与众不同 windows phone (13) Background Task（后台任务）之后台文件传输（上传和下载）

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与众不同 windows phone (13) - Background Task（后台任务）之后台文件传输（上传和下载）

作者：webabcd


介绍
与众不同 windows phone 7.5 (sdk 7.1) 之后台任务

• 后台文件传输（下载）
• 后台文件传输（上传）

示例
1、演示如何实现后台文件传输（下载）
BackgroundTransferDownload.xaml

<phone:PhoneApplicationPage 
    x:Class="Demo.BackgroundTask.BackgroundTransferDownload"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="Portrait" Orientation="Portrait"
    mc:Ignorable="d" d:DesignHeight="768" d:DesignWidth="480"
    shell:SystemTray.IsVisible="True">

    <Grid x:Name="LayoutRoot" Background="Transparent">
        <StackPanel Orientation="Vertical">
            
            <Button x:Name="btnDownloadSilverlightDemo" Content="下载 Silverlight Demo 压缩包" Click="btnDownloadSilverlightDemo_Click" />
            <Button x:Name="btnDownloadXNADemo" Content="下载 XNA Demo 压缩包" Click="btnDownloadXNADemo_Click" />
            <Button x:Name="btnDownloadWindowsPhoneDemo" Content="下载 WindowsPhone Demo 压缩包" Click="btnDownloadWindowsPhoneDemo_Click" />

            <TextBlock Text="下载任务列表：" Margin="0 15 0 0" />
            <ListBox Name="listBox">
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <Grid Margin="0 15" Width="480">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="8*"/>
                                <ColumnDefinition Width="2*"/>
                            </Grid.ColumnDefinitions>
                            
                            <Grid>
                                <StackPanel Orientation="Vertical">
                                    <StackPanel Orientation="Horizontal">
                                        <TextBlock Text="文件名: "/>
                                        <TextBlock Text="{Binding Tag}"/>
                                    </StackPanel>
                                    <StackPanel Orientation="Horizontal">
                                        <TextBlock Text="下载状态: "/>
                                        <TextBlock Text="{Binding TransferStatus}" />
                                    </StackPanel>
                                    <StackPanel Orientation="Horizontal">
                                        <TextBlock Text="已接收字节数: "/>
                                        <TextBlock Text="{Binding BytesReceived}" />
                                    </StackPanel>
                                    <StackPanel Orientation="Horizontal">
                                        <TextBlock Text="总共字节数: "/>
                                        <TextBlock Text="{Binding TotalBytesToReceive}" />
                                    </StackPanel>
                                </StackPanel>

                            </Grid>
                            <Grid Grid.Column="1">
                                <Button x:Name="btnCancel" Tag="{Binding RequestId}" Click="btnCancel_Click" Content="删除任务"></Button>
                            </Grid>
                        </Grid>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>
            
