silverlight: http请求的GET及POST示例

http请求的get/post并不是难事，只是silverlight中一切皆是异步，所以代码看起来就显得有些冗长了，下面这个HttpHelper是在总结 园友 的基础上，修改得来：

namespace SLAwb.Helper
{
    public sealed class MediaType
    {
        /// <summary>
        /// "application/xml"
        /// </summary>
        public const string APPLICATION_XML = "application/xml";

        /// <summary>
        /// application/json
        /// </summary>
        public const string APPLICATION_JSON = "application/json";

        /// <summary>
        /// "application/x-www-form-urlencoded"
        /// </summary>
        public const string APPLICATION_FORM_URLENCODED = "application/x-www-form-urlencoded";
     
    }
}

using System;
using System.IO;
using System.Net;
using System.Threading;

namespace SLAwb.Helper
{
    /// <summary>
    /// Http工具类，用于向指定url发起Get或Post请求
    /// http://yjmyzz.cnblogs.com/
    /// </summary>
    public class HttpHelper
    {
        private string postData;
        SynchronizationContext currentContext;
        SendOrPostCallback sendOrPostCallback;

        /// <summary>
        /// 从指定url以Get方式获取数据
        /// </summary>
        /// <param name="url"></param>
        /// <param name="completedHandler"></param>
        public void Get(string url, DownloadStringCompletedEventHandler completedHandler)
        {
            WebClient client = new WebClient();
            client.DownloadStringCompleted += completedHandler;
            client.DownloadStringAsync(new Uri(url));
        }



        /// <summary>
        /// 向指定url地址Post数据
        /// </summary>
        /// <param name="url"></param>
        /// <param name="data"></param>
        /// <param name="mediaType"></param>
        /// <param name="synchronizationContext"></param>
        /// <param name="callBack"></param>
        public void Post(string url, string data, string mediaType, SynchronizationContext synchronizationContext, SendOrPostCallback callBack)
        {
            currentContext = synchronizationContext;
            Uri endpoint = new Uri(url);
            sendOrPostCallback = callBack;
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(endpoint);
            request.Method = "POST";
            request.ContentType = mediaType;
            postData = data;
            request.BeginGetRequestStream(new AsyncCallback(RequestReadySocket), request);
        }

        private void RequestReadySocket(IAsyncResult asyncResult)
        {
            WebRequest request = asyncResult.AsyncState as WebRequest;
            Stream requestStream = request.EndGetRequestStream(asyncResult);

            using (StreamWriter writer = new StreamWriter(requestStream))
            {
                writer.Write(postData);
                writer.Flush();
            }

            request.BeginGetResponse(new AsyncCallback(ResponseReadySocket), request);
        }

        private void ResponseReadySocket(IAsyncResult asyncResult)
        {
            try
            {
                WebRequest request = asyncResult.AsyncState as WebRequest;
                WebResponse response = request.EndGetResponse(asyncResult);
                using (Stream responseStream = response.GetResponseStream())
                {
                    StreamReader reader = new StreamReader(responseStream);
                    string paramStr = reader.ReadToEnd();
                    currentContext.Post(sendOrPostCallback, paramStr);
                }
            }
            catch (Exception e)
            {
                currentContext.Post(sendOrPostCallback, e.Message); 
            }
            
        }


    }
}

Silverlight中的测试代码：
xaml部分

<UserControl x:Class="SLAwb.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="480" d:DesignWidth="640">

    <Grid x:Name="LayoutRoot" Background="White">
        <Grid.RowDefinitions>
            <RowDefinition Height="30"></RowDefinition>
            <RowDefinition Height="*"></RowDefinition>
            <RowDefinition Height="2*"></RowDefinition>
        </Grid.RowDefinitions>        
        <Grid Grid.Row="0" Margin="3">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="40"></ColumnDefinition>
                <ColumnDefinition Width="*"></ColumnDefinition>
                <ColumnDefinition Width="75"></ColumnDefinition>
                <ColumnDefinition Width="95"></ColumnDefinition>
                <ColumnDefinition Width="80"></ColumnDefinition>
                <ColumnDefinition Width="80"></ColumnDefinition>
            </Grid.ColumnDefinitions>
            <TextBlock VerticalAlignment="Center" TextAlignment="Right">地址：</TextBlock>
            <TextBox Name="txtUrl" Grid.Column="1" Text="http://localhost/"></TextBox>
            <TextBlock Grid.Column="2" VerticalAlignment="Center" TextAlignment="Right">MediaType：</TextBlock>
            <TextBox Name="txtMediaType" Grid.Column="3" Text="application/xml"></TextBox>
            <Button Name="btnPost" Content="Post" Grid.Column="4" Margin="3,1" Click="btnPost_Click"></Button>
            <Button Name="btnGet" Content="Get" Grid.Column="5" Margin="3,1" Click="btnGet_Click"></Button>
        </Grid>
        
        <Grid Grid.Row="1">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="40"></ColumnDefinition>
                <ColumnDefinition Width="*"></ColumnDefinition>
            </Grid.ColumnDefinitions>
            <TextBlock VerticalAlignment="Top" TextAlignment="Right">数据：</TextBlock>
            <TextBox Name="txtPostData" Grid.Column="1" Margin="3" AcceptsReturn="True" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto"></TextBox>
        </Grid>

        <Grid Grid.Row="2">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="40"></ColumnDefinition>
                <ColumnDefinition Width="*"></ColumnDefinition>
            </Grid.ColumnDefinitions>
            <TextBlock VerticalAlignment="Top" TextAlignment="Right">返回：</TextBlock>
            <TextBox Name="txtResult" Grid.Column="1" Margin="3" AcceptsReturn="True" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto"></TextBox>
        </Grid>
    </Grid>
</UserControl>

cs部分

using SLAwb.Helper;
using System;
using System.Net;
using System.Threading;
using System.Windows;
using System.Windows.Controls;

namespace SLAwb
{
    public partial class MainPage : UserControl
    {
        private SynchronizationContext currentContext;


        public MainPage()
        {
            InitializeComponent();
            this.currentContext = SynchronizationContext.Current;
        }

        private void btnPost_Click(object sender, RoutedEventArgs e)
        {
            BeforeReturn();
            HttpHelper httpHelper = new HttpHelper();
            httpHelper.Post(txtUrl.Text, txtPostData.Text, txtMediaType.Text, currentContext, PostCompletedHandler);
        }

        private void PostCompletedHandler(Object obj)
        {
            txtResult.Text = obj.ToString();
        }

        private void btnGet_Click(object sender, RoutedEventArgs e)
        {
            BeforeReturn();
            HttpHelper httpHelper = new HttpHelper();
            httpHelper.Get(txtUrl.Text, GetCompletedHandler);            
        }


        void BeforeReturn() {
            txtResult.Text = "loading...";
        }


        void GetCompletedHandler(object sender, DownloadStringCompletedEventArgs e)
        {
            if (e.Error == null)
            {
                txtResult.Text = e.Result;
            }
            else
            {
                txtResult.Text = e.Error.Message;
            }
        }
    }
}