jquery调用webservice

1.给webserver加 [System.Web.Script.Services.ScriptService]标签
如:

Code
[WebService(Namespace = "http://abc.org.cn/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService]
public class user : System.Web.Services.WebService
{
    [WebMethod]
    public bool CheckPwd(string name,string pwd)
    {
        return SchoolMIS.Sys.User.UserFactiory.GetUser().CheckPwd(name, pwd);
    }

}

2.js

   $(
         function ()
        {
             function  WebService(url,pars,callback)
            { 
                $.ajax
                ({ 
                    async : false ,
                    data:pars, 
                    url: url, 
                    type:  " POST " , 
                    contentType:  " application/json;utf-8 " , 
                    dataType: ' json ' , 
                    cache:  false , 
                    success:  function (json){ 
                        callback(json);
                    },
                    beforeSend: function (xml)
                    { 
                         if ( ! pars) 
                        {
                            xml.setRequestHeader( " Content-Type " ,  " application/json;utf-8 " )
                        } 
                    },
                    error: function (xml,status)
                    { 
                         if (status == ' error ' )
                        { 
                             try
                            { 
                                 var  json  =  eval( ' ( '   +  xml.responseText  +   ' ) ' ); 
                                alert( ' Err: '   +  json.Message + ' \n ' + json.StackTrace); 
                            }
                             catch (e)
                            {} 
                        }
                         else
                        { 
                            alert( ' Err: '   +  status); 
                        } 
                    }                           
                });
            }
            
            $( " #btnLogin " ).click
            (
                 function ()
                {
                    var  n,p,r;
                    n = $( " #txtUsername " ).val();
                    p = $( " #txtPassword " ).val();
                     if (n.length == 0   ||  p.length == 0 )
                    {
                        alert( " Please input user name and password. " );
                        $( " #txtUsername " )[ 0 ].focus();
                         if (n.length > 0 )
                            $( " #txtPassword " )[ 0 ].focus();
                          return   false ;
                    }
                    WebService(
                         " user.asmx/Login " ,
                         " {name:' "   +  n  +   " ',pwd:' "   +  p  +   " '} " ,
                         function (jason)
                        {
                             if ( ! jason)
                            {
                                alert( " User name or password error,please retry. " );
                                $( " #txtPassword " )[ 0 ].focus();
                                r  =   false ;
                            }
                             else
                            {
                                r  =   true ;
                            }
                        }
                    );
                     if (r)
                        window.location.href = " /MainForm.aspx " ;
                     return   false ;
                }            
            )
        }
    )