windows phone异步调用api

直接上代码
private void chaxunbutton1_Click(object sender, RoutedEventArgs e)
{

        string s =textBox1.Text;


        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("http://300report.jumpw.com/api/getrole?name=" + HttpUtility.UrlEncode(s));


        request.Method = "GET";
        HttpWebResponse response = request.GetResponse();

        StreamReader sr = new StreamReader(response.GetResponseStream());
        string jsonstr = sr.ReadLine();

        JObject jo = (JObject)JsonConvert.DeserializeObject(jsonstr);

        if (jo["Result"].ToString() == "OK")
        {
            textBlock1.Text=("角色名称：" + jo["Role"]["RoleName"].ToString());
            textBlock2.Text = ("角色等级：" + jo["Role"]["RoleLevel"].ToString());
            textBlock3.Text = ("节操值：" + jo["Role"]["JumpValue"].ToString());
            textBlock4.Text = ("胜场数：" + jo["Role"]["WinCount"].ToString());
            textBlock5.Text = ("总场数：" + jo["Role"]["MatchCount"].ToString());
        }
        else
        {
            textBlock3.Text = ("读取英雄信息失败！");
        }


    }
}

}
求大神把他改成异步调用

http://www.cnblogs.com/SanMaoSpace/archive/2011/07/27/2118133.html
http://www.uml.org.cn/c%2B%2B/201305231.asp （第三个代码）