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稳扎稳打Silverlight(21) - 2.0通信之WebRequest和WebResponse,对指定的URI发出请求以及接收响应
作者：webabcd
介绍
Silverlight 2.0 详解WebRequest和WebResponse，对指定的URI做GET和POST请求，以及接收其响应
HttpWebRequest - 对指定的 URI 发出请求
Create() - 初始化一个 WebRequest
BeginGetResponse() - 开始对指定 URI 资源做异步请求
EndGetResponse() - 结束对指定 URI 资源做异步请求
HttpWebResponse - 对指定的 URI 做出响应
GetResponseStream() - 获取响应的数据流
在线DEMO
http://www.voidcn.com/article/p-ounmxjds-tq.html
示例
1、对指定的URI做GET请求以及接收响应
WebRequestGet.xaml
<UserControl x:Class="Silverlight20.Communication.WebRequestGet"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<StackPanel HorizontalAlignment="Left" Margin="5">
<TextBlock x:Name="lblMsg" />
</StackPanel>
</UserControl>
WebRequestGet.xaml.cs
using Sy
stem;
using Sy
stem.Collections.Generic;
using Sy
stem.Linq;
using Sy
stem.Net;
using Sy
stem.Windows;
using Sy
stem.Windows.Controls;
using Sy
stem.Windows.Documents;
using Sy
stem.Windows.Input;
using Sy
stem.Windows.Media;
using Sy
stem.Windows.Media.Animation;
using Sy
stem.Windows.Shapes;
using Sy
stem.Threading;
using Sy
stem.IO;
namespace Silverlight20.Communication
{
public partial
class WebRequestGet : UserControl
{
// 接收 GET 方式数据的 REST 服务
string _url =
"http://localhost:3036/REST.svc/Users/json";
// 异常信息
string _exception = "";
// SynchronizationContext - 同步上下文管理类
SynchronizationContext _syncContext;
public WebRequestGet()
{
InitializeComponent();
Demo();
}
void Demo()
{
// SynchronizationContext.Current - 当前线程的同步上下文
_syncContext = SynchronizationContext.Current;
/*
* HttpWebRequest - 对指定的 URI 发出请求
* HttpWebRequest.Create(uri) - 初始化一个 WebRequest
* HttpWebRequest.BeginGetResponse(AsyncCallback callback,Object state) - 开始对指定 URI 资源做异步请求
* AsyncCallback callback - System.AsyncCallback 委托。异步操作完成时调用的回调方法
* Object state - 包含此异步请求的对象。即相应的 HttpWebRequest 对象
* HttpWebRequest.Abort() - 取消该异步请求
* HttpWebRequest.Accept - HTTP 头的 Accept 部分
* HttpWebRequest.ContentType - HTTP 头的 ContentType 部分
* HttpWebRequest.Headers - HTTP 头的 key/value 对集合
* HttpWebRequest.Method - HTTP 方法（只支持GET和POST）
* HttpWebRequest.RequestUri - 所请求的 URI
* HttpWebRequest.HaveResponse - 是否接收到了指定 URI 的响应
* HttpWebRequest.AllowReadStreamBuffering - 是否对从 Internet 资源接收的数据做缓冲处理。默认值为true，将数据缓存在客户端内存中，以便随时被应用程序读取
*/
HttpWebRequest request = WebRequest.Create(
new Uri(_url,UriKind.Absolute)) as HttpWebRequest;
request.Method = "GET";
request.BeginGetResponse(new AsyncCallback(ResponseCallback),request);
}
private void ResponseCallback(IAsyncResult result)
{
// IAsyncResult.AsyncState - AsyncCallback 传过来的对象
HttpWebRequest request = result.AsyncState as HttpWebRequest;
WebResponse response = null;
try
{
// HttpWebRequest.EndGetResponse(IAsyncResult) - 结束对指定 URI 资源做异步请求
// 返回值为 WebResponse 对象
response = request.EndGetResponse(result) as HttpWebResponse;
}
catch (Exception ex)
{
_exception = ex.ToString();
}
// SynchronizationContext.Post(SendOrPostCallback d,Object state) - 将异步消息发送到该同步上下文中
// SendOrPostCallback d - System.Threading.SendOrPostCallback 委托
// Object state - 需要传递的参数
_syncContext.Post(GetResponse,response);
}
private void GetResponse(object state)
{
/*
* HttpWebResponse - 对指定的 URI 做出响应
* GetResponseStream() - 获取响应的数据流
*/
HttpWebResponse response = state as HttpWebResponse;
if (response != null)
{
Stream responseStream = response.GetResponseStream();
using (StreamReader sr = new StreamReader(responseStream))
{
lblMsg.Text = sr.ReadToEnd();
}
}
else