        </StackPanel>        
    </Grid>
 
</phone:PhoneApplicationPage>

BackgroundTransferDownload.xaml.cs

/*
 * 演示如何实现后台文件传输（下载）
 * 
 * 
 * BackgroundTransferRequest - 后台文件传输请求
 *     BackgroundTransferRequest(Uri) - 构造函数。参数解释：下载时其为需要下载的文件的远程地址；上传时其为接收文件的远程服务地址
 *     RequestId - 后台文件传输请求的唯一 ID，只读
 *     RequestUri - 请求的地址，只读。其需要在构造函数中设置
 *     Method - 请求的 http 方法，GET - 下载；POST - 上传
 *     Headers - 请求的 http 头，有一些头信息不能自定义，如 Range 等
 *     StatusCode - http 请求回应的状态码
 *     Tag - 自定义此对象的关联信息，即上下文数据
 *     TransferPreferences - 传输的启动条件（Microsoft.Phone.BackgroundTransfer.TransferPreferences 枚举）
 *         None - 仅在外部电源 + WiFi 环境下允许传输
 *         AllowCellular - 允许在手机网络环境下传输
 *         AllowBattery - 允许在电池做电源的环境下传输
 *         AllowCellularAndBattery - 允许在电池电源 + 手机网络的环境下传输
 *     TransferError - 错误信息
 *     TransferStatus - 传输状态（Microsoft.Phone.BackgroundTransfer.TransferStatus 枚举）
 *         None - 传输任务尚未加入到传输队列
 *         Waiting - 在传输队列，等待传输
 *         Transferring - 传输中
 *         Paused - 暂停
 *         Completed - 传输任务已完成，如果传输成功则 TransferError 为 null
 *         WaitingForWiFi - WiFi 网络
 *         WaitingForExternalPower - 需要接上外接电源
 *         WaitingForExternalPowerDueToBatterySaverMode - 需要接上外接电源，或者禁用节电模式
 *         WaitingForNonVoiceBlockingNetwork - 不能使用无法和语音并发的网络（如 2G、EDGE 和标准 GPRS）
 *     DownloadLocation - 下载到的目标位置
 *     UploadLocation - 需要上传的文件的地址
 *     BytesReceived - 文件已下载的字节数
 *     BytesSent - 文件已上传的字节数
 *     TotalBytesToReceive - 需要下载的文件的总字节数（-1 则文件大小未知）
 *     TotalBytesToSend - 需要上传的文件的总字节数（-1 则文件大小未知）
 *     
 *     TransferProgressChanged - 传输进度改变时所触发的事件
 *     TransferStatusChanged - 属性 TransferStatus 发生改变时所触发的事件
 * 
 * 
 * BackgroundTransferService - 对后台文件传输请求的管理
 *     Add() - 添加一个 BackgroundTransferRequest
 *     Find() - 通过 RequestId 查找指定的 BackgroundTransferRequest
 *     Remove - 通过 RequestId 删除指定的 BackgroundTransferRequest
 *     
 * 
 * 注意：
 * 后台文件传输既支持 http 又支持 https
 * 传输的文件必须在 /shared/transfers 目录下
 * 上传文件最大 5 MB，手机网络下载文件最大 20 MB，WiFi+电池电源下载文件最大 100 MB，WiFi+外接电源下载文件则允许大于 100 MB
 * 下载文件超过 5 MB 时，系统会向服务端发 Range 头分段下载（不会多线程下载，但是会断点续传）
 * 每个应用程序的传输任务队列，最大支持 5 个任务，设备支持 500 个任务
 * 设备上最大并发传输数为 2 个
 */

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 Microsoft.Phone.Controls;

using Microsoft.Phone.BackgroundTransfer;
using System.IO.IsolatedStorage;

namespace Demo.BackgroundTask
{
    public partial class BackgroundTransferDownload : PhoneApplicationPage
    {
        public BackgroundTransferDownload()
        {
            InitializeComponent();
        }

        protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
        {
            // 为每个 BackgroundTransferRequest 注册相关事件
            foreach (var transfer in BackgroundTransferService.Requests)
            {
                transfer.TransferStatusChanged += new EventHandler<BackgroundTransferEventArgs>(transfer_TransferStatusChanged);
                transfer.TransferProgressChanged += new EventHandler<BackgroundTransferEventArgs>(transfer_TransferProgressChanged);
            }

            UpdateUI(); 
        }

        private void ProcessTransfer(BackgroundTransferRequest transfer)
        {
            switch (transfer.TransferStatus)
            {
                case TransferStatus.Completed:
                    // 200 - 下载完成；206 - 分块下载完成
                    if (transfer.StatusCode == 200 || transfer.StatusCode == 206)
                    {
                        // 下载完成后不会自动从队列中删除，需要手动删除
                        RemoveTransferRequest(transfer.RequestId);

                        // 将下载完成后的文件移动到独立存储的根目录下
                        using (IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication())
                        {
                            string filename = transfer.Tag;
                            if (isoStore.FileExists(filename))
                            {
                                isoStore.DeleteFile(filename);
                            }
                            isoStore.MoveFile(transfer.DownloadLocation.OriginalString, filename);
                        }
                    }
                    else
                    {
                        // 如果回应的不是 200 或 206 则意味着出现了问题
                        // 将任务其移出队列
                        RemoveTransferRequest(transfer.RequestId);

                        // 发生了异常，做一些相关处理
                        if (transfer.TransferError != null)
                        {
                            MessageBox.Show(transfer.TransferError.ToString());
                        }
                    }
                    break;

                // 注：以下 4 个状态最好做一下判断和处理，然后呈现给用户
                case TransferStatus.WaitingForExternalPower:
                    break;
                case TransferStatus.WaitingForExternalPowerDueToBatterySaverMode:
                    break;
                case TransferStatus.WaitingForNonVoiceBlockingNetwork:
                    break;
                case TransferStatus.WaitingForWiFi:
                    break;
            }
        }

        void transfer_TransferStatusChanged(object sender, BackgroundTransferEventArgs e)
        {
            ProcessTransfer(e.Request);

