[WebMethod]

public string IsCorret(string  userName , string userPassWord) {

    if (userName.Equals("cjx") && userPassWord.Equals(""))

    {

        return "True";

    }

    else

    {

        return "False";

    }

}

TextView tvUser = null;

TextView tvPassWord = null;

protected override void OnCreate(Bundle bundle)

{

    base.OnCreate(bundle);

    SetContentView(Resource.Layout.Login);

    Button button = FindViewById<Button>(Resource.Id.into);

    button.Click += (sender, e) => {

        UserService.UserWebService us = new UserService.UserWebService();

        //webservice调用完成后触发

        us.IsCorretCompleted += new UserService.IsCorretCompletedEventHandler(us_IsCorretCompleted);

        tvUser = FindViewById<TextView>(Resource.Id.accountNumber1);

        tvPassWord = FindViewById<TextView>(Resource.Id.password);

        us.IsCorretAsync(tvUser.Text, tvPassWord.Text);

    };

}

void us_IsCorretCompleted(object sender, UserService.IsCorretCompletedEventArgs e)

{

    if (e.Result.Equals("True"))

    {

        //设置一个意图

        var intent = new Intent(this, typeof(MainActivity));

        StartActivity(intent);

    }

    else {

        Toast.MakeText(this, "登录失败！", ToastLength.Short).Show();

    }

}