【.Net MF网络开发板研究-03】获取雅虎天气(HttpClient示例)
???? ?在上篇文章介紹了Http Server，通過PC上的IE瀏覽器（相當(dāng)于Http client）來訪問開發(fā)板上的Http服務(wù)。這次我們在網(wǎng)絡(luò)開發(fā)板上實(shí)現(xiàn)Http Client，獲取雅虎網(wǎng)站的天氣信息，并把這些信息在LCD上顯示出來。
????? 包含兩部分的代碼，一是通過Http協(xié)議獲取數(shù)據(jù)，二是對獲取的網(wǎng)頁，進(jìn)行XML解析，以期獲取天氣信息。
????? 主程序很簡單，就是web服務(wù)請求和畫面顯示。
?????? public static void Main()
??????? {
??????????? try
??????????? {
??????????????? weather = new yahooWeatherRequest();
??????????????? weather.webRequest();
??????????? }
??????????? catch
??????????? {
??????????????? Debug.Print("Error!");
??????????? }
??????????? WindowsDrawing win = new WindowsDrawing();
??????????? win.Width = SystemMetrics.ScreenWidth;
??????????? win.Height = SystemMetrics.ScreenHeight;
??????????? new Program().Run(win);
??????? }
????? 創(chuàng)建Http請求，并獲取數(shù)據(jù)，相關(guān)代碼如下：
??? ??private byte[] getHttpData(string url)
??????? {
??????????? HttpWebRequest request = HttpWebRequest.Create(url) as HttpWebRequest;
??????????? request.HttpsAuthentCerts = null;
??????????? request.KeepAlive = true;
??????????? WebResponse resp = null;
??????????? Stream respStream = null;
??????????? byte[] bytData = null;
??????????? try
??????????? {
??????????????? resp = request.GetResponse();
??????????? }
??????????? catch (Exception e)
??????????? {
??????????????? Debug.Print("Exception in HttpWebRequest.GetResponse(): " + e.Message.ToString());
??????????????? return null;
??????????? }
?
??????????? if (resp != null)
??????????? {
??????????????? respStream = resp.GetResponseStream();
??????????????? int bytesRead = 0;
??????????????? int totalBytes = 0;
??????????????? respStream.ReadTimeout = 5000;
??????????????? Debug.Print("resp length= " + resp.ContentLength.ToString());
??????????????? if (resp.ContentLength!=-1)
??????????????? {
??????????????????? bytData = new byte[resp.ContentLength];
??????????????????? while (totalBytes < bytData.Length)
??????????????????? {
???????????????????????? bytesRead = respStream.Read(bytData, totalBytes, bytData.Length - totalBytes);
???????????????????????? if (bytesRead == 0)
???????????????????????? {
???????????????????????????? Debug.Print("Error: Received " + totalBytes.ToString() + " Out of " + bytData.Length.ToString());
???????????????????????????? bytData = null;
???????????????????????????? break;
???????????????????????? }
???????????????????????? totalBytes += bytesRead;
???????????????????????? Debug.Print("Bytes Read Now 0: " + bytesRead + " Total: " + totalBytes);
??????????????????? }
??????????????????? return bytData;
??????????????? }
??????????????
