extjs 调用webservice返回json类型

 function Btn_Search()
   {
        var div=document.getElementById("EditTable");
        div.innerHTML="";
       
        Ext.Ajax.request({
                       url:'WebService.asmx/GeneralList',
                       method:'POST',
                       jsonData:{UserName:""},
                       //headers:{'Content-Type':'application/json;utf-8'},
                       success:General,
                       failure:On_Error
                    });
   }

                                      {name: 'UserID', type: 'string'},
                                             {name: 'LogonName', type: 'string'} ,
                                             {name: 'UserName', type: 'string'},
                                             {name: 'Password', type: 'string'},
                                             {name: 'dtDateTime', type: 'string'} 
                                          ]);
                                                               
     var data=Ext.util.JSON.decode(result.responseText);    
     //alert(result.responseText);

    //先看返回的result.responseText是不是json,如果是，就用data.d来取数据
     var store=new Ext.data.Store({
                                    proxy:new Ext.data.MemoryProxy(data.d),   //先看返回的result.responseText是不是json,如果是，就用data.d来取数据
                                    reader:new Ext.data.JsonReader({
                                              fields:[{name:'UserID',type:'int'},
                                                      {name:'LogonName',type:'string'},
                                                      {name:'UserName',type:'string'},
                                                      {name:'Password',type:'string'},
                                                      {name:'dtDateTime',type:'string',dateFormat:'Y-m-d'},
                                                      {name:'Email',type:'string'}
                                                      ]})
                                  });
     // store.load();
    //var record=store.getAt(0);
    //alert(record.get("dtDateTime"));

web.config需要配置

<?xml version="1.0"?>
<!--
    Note: As an alternative to hand editing this file you can use the
    web admin tool to configure settings for your application. Use
    the Website->Asp.Net Configuration option in Visual Studio.
    A full list of settings and comments can be found in
    machine.config.comments usually located in
    \Windows\Microsoft.Net\Framework\v2.x\Config
-->
<configuration>
 <appSettings/>
 <connectionStrings/>
 <system.web>
  <!--
            Set compilation debug="true" to insert debugging
            symbols into the compiled page. Because this
            affects performance, set this value to true only
            during development.
        -->
  <compilation debug="false">
   <assemblies>
    <add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/></assemblies></compilation>
  <!--
            The <authentication> section enables configuration
            of the security authentication mode used by
            ASP.NET to identify an incoming user.
        -->
  <authentication mode="Windows"/>
  <!--
            The <customErrors> section enables configuration
            of what to do if/when an unhandled error occurs
            during the execution of a request. Specifically,
            it enables developers to configure html error pages
            to be displayed in place of a error stack trace.

        <customErrors mode="RemoteOnly" defaultRedirect="GenericErrorPage.htm">
            <error statusCode="403" redirect="NoAccess.htm" />
            <error statusCode="404" redirect="FileNotFound.htm" />
        </customErrors>
        -->   
    <httpHandlers>
      <remove verb="*" path="*.asmx"/>
      <add path="*.asmx" verb="*" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
        validate="false" />
      <add path="*_AppService.axd" verb="*" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
       validate="false" />
      <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" validate="false"/>            
    </httpHandlers>   
    <httpModules>
        <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>           
    </httpModules>   
    <webServices>
      <protocols>
        <add name="HttpPost"/>       
      </protocols>    
    </webServices>
  </system.web>
</configuration>