extjs combobox怎么向服务器传值

Ext.require([
    'Ext.form.ComboBox',
    'Ext.tip.QuickTips',
    'Ext.data.*'
]);
Ext.onReady(function() {
    Ext.tip.QuickTips.init();
    // Define the model for a State
    Ext.regModel('State', {
        fields: [
            {type: 'string', name: 'xh'},
            {type: 'string', name: 'xm'}
        ]
       
    });

    // The data for all states
   
    // The data store holding the states; shared by each of the ComboBox examples below
//    var store = new Ext.data.Store({
//        model: 'State',
//        data: states
//    });

    var comboxStore = new Ext.data.Store({ 
         model: 'State',         
         proxy: { 
             type:'ajax', 
              actionMethods: {
             create : 'POST',
             read   : 'POST',
             update : 'POST',
             destroy: 'POST'},
             url: "http://localhost:8080/cjcx/servlet/Getcj?Method=GetAllxhxm" , 
             reader:'json'         
         }, 
             atuoLoad:false            
         } ); 
//    comboxStore.load();

    // ComboBox with a custom item template
    var simple = new Ext.form.ComboBox({
        fieldLabel: '请输入您的姓名',
        renderTo: 'simple',
        displayField: 'xm',   
        valueField: 'name', 
//        hiddenValue:'xh',
//        hiddenField:'xh',
       // hiddenName:'empUserNum',
        allowBlank : false, 
        width: 500,
        labelWidth: 130,
        hideTrigger:true,
//        typeAhead:true,//延时查询，与下面的参数配合
//        typeAheadDelay:250,//默认250
         blankText:'输入姓名查询成绩',
         emptyText:'输入姓名查询成绩', 
         listEmptyText:'请仔细核对姓名信息',
         minChars : 1,          
         store:  comboxStore,
         query:'remote',   
         queryParam : 'empUserNum', 
//         hiddernName : 'empUserNum',        
         getInnerTpl: function() {
            return '<div ext:qtip="{xh}"> {xm}</div>';
            
       }
    });
  
     ////// Collapsible code panels; ignore: /////

    Ext.select('pre.code').each(function(pre) {
        new Ext.form.FieldSet({
            contentEl: pre,
            renderTo: pre.parent(),
            title: 'View code for this example',
            collapsible: true,
            collapsed: true
        })
    });

});

userForm.form.doAction('submit', {
    url : 'user!saveUser.action',
    method : 'post',
    params : '',
    success: function(form, action) {
        if (action.result.message == "success")
        {
            Ext.Msg.alert("Information", "save success");
        } else
        {
            Ext.Msg.alert("Information", "save fail," + action.result.message);
        }                                       
    },
    failure: function(form, action) {        
         Ext.Msg.alert("Information", "save_fail," + action.result.message);
    }
});