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该内容是在网上找的　只是将ｄａｔａ修改为了动态的而已　Ｏ（∩＿∩）Ｏ～

 

ｊｓｐ　　页面：

 

行业：<select id="myselect"> </select>
     <script language=javascript type="text/javascript">
       var ts = new TreeSelector(document.getElementById("myselect"), data, 0);
       ts.createTree();
     </script>

 

 

ｊｓ：

 

var data = new Array();
   var i=0;
   var temp;
   <c:forEach items="${industries}" var="m"> ／／后台获取的数据库中的数据
   data[i] = {id: '${m.industryId}',pid: '${m.superiorIndustry}',text: '${m.industryName}'};
   i=i+1; 
   </c:forEach>
 function TreeSelector(item, data, rootId) {
        this._data = data;
        this._item = item;
        this._rootId = rootId;
        this._item.options.add(new Option('无', -1));//如果是顶级目录
      }
  
     TreeSelector.prototype.createTree = function() {
        var len = this._data.length;//获取数据的长度
        for (var i = 0; i < len; i++) {
          if (this._data[i].pid == this._rootId) {
            this._item.options.add(new Option(this._data[i].text, this._data[i].id));
            for (var j = 0; j < len; j++) {
              this.createSubOption(len, this._data[i], this._data[j]);
            }
          }
        }
      }

     TreeSelector.prototype.createSubOption = function(len, current, next) {
        var blank = "";
        if (next.pid == current.id) {
          intLevel = 0;
          var intlvl = this.getLevel(this._data, this._rootId, current);
          for (a = 0; a <= intlvl; a++) blank += "....";
          this._item.options.add(new Option(blank + next.text, next.id));
          for (var j = 0; j < len; j++) {
            this.createSubOption(len, next, this._data[j]);
          }
        }
      }

     TreeSelector.prototype.getLevel = function(datasources, topId, currentitem) {
        var pid = currentitem.pid;
        if (pid != topId) {
          for (var i = 0; i < datasources.length; i++) {
            if (datasources[i].id == pid) {
              intLevel++;
              this.getLevel(datasources, topId, datasources[i]);
            }
          }
        }
        return intLevel;
      }