Windows phone开发 网络编程之HttpWebRequest

来源:转载

HttpWebRequest和WebClient的区别
1,HttpWebRequest是个抽象类,所以无法new的,需要调用HttpWebRequest.Create();
2,其Method指定了请求类型,这里用的GET,还有POST;也可以指定ConentType;
3,其请求的Uri必须是绝对地址;
4,其请求是异步回调方式的,从BeginGetResponse开始,并通过AsyncCallback指定回调方法;
5,WebClient方式使用基于事件的异步编程模型,在HTTP响应返回时引发的WebClient回调是在UI线程中调用的,因此可用于更新UI元素的性。HttpWebRequest是基于后台进程运行的,回调不是UI线程,所以不能直接对UI进行操作,通常使用Dispatcher.BeginInvoke()跟界面进行通讯。


HTTP中GET请求与POST请求的区别:
1.GET请求是从服务器上获取数据                           POST请求是向服务器传送数据
2.GET请求在通过URL提交数据,数据在URL中可以看到         POST请求数据是通过写入数据流的方式提交
3.GET请求提交的数据最多只能1024个字节                   POST请求提交的数据没有限制

 

HttpWebRequest类实现GET请求

1.通过HttpWebRequest.CreateHttp()方法可以创建一个HttpWebRequest对象;

2.设置请求的参数(如设置请求方式为GET);

3.发起异步响应请求:BeginGetGetResponse;

4.结束异步响应EndGetResponse;

5.获取请求的内容;

6.对请求进行异常处理。

通过下面的例子增加对HttpWebRequest类的GET请求方式的理解:

 1 public void httpWebRequestGet() 2 { 3 try{ 4 String uri = "http://www.baidu.com/ "; 5 WebRequest request = HttpWebRequest.CreateHttp(new Uri(uri)); //创建WebRequest对象 6 request.Method = "GET"; //设置请求方式为GET 7 request.BeginGetResponse(responseStreamCallback, request); //发起GetResponse请求,返回应答请求异步操作的状态 8 } 9 catch(WebException e)10 {11 outputBlock.Text += "/n出现异常请求失败!/n";12 outputBlock.Text += "异常信息: ";13 outputBlock.Text += e.Message;14 outputBlock.Text += "/nStatus: ";15 outputBlock.Text += e.Status;16 }17 catch(Exception e)18 {19 outputBlock.Text += "/n出现异常请求失败!/n";20 outputBlock.Text += "/n异常信息: ";21 outputBlock.Text += e.Message;22 }23 }24 25 private void responseCallback(IAsyncResult result)26 { 27 try{ 28 HttpWebRequest request = (HttpWebRequest)result.AsyncState; //获取异步操作返回的的信息 29 WebResponse response = request.EndGetResponse(result);30 using (Stream stream = response.GetResponseStream()) //获取请求返回内容31 using(StreamReader read = new StreamReader(stream)) 32 {33 string text = read.ReadToEnd();34 Dispatcher.BeginInvoke(() => //使用Dispatcher.BeginInvoke()更新UI信息35 {36 textBlock1.Text = text;37 });38 }39 40 }41 //异常处理42 catch(WebException e)43 {44 outputBlock.Text += "/n出现异常请求失败!/n";45 outputBlock.Text += "异常信息: ";46 outputBlock.Text += e.Message;47 outputBlock.Text += "/nStatus: ";48 outputBlock.Text += e.Status;49 }50 catch(Exception e)51 {52 outputBlock.Text += "/n出现异常请求失败!/n";53 outputBlock.Text += "/n异常信息: ";54 outputBlock.Text += e.Message;55 }56 }

 

HttpWebRequest类实现POST请求

1.通过HttpWebRequest.CreateHttp()方法可以创建一个HttpWebRequest对象;

2.设置请求的参数(如设置请求方式为POST)

3.发起获取要发送的数据流请求:BeginGetRequestStreamGetResponseStream请求;

4.结束异步的数据流请求:EndGetRequestStream;

5.把要传递的数据写入数据流;

6.发起异步响应请求:BeginGetGetResponse;

7.结束异步响应EndGetResponse ;

8.获取请求的内容;

9.对请求进行异常处理

通过下面的例子增加对HttpWebRequest类的POST请求方式的理解:

 1 public void httpWebRequestPost() 2 { 3 try{ 4 String uri = "http://www.baidu.com/ "; 5 WebRequest request = HttpWebRequest.CreateHttp(new Uri(uri)); //创建WebRequest对象 6 request.Method = "POST"; //设置请求方式为POST 7 request.BeginGetRequestStream(responseStreamCallback, request); //发起GetResponseStream请求,返回应答请求异步操作的状态 8 } 9 catch(WebException e)10 {11 outputBlock.Text += "/n出现异常请求失败!/n";12 outputBlock.Text += "异常信息: ";13 outputBlock.Text += e.Message;14 outputBlock.Text += "/nStatus: ";15 outputBlock.Text += e.Status;16 }17 catch(Exception e)18 {19 outputBlock.Text += "/n出现异常请求失败!/n";20 outputBlock.Text += "/n异常信息: ";21 outputBlock.Text += e.Message;22 }23 }24 //发起获取发送数据流的请求的响应25 26 peivate void responseStreamCallback(IAsyncResult result)27 {28 HttpWebRequest request = (HttpWebRequest)result.AsyncState; //获取异步操作返回的的信息 29 Stream stream = "hello world!";30 byte[] data = Encoding.UTF8.GetBytes(postString);31 stream.Write(data,0,data.Length);32 stream.Close();33 request.BeginGetResponse(responseCallback, request);34 }35 36 private void responseCallback(IAsyncResult result)37 { 38 try{ 39 HttpWebRequest request = (HttpWebRequest)result.AsyncState; //获取异步操作返回的的信息 40 WebResponse response = (WebResponse)request.EndGetResponse(result); 41 using (Stream stream = response.GetResponseStream()) 42 using ( StreamReader read = new StreamReader(stream)43 {44 string text = read.ReadToEnd();45 Dispatcher.BeginInvoke(() => //使用Dispatcher.BeginInvoke()更新UI信息46 {47 textBlock.Text = text;48 });49 }50 51 }52 //异常处理53 catch(WebException e)54 {55 outputBlock.Text += "/n出现异常请求失败!/n";56 outputBlock.Text += "异常信息: ";57 outputBlock.Text += e.Message;58 outputBlock.Text += "/nStatus: ";59 outputBlock.Text += e.Status;60 }61 catch(Exception e)62 {63 outputBlock.Text += "/n出现异常请求失败!/n";64 outputBlock.Text += "/n异常信息: ";65 outputBlock.Text += e.Message;66 }67 }

 

文章为作者原创,转载请标明出处,谢谢  http://www.cnblogs.com/spilledlight/p/4929418.html



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