{
lblMsg.Text = _exception;
}
}
}
}
2、对指定的URI做POST请求以及接收响应
WebRequestPost.xaml
<UserControl x:Class="Silverlight20.Communication.WebRequestPost"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<StackPanel HorizontalAlignment="Left" Margin="5">
<TextBlock x:Name="lblMsg" />
</StackPanel>
</UserControl>
WebRequestPost.xaml.cs
using Sy
stem;
using Sy
stem.Collections.Generic;
using Sy
stem.Linq;
using Sy
stem.Net;
using Sy
stem.Windows;
using Sy
stem.Windows.Controls;
using Sy
stem.Windows.Documents;
using Sy
stem.Windows.Input;
using Sy
stem.Windows.Media;
using Sy
stem.Windows.Media.Animation;
using Sy
stem.Windows.Shapes;
using Sy
stem.Threading;
using Sy
stem.IO;
namespace Silverlight20.Communication
{
public partial
class WebRequestPost : UserControl
{
// 接收 POST 方式数据的 REST 服务
string _url =
"http://localhost:3036/REST.svc/PostUser";
// 异常信息
string _exception = "";
// SynchronizationContext - 同步上下文管理类
SynchronizationContext _syncContext;
public WebRequestPost()
{
InitializeComponent();
Demo();
}
void Demo()
{
_syncContext = SynchronizationContext.Current;
HttpWebRequest request = WebRequest.Create(
new Uri(_url,UriKind.Absolute)) as HttpWebRequest;
request.Method = "POST";
// BeginGetRequestStream(AsyncCallback callback,Object state) - 向指定的 URI 资源发送数据的流的异步请求
// AsyncCallback callback - System.AsyncCallback 委托
// Object state - 包含此异步请求的对象。即相应的 HttpWebRequest 对象
IAsyncResult asyncResult = request.BeginGetRequestStream(
new AsyncCallback(RequestStreamCallback),request);
}
private void RequestStreamCallback(IAsyncResult result)
{
HttpWebRequest request = result.AsyncState as HttpWebRequest;
request.ContentType = "application/x-www-form-urlencoded";
// HttpWebRequest.EndGetRequestStream(IAsyncResult) - 返回用于将数据写入某 URI 资源的 Stream
Stream requestStream = request.EndGetRequestStream(result);
StreamWriter streamWriter = new StreamWriter(requestStream);
// byte[] postdata = System.Text.Encoding.UTF8.GetBytes("name=webabcd");
// 多个参数用“&”分隔
streamWriter.Write("name=webabcd");
streamWriter.Close();
request.BeginGetResponse(new AsyncCallback(ResponseCallback),request);
}
private void ResponseCallback(IAsyncResult result)
{
HttpWebRequest request = result.AsyncState as HttpWebRequest;
WebResponse response = null;
try
{
response = request.EndGetResponse(result);
}
catch (Exception ex)
{
_exception = ex.ToString();
}
// 调用 UI 线程
_syncContext.Post(GetResponse,response);
}
private void GetResponse(object state)
{
/*
* HttpWebResponse - 对指定的 URI 做出响应
* GetResponseStream() - 获取响应的数据流
* ContentLength - 接收的数据的内容长度
* ContentType - HTTP 头的 ContentType 部分
* Method - HTTP 方法
* ResponseUri - 响应该请求的 URI
* StatusCode - 响应状态 [System.Net.HttpStatusCode枚举]
* HttpStatusCode.OK - HTTP 状态为 200
* HttpStatusCode.NotFound - HTTP 状态为 404
* StatusDescription - 响应状态的说明
*/
HttpWebResponse response = state as HttpWebResponse;
if (response != null && response.StatusCode == HttpStatusCode.OK)
{
Stream responseStream = response.GetResponseStream();
using (StreamReader sr = new StreamReader(responseStream))
{
lblMsg.Text = string.Format("接收的数据的内容长度：{0}\r\nHTTP 头的 ContentType 部分：{1}\r\nHTTP 方法：{2}\r\n响应该请求的 URI：{3}\r\n响应状态：{4}\r\n响应状态的说明：{5}\r\n响应的结果：{6}\r\n",
response.ContentLength,
response.ContentType,
response.Method,
response.ResponseUri,
response.StatusCode,
response.StatusDescription,
sr.ReadToEnd());
}
}
else
{
lblMsg.Text = _exception;
}
}
}
}
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