            UpdateUI();
        }

        void transfer_TransferProgressChanged(object sender, BackgroundTransferEventArgs e)
        {
            UpdateUI();
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            string transferId = ((Button)sender).Tag as string;
            RemoveTransferRequest(transferId);

            UpdateUI();
        }

        // 从 BackgroundTransferService 中删除指定的传输请求
        private void RemoveTransferRequest(string transferId)
        {
            BackgroundTransferRequest transfer = BackgroundTransferService.Find(transferId);

            try
            {
                if (transfer != null)
                    BackgroundTransferService.Remove(transfer);
            }
            catch (Exception ex)
            {
                MessageBox.Show("RemoveTransferRequest: " + ex.ToString());
            }
        }

        private void UpdateUI()
        {
            // 更新 UI
            listBox.ItemsSource = BackgroundTransferService.Requests;
        }

        private void btnDownloadSilverlightDemo_Click(object sender, RoutedEventArgs e)
        {
            // 如果 url 中有特殊字符，如汉字等，建议使用 Uri.EscapeUriString 编码
            AddBackgroundTransfer("Silverlight.rar", new Uri("https://files.cnblogs.com/webabcd/Silverlight.rar", UriKind.Absolute));

            UpdateUI();
        }

        private void btnDownloadXNADemo_Click(object sender, RoutedEventArgs e)
        {
            AddBackgroundTransfer("XNA.rar", new Uri("https://files.cnblogs.com/webabcd/XNA.rar", UriKind.Absolute));

            UpdateUI();
        }

        private void btnDownloadWindowsPhoneDemo_Click(object sender, RoutedEventArgs e)
        {
            AddBackgroundTransfer("WindowsPhone.rar", new Uri("https://files.cnblogs.com/webabcd/WindowsPhone.rar", UriKind.Absolute));

            UpdateUI();
        }

        /// <summary>
        /// 添加后台传输任务到队列
        /// </summary>
        /// <param name="fileName">需要在本地保存的文件名</param>
        /// <param name="fileUri">需要下载的文件的远程地址</param>
        private void AddBackgroundTransfer(string fileName, Uri fileUri)
        {
            // 做一下相关判断
            if (BackgroundTransferService.Requests.Count() >= 5)
            {
                MessageBox.Show("每个应用程序的后台传输队列最多只能有 5 个任务");
                return;
            }
            if (BackgroundTransferService.Requests.Any(p => p.RequestUri == fileUri))
            {
                MessageBox.Show("任务已在队列中");
                return;
            }

            BackgroundTransferRequest transferRequest = new BackgroundTransferRequest(fileUri);
            transferRequest.Method = "GET"; // 下载
            transferRequest.TransferPreferences = TransferPreferences.None; // 仅在外部电源 + WiFi 环境下允许下载

            transferRequest.TransferStatusChanged += new EventHandler<BackgroundTransferEventArgs>(transfer_TransferStatusChanged);
            transferRequest.TransferProgressChanged += new EventHandler<BackgroundTransferEventArgs>(transfer_TransferProgressChanged);

            transferRequest.Tag = fileName; // 给 TransferRequest 赋值一个上下文数据
            transferRequest.DownloadLocation = new Uri("shared/transfers/" + fileName, UriKind.Relative);

            try
            {
                BackgroundTransferService.Add(transferRequest);
            }
            catch (Exception ex)
            {
                MessageBox.Show("AddBackgroundTransfer: " + ex.ToString());
            }
        }
    }
}

2、演示如何实现后台文件传输（上传）
BackgroundTransferUpload.xaml

<phone:PhoneApplicationPage 
    x:Class="Demo.BackgroundTask.BackgroundTransferUpload"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="Portrait" Orientation="Portrait"
    mc:Ignorable="d" d:DesignHeight="768" d:DesignWidth="480"
    shell:SystemTray.IsVisible="True">

    <Grid x:Name="LayoutRoot" Background="Transparent">
        <StackPanel Orientation="Vertical">

            <Button x:Name="btnUpload" Content="上传 Demo.mp4 文件到服务端" Click="btnUpload_Click" />

