百度Mp3的API在windows phone 7中的使用

最近重新写了一个音乐的播放器。其中用到了百度音乐的API：http://cloud21.iteye.com/blog/611914

由于百度MP3的API的地址和我们请求的到得XML文件都是GB2312编码的。所以遇到了点麻烦。好了废话不说，上代码。

namespace BaiduAPI_test
{
    public partial class MainPage : PhoneApplicationPage
    {
        // Constructor
        public MainPage()
        {
            InitializeComponent();
        }
        public class MusicUpdateState
        {
            public HttpWebRequest AsyncRequest { get; set; }
            public HttpWebResponse AsyncResponse { get; set; }
        }
        private void btn_search_Click(object sender, RoutedEventArgs e)
        {
            //string gb_songname = utf_8_to_gb2312(SongName.Text);
            //string gb_singername = utf_8_to_gb2312(SingerName.Text);

            //由于百度的地址是用GB2312编码的，所以要用HttpUtility.UrlEncode这个函数来编码
            string songname = HttpUtility.UrlEncode(SongName.Text);
            string singername = HttpUtility.UrlEncode(SingerName.Text);

            string Uri = "http://box.zhangmen.baidu.com/x?op=12&count=1&title=" + songname + "$$" + singername + "$$$$";

            UriBuilder fullUri = new UriBuilder(Uri);
            HttpWebRequest musicRequest = (HttpWebRequest)WebRequest.Create(fullUri.Uri);

            MusicUpdateState musicState = new MusicUpdateState();
            musicState.AsyncRequest = musicRequest;
            musicRequest.BeginGetResponse(new AsyncCallback(HandleMusicResponse), musicState);
        }

        private void HandleMusicResponse(IAsyncResult asyncResult)
        {
            MusicUpdateState musicState = (MusicUpdateState)asyncResult.AsyncState;
            HttpWebRequest musicRequest = (HttpWebRequest)musicState.AsyncRequest;
            musicState.AsyncResponse = (HttpWebResponse)musicRequest.EndGetResponse(asyncResult);

            Stream streamResult;
            string encode = "";
            string decode = "";
            streamResult = musicState.AsyncResponse.GetResponseStream();
            //这里也是一样的，请求得到的XML是用GB2312编码的，直接用XmlReader读取Stream的话会提示系统不支持GB2312编码
            var sr = new StreamReader(streamResult);
            string srResult = sr.ReadToEnd();

            //----Test----------

            //Dispatcher.BeginInvoke(() =>
            //    {
            //        tb_decode.Text = srResult;
            //    });

            using (XmlReader reader = XmlReader.Create(new StringReader(srResult)))
            {
                reader.ReadToFollowing("encode");
                encode = reader.ReadElementContentAsString();

                //百度地址中间的数字是7位或者8位的，所以要判断最后一个是不是数字
                string encodeUrl = encode.Substring(44,8);
                string lastNumberUri = IsNumber(encodeUrl);

                reader.ReadToFollowing("decode");
                decode = reader.ReadElementContentAsString();

                UriBuilder fullUri = new UriBuilder("http://zhangmenshiting.baidu.com/data/music/" + lastNumberUri + "/" + decode);
                Dispatcher.BeginInvoke(() =>
                    {
                        BaiduMusicElement.Source = fullUri.Uri;
                        BaiduMusicElement.AutoPlay = true;
                        BaiduMusicElement.Position = TimeSpan.FromMilliseconds(0);
                        BaiduMusicElement.Play();
                    });
            }
        }
        private string IsNumber(string str)
        {//判断str的最后一个字符是否数字
            int result;
            string lastOne = str.Substring(7);
            if (int.TryParse(lastOne, out result))
            {
                return str;
            }
            else
            {
                return str.Substring(0, 7);
            }
        }
        
    }
}