JSon传值

$("#login").click(function () {
               if ($('#userId').val() != "" && $('#pwdId').val() != "") {
                   $.ajax({
                       type: 'Post',
                       async: false,
                       url: 'Login.aspx/loginYN',
                       data: "{'username':'" + $('#userId').val() + "','password':'" + $('#pwdId').val() + "'}",
                       contentType: "application/json; charset=utf-8",
                       dataType: "json",
                       success: function (msg) {
                           if (msg.d == "1") {
                               window.location.href = 'admin/index.aspx';
                           } else {
                               alert("用户名或密码错误!");
                           }
                       },
                       error: function (err) {
                           alert("登录失败！请稍后再试或联系管理员。");
                       }
                   });
               }
               else {
                   alert("请输入用户名或密码！");
               }
           });

后台部分：

[WebMethod]
    public static string loginYN(string username, string password)
    {
        tb_admin lg = new tb_admin();
        lg._username = username.Trim();
        lg._password = FormsAuthentication.HashPasswordForStoringInConfigFile(password.Trim(), "MD5");
        return b_login.loginYN(lg);
    }