??????????? }
??????????? if (respStream != null) respStream.Close();
??????????? if (resp != null) resp.Close();
??????????? request = null;
??????????? return bytData;
??????? }
??????? 數(shù)據(jù)獲取后，進(jìn)行必要的XML解析，以提取天氣數(shù)據(jù)。
??????? private void parseRssPage(byte[] rssPage)
??????? {
??????????? MemoryStream mStream = new MemoryStream(rssPage);
??????????? XmlReader xReader = XmlReader.Create(mStream);
??????????? forcastArray = new ArrayList();
??????????? while (xReader.Read())
??????????? {
??????????????? if (xReader.NodeType == XmlNodeType.Element)
??????????????? {
??????????????????? switch (xReader.Name)
??????????????????? {
?????????????????? ?????case "title":
??????????????????????????? xReader.Read();
??????????????????????????? break;
??????????????????????? case "pubDate":
??????????????????????????? xReader.Read();
??????????????????????????? break;
??????????????????????? case "yweather:location":
??????????????????????????? myCity = new cityInfo(xReader.GetAttribute("city"), xReader.GetAttribute("region"), xReader.GetAttribute("country"));
??????????????????????????? break;
??????????????????????? case "yweather:condition":
??????????????????????????? today = new todayCondition(xReader.GetAttribute("text"), xReader.GetAttribute("temp"), xReader.GetAttribute("date"));
???????????????????????????? break;
??????????????????????? case "yweather:forecast":
??????????????????????? ????forcastArray.Add(new forcastCondition(xReader.GetAttribute("day"), xReader.GetAttribute("date"), xReader.GetAttribute("low"),
??????????????????????????????? xReader.GetAttribute("high"), xReader.GetAttribute("text")));
???????????????????????????? break;
??????????????????? }
??????????????? }
??????????????? else if (xReader.NodeType == XmlNodeType.CDATA)
??????????????????? parseCDATA(xReader.Value);
??????????? }
??????? }
??????? 數(shù)據(jù)解析完畢后，就進(jìn)行屏幕顯示了。
??????????? public override void OnRender(DrawingContext dc)
??????????? {
??????????????? dc.DrawRectangle(new SolidColorBrush(Colors.White), new Pen(Colors.White), 0, 0, Width, Height);
??????????????? dc.DrawLine(new Pen(Colors.Gray), 10, 46, 310, 46);?????????????? dc.DrawImage(Resources.GetBitmap(Resources.BitmapResources.yahoo_news_wea), 10, 10);
??????????????? if (Program.weather != null)
??????????????? {
??????????????????? int Y = 60;
??????????????????? if (weather.MyCity != null) dc.DrawText(weather.MyCity.ToString(), Resources.GetFont(Resources.FontResources.small), Colors.Black, 10, Y);
??????????????????? if (weather.Today != null)
??????????????????? {
??????????????????????? dc.DrawText(weather.Today.date, Resources.GetFont(Resources.FontResources.small), Colors.Black, 10, Y + 20);
??????????????????????? dc.DrawText(weather.Today.weahterDesc + "?? temperature: " + weather.Today.curTemp + "c", Resources.GetFont(Resources.FontResources.small), Colors.Black, 10, Y + 40);
??????????????????? }
??????????????????? dc.DrawText("Forcast -- this week:", Resources.GetFont(Resources.FontResources.small), Colors.Black, 10, Y + 80);
??????????????????? Y += 80;
??????????????????? if (weather.ForcastArray != null)
??????????????????? {
??????????????????????? foreach (yahooWeatherRequest.forcastCondition forcast in weather.ForcastArray)
??????????????????????? {
??????????????????????????? string info = forcast.date + " , " + forcast.day + " , " + forcast.weahterDesc + " , " + forcast.lowTemp + "c ~ " + forcast.highTemp + "c ";
??????????????????????????? Y += 20;
??????????????????????????? dc.DrawText(info, Resources.GetFont(Resources.FontResources.small), Colors.Black, 10, Y);
??????????????????????? }
??????????????????? }
??????????????? }
????? 保證開發(fā)板正確的接入互聯(lián)網(wǎng)，注意設(shè)置好DNS服務(wù)器（這個(gè)事例也可以不用設(shè)置，不過如果測試官方的HttpClient事例，是一定要設(shè)置的，因?yàn)槟壳癕F的LWIP協(xié)議棧不支持默認(rèn)的DNS），運(yùn)行程序，則在超級終端中，我們可以看到我們從互聯(lián)網(wǎng)上請求的數(shù)據(jù)（如下圖）：
???? ?????
?????開發(fā)板運(yùn)行后的畫面如下：
????? ?
???? 開發(fā)板最新的固件版本：V0.9.06? 下載地址：http://www.sky-walker.com.cn/MFRelease/firmware/mfv41_firmware_hy_redbull.rar
?----------------------------------------------------------------------------------------------
源碼/文檔：http://www.sky-walker.com.cn/MFRelease/Sample/YFHttpClient.rar
MF快速入門：http://blog.csdn.net/yefanqiu/article/details/5340560
MF論壇：http://space.cnblogs.com/group/MFSoft/
MF開發(fā)板：http://item.taobao.com/item.htm?id=7117999726
網(wǎng)絡(luò)開發(fā)板：http://item.taobao.com/item.htm?id=10919470266
QQ群：127465602（已滿） 146524112
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