFdArr=jQuery.grep(
           jQuery.type(data)=="array"?data:data.split(/\s*,\s*/gi),function(n,i){
           return jQuery.inArray(n,fdArr)!=-1;
           });
       if(!sFdArr.length){return false;}
       if(jQuery.inArray("id",sFdArr)==-1){sFdArr.push("id");}
     }
     jQuery.each(fdArr,function(i,n){
         reg.compile('`'+n+'`',"gi");
       addtion['where']=addtion['where'].replace(reg,"v"+i);
     });
     oArr=xQuery("//root/"+tb+"/it["+addtion['where']+"]");
     jQuery.each(oArr,function(i,n){
       var orArr={};
       jQuery.each(n.childNodes,function(dx,cNode){
         var curVL=jQuery(cNode).text();
         curVL=curVL.match(/^\d+$/,"gi")?parseInt(curVL):(curVL.match(/^\d+\.\d+$/,"gi")?parseFloat(curVL):decode(curVL));
         if(data=="*"){
           orArr[fdArr[dx]]=curVL;
         }else if(jQuery.inArray(fdArr[dx],sFdArr)!=-1){
           orArr[fdArr[dx]]=curVL;
         }
       });
       rArr.push(orArr);
     });

     if(typeof(addtion['order'])!="undefined"){
       if(addtion['order'].match(/^\s*order\s+by\s+`?(\w+)`?\s+(asc|desc)\s*$/gi)){
           var orders=[];
         orders[0]=(jQuery.inArray(RegExp.$1.toString(),fdArr)!=-1)?RegExp.$1.toString():"id";
         orders[1]=(jQuery.inArray(RegExp.$2.toString(),["desc","asc"])!=-1)?RegExp.$2.toString():"desc";
         rArr.sort(function(a,b){
            var ca=0,cb=0;
            if(a[orders[0]].toString().match(/^\d+$/gi)&&b[orders[0]].toString().match(/^\d+$/gi)){
              ca=parseInt(a[orders[0]]);cb=parseInt(b[orders[0]]);
            }else if(a[orders[0]].toString().match(/^\d+\.\d+$/gi)&&b[orders[0]].toString().match(/^\d+\.\d+$/gi)){
              ca=parseFloat(a[orders[0]]);cb=parseFloat(b[orders[0]]);
            }else{
              ca=a[orders[0]];cb=b[orders[0]];
            }
            if(ca==cb)return 0;
                     if(orders[1].toLowerCase()=='asc'){
                       return (ca > cb)? 1 : -1;
                     }else{
                         return (ca < cb)? 1 : -1;
                     }
         });
       }
     };
     if(typeof(addtion['limit'])!="undefined"){
       if(addtion['limit'].match(/^\s*limit\s+(\d+)\s*,\s*(\d+)\s*$/gi)){
         var itemsnum=rArr.length,snum=parseInt(RegExp.$1),lenum=parseInt(RegExp.$2);
         snum=(snum < 0) ? 0:(snum < itemsnum ? snum : (itemsnum-1));
                 rArr2=[];
                 for(var i=0;i< itemsnum;i++){
                     if(i >= snum && i <= (snum+lenum-1)){
                       rArr2.push(rArr[i]);
                     }
                 }
                 return rArr2;
       }
     }
     return rArr;
   };

   _root.count=function(tb,where){
       if(!_root.status){return false;}
     var fdArr=_root.fields(tb),reg=new RegExp(),addtion={};
     WOLG(where,"where",addtion);
     if(typeof(addtion['where'])=="undefined"){
         addtion['where']="where `id`>=0";
     }
     addtion['where']=addtion['where'].replace(/&&/gi," and ").replace(/\|\|/gi," or ");
     addtion['where']=addtion['where'].replace(/^\s*where\s*/gi,"");
     jQuery.each(fdArr,function(i,n){
         reg.compile('`'+n+'`',"gi");
       addtion['where']=addtion['where'].replace(reg,"v"+i);
     });
     return xQuery("//root/"+tb+"/it["+addtion['where']+"]").length;
   };

   _root.fields=function(tb){
       if(!_root.status){return false;}
     var tbInfo=xQuery('//root/'+tb);
     return tbInfo.length >0 ? tbInfo[0].getAttribute("fd").split("|"):[];
   };

   _root.tables=function(){
       if(!_root.status){return false;}
       var tbArr=[];
     jQuery.each(xQuery('//root')[0].childNodes,function(dx,n){
       tbArr.push(n.tagName);
     });
     return tbArr;
   }

   if(_root.dbpath!==false){
     _root.load(_root.dbpath,async);
   }

 }

XML数据库文件格式（文件名为：db.xml）：

<?xml version="1.0" encoding="UTF-8"?>
<root>
 <menu fd="id|name|mtype|level|year|major">
  <it>
   <v0>1</v0>
   <v1>云南财经大学</v1>
   <v2></v2>
   <v3>专升本</v3>
   <v4>3年</v4>
   <v5>工商管理</v5>
  </it>
  <it>
   <v0>2</v0>
   <v1>云南财经大学</v1>
   <v2></v2>
   <v3>专升本</v3>
   <v4>3年</v4>
   <v5>会计学</v5>
  </it>
  <it>
   <v0>3</v0>
   <v1>云南财经大学</v1>
   <v2></v2>
   <v3>专升本</v3>
   <v4>3年</v4>
   <v5>金融学</v5>
  </it>
  <it>
   <v0>4</v0>
   <v1>云南财经大学</v1>
   <v2></v2>
   <v3>高升专</v3>
   <v4>3年</v4>
   <v5>法律事务</v5>
  </it>
 </menu>
</root>

　　

使用方法介绍:

var dbObj=new xml_db("db.xml",false);
var data=dbObj.select("menu","id,name,major","where `major`!='金融学'","limit 0,2","order by `id` desc");
for(var i=0;i< data.length;i++){
 document.write(i+"->id:"+data[i]['id']+" name:"+data[i]['name']+" major:"+data[i]['major']+"<br/>");
}

输出：
0->id:1 name:云南财经大学 major:工商管理
1->id:2 name:云南财经大学 major:会计学 
其它方法说明：
tables():返回所有表的数组；
fields(tb):返回表名为tb的所有字段名；
count(tb,where):返回表tb中符合where条件的记录数量