extjs4.1下拉框 及二级联动

 //岗位的名称
  Ext.regModel('Units', {
  fields: [{type:'string',name:'UnitID'},{type:'string',name:'UnitName'}]
 });
  var unitStore = Ext.create('Ext.data.Store', {
  model: 'Units',
  proxy:{
      type:'ajax',
   url:'/jxkh/app/jsp/jxkh_dafen_Mr.jsp?fg=11&uid='+uId,//查询
   reader:new Ext.data.JsonReader({},[{name:'UnitID'},{name:'UnitName'}])
   }, autoLoad:true
  });
  
      //下级岗位的名称
  Ext.regModel('State', {
   fields: [{type:'string',name:'value'},{type:'string',name:'text'}]
  });
  // The data store holding the states
  var store = Ext.create('Ext.data.Store', {
   model: 'State',
   proxy:{
       type:'ajax',
    url:'/jxkh/app/jsp/jxkh_dafen_Mr.jsp?fg=1',//查询
    reader:new Ext.data.JsonReader({},[{name:'value'},{name:'text'}])
    }
  });
        //store.load();//加载页面时不加载 点击后加载，
  pageVar.toolPanel = Ext.create('Ext.form.Panel',{
   height:45,
   layout:{type:'absolute'},
   region:'north',
   items:[
          {
     id:'comb',
              xtype: 'combo',
              width: 270,
              fieldLabel: ' 岗位',
     listConfig:{
      loadingText:'正在加载信息'
      },
     triggerAction:'all',
     store:unitStore,
        valueField:'UnitID',
              displayField:'UnitName',
              labelAlign:'right',
     queryMode:'remote',
     emptyText:'         全 部    ',
              x: -50,
              y: 10,
              listeners:{   
                select:function(combo, record,index){
                     try{
                         var parent=Ext.getCmp('combo1');
                         parent.clearValue();
                         store.load({params:{ppostid:this.value}});
                     }
                     catch(ex){
                         Ext.MessageBox.alert("错误","数据加载失败。");
                     }
                }
            }
          },
          {
     id:'combo1',
                    xtype: 'combo',
                    width: 260,
                    fieldLabel: ' 下级岗位',
     listConfig:{
      loadingText:'正在加载信息'
      },
                    triggerAction:'all',
                    queryMode: 'local', //这里要修改为local
                    selectOnFocus:true,
                    forceSelection: true,
                    allowBlank:false,
                    editable: true,
     triggerAction:'all',
     store:store,
        valueField:'value',
                    displayField:'text',
                    labelAlign:'right',
     emptyText:'         全 部    ',
                    x: 220,
                    y: 10
                },
                {
     id:'dfd',
                    xtype: 'datefield',
                    fieldLabel: '日期',
                    labelAlign: 'right',
                    format:'Y-m-d',
     value:nowTm,
                    x: 470,
                    y: 10
                },
                {
                    xtype: 'button',
                    width: 80,
                    text: '查询',
     handler:queryBtn,
                    x: 730,
                    y: 10
                }   
   ]
  }); 

--------------------------------返回json格式-----------------------------------

/**
      * 输出查询串
      */
     private void UnitInfoJSON(RSTable rs,HttpServletResponse resp){
      PrintWriter out = null;
   StringBuffer sb = new StringBuffer();
   try
   {
    out = resp.getWriter();
    
    if(rs != null && rs.getRowCount() > 0)
    {
     out.print("[");
     sb.append("[");
     for(int i = 0; i < rs.getRowCount(); i++)
     {
      out.print("{UnitID:'" + rs.getValueAt(i, 0) + "',UnitName:'" + rs.getValueAt(i, 1) + "'}");
      sb.append("{UnitID:'" + rs.getValueAt(i, 0) + "',UnitName:'" + rs.getValueAt(i, 1) + "'}");
      if(i != rs.getRowCount() - 1){
       out.print(",");
       sb.append(",");
      }
     }
     out.print("]");
     sb.append("]");
    }
   }
   catch(IOException e)
   {
    out.print("]");
    sb.append("]");
    e.toString();
   }
     }