Windows Phone网络HttpWebRequest用法

在Windows Phone系统中，通过HttpWebRequest类可以很容易的发送网络请求，获取网络数据。HttpWebRequest是异步操作，不会堵塞主线程。
　　1.通过HttpWebRequest.CreateHttp()方法可以创建一个HttpWebRequest，下面代码简单实现发送一个GET请求。
  httpGet
 
        public void httpGet()
        {
            try
            {
                //请求地址
                String url = "http://www.2cto.com/ ";
                //创建WebRequest类
                HttpWebRequest request = HttpWebRequest.CreateHttp(new Uri(url));

                //设置请求方式GET POST
                request.Method = "GET";

                //返回应答请求异步操作的状态
                request.BeginGetResponse(responseCallback, request);
            }
            catch (WebException e)
            {
                //网络相关异常处理
            }
            catch (Exception e)
            {
                //异常处理
            }
        }
 
　　2.应答数据接收部分。
  responseCallback
 
        private void responseCallback(IAsyncResult result)
        {
            try
            {
                //获取异步操作返回的的信息
                HttpWebRequest request = (HttpWebRequest)result.AsyncState;
                //结束对 Internet 资源的异步请求
                HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(result);
                //解析应答头
                //parseRecvHeader(response.Headers);
                //获取请求体信息长度
                long contentLength = response.ContentLength;

                //获取应答码
                int statusCode = (int)response.StatusCode;
                string statusText = response.StatusDescription;

                //应答头信息验证
                using (Stream stream = response.GetResponseStream())
                {
                    //获取请求信息
                    StreamReader read = new StreamReader(stream);
                    string msg = read.ReadToEnd();
                    Deployment.Current.Dispatcher.BeginInvoke(() =>
                    {
                        textBlock1.Text = msg;
                    });
                }

            }
            catch (WebException e)
            {
                //连接失败               
            }
            catch (Exception e)
            {
                //异常处理
               
            }

        }
 
　　通过HttpWebResponse可以获取返回的数据，在获取数据后，要想将数据显示到界面中，这里要主要一个问题。由于 HttpWebRequest是异步操作，所以这里应该有一个线程来处理网络，大家都知道Windows Phone中在线程里是不能操作UI的，这个需要交个UI主线程来处理，所以代码中用到了 Deployment.Current.Dispatcher.BeginInvoke。
　　3.上面是简单的GET请求，POST请求和GET请求相比，多了一个发送请求体的操作过程。以下代码为POST请求，应对部分操作函数仍然是responseCallback。
  httpPost
 
        public void httpPost()
        {
            try
            {
                //请求地址
                String url = "http://www.2cto.com/ ";
                //创建WebRequest类
                HttpWebRequest request = HttpWebRequest.CreateHttp(new Uri(url));

                //设置请求方式GET POST
                request.Method = "POST";

                //返回应答请求异步操作的状态
                request.BeginGetRequestStream(requestCallback, request);
            }
            catch (WebException e)
            {
                //网络相关异常处理
            }
            catch (Exception e)
            {
                //异常处理
            }
        }

        private void requestCallback(IAsyncResult result)
        {
            try
            {
                //获取异步操作返回的的信息
                HttpWebRequest request = (HttpWebRequest)result.AsyncState;
                //结束对 Internet 资源的异步请求
                StreamWriter postStream = new StreamWriter(request.EndGetRequestStream(result));
                postStream.WriteLine("作者：宇之乐");
                postStream.WriteLine("");

                //返回应答请求异步操作的状态
                request.BeginGetResponse(responseCallback, request);
            }
            catch (WebException e)
            {
                //异常处理

            }
            catch (Exception e)
            {
                //异常处理

            }
        }