extjs combobox怎么向服务器传值

extjs combobox如何向服务器传值
我是个combobox初学者我的代码如下

JScript code

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        })    });});

JScript code

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);    }});