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

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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://webabcd.blog.51cto.com/1787395/342779

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 System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using System.Threading;
using System.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 System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using System.Threading;
using System.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;
                        }
                }
        }
}

 

 

OK
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