        </StackPanel>
    </Grid>
 
</phone:PhoneApplicationPage>

BackgroundTransferUpload.xaml.cs

/*
 * 演示如何实现后台文件传输（上传）
 * 
 * BackgroundTransferRequest、BackgroundTransferService 及相关注意事项详见：BackgroundTask/BackgroundTransferDownload.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 Microsoft.Phone.Controls;

using Microsoft.Phone.BackgroundTransfer;
using System.IO.IsolatedStorage;
using System.Windows.Resources;
using System.IO;

namespace Demo.BackgroundTask
{
    public partial class BackgroundTransferUpload : PhoneApplicationPage
    {
        public BackgroundTransferUpload()
        {
            InitializeComponent();
        }

        protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
        {
            // 为每个 BackgroundTransferRequest 注册相关事件
            foreach (var transfer in BackgroundTransferService.Requests)
            {
                transfer.TransferStatusChanged += new EventHandler<BackgroundTransferEventArgs>(transfer_TransferStatusChanged);
                transfer.TransferProgressChanged += new EventHandler<BackgroundTransferEventArgs>(transfer_TransferProgressChanged);
            }
        }

        private void ProcessTransfer(BackgroundTransferRequest transfer)
        {
            switch (transfer.TransferStatus)
            {
                case TransferStatus.Completed:
                    // 200 代表上传成功
                    if (transfer.StatusCode == 200)
                    {
                        MessageBox.Show("上传成功");
                    }
                    else
                    {
                        // 发生了异常，做一些相关处理
                        if (transfer.TransferError != null)
                        {
                            MessageBox.Show(transfer.TransferError.ToString());
                        }
                    }
                    RemoveTransferRequest(transfer.RequestId);
                    break;

                // 注：以下 4 个状态最好做一下判断和处理，然后呈现给用户
                case TransferStatus.WaitingForExternalPower:
                    break;
                case TransferStatus.WaitingForExternalPowerDueToBatterySaverMode:
                    break;
                case TransferStatus.WaitingForNonVoiceBlockingNetwork:
                    break;
                case TransferStatus.WaitingForWiFi:
                    break;
            }
        }

        void transfer_TransferStatusChanged(object sender, BackgroundTransferEventArgs e)
        {
            ProcessTransfer(e.Request);
        }

        void transfer_TransferProgressChanged(object sender, BackgroundTransferEventArgs e)
        {
            // 上传进度发生改变
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            string transferId = ((Button)sender).Tag as string;
            RemoveTransferRequest(transferId);
        }

        // 从 BackgroundTransferService 中删除指定的传输请求
        private void RemoveTransferRequest(string transferId)
        {
            BackgroundTransferRequest transfer = BackgroundTransferService.Find(transferId);

            try
            {
                if (transfer != null)
                    BackgroundTransferService.Remove(transfer);
            }
            catch (Exception ex)
            {
                MessageBox.Show("RemoveTransferRequest: " + ex.ToString());
            }
        }

        private void btnUpload_Click(object sender, RoutedEventArgs e)
        {
            // 将 Demo.mp4 文件从程序包复制到独立存储的 shared/transfers 目录，以备上传
            StreamResourceInfo sr = Application.GetResourceStream(new Uri("Assets/Demo.mp4", UriKind.Relative));
            using (BinaryReader br = new BinaryReader(sr.Stream))
            {
                byte[] data = br.ReadBytes((int)sr.Stream.Length);

                IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication();
                using (var isfs = new IsolatedStorageFileStream(@"shared/transfers/Demo.mp4", FileMode.Create, isf))
                {
                    using (var bw = new BinaryWriter(isfs))
                    {
                        bw.Write(data);
                    }
                }
            }

            AddBackgroundTransfer("Demo.mp4", new Uri(@"shared/transfers/Demo.mp4", UriKind.Relative));
        }

        /// <summary>
        /// 添加后台传输任务到队列
        /// </summary>
        /// <param name="fileName">需要在服务端保存的文件名</param>
        /// <param name="fileUri">需要上传的文件的本地地址</param>
        private void AddBackgroundTransfer(string fileName, Uri fileUri)
        {
            BackgroundTransferRequest transferRequest = new BackgroundTransferRequest(new Uri("http://localhost:15482/UploadFile.aspx?fileName=" + fileName, UriKind.Absolute));
            transferRequest.Method = "POST"; // 上传
            transferRequest.TransferPreferences = TransferPreferences.None; // 仅在外部电源 + WiFi 环境下允许上传

            transferRequest.TransferStatusChanged += new EventHandler<BackgroundTransferEventArgs>(transfer_TransferStatusChanged);
            transferRequest.TransferProgressChanged += new EventHandler<BackgroundTransferEventArgs>(transfer_TransferProgressChanged);

            transferRequest.UploadLocation = fileUri;

            try
            {
                BackgroundTransferService.Add(transferRequest);
            }
            catch (Exception ex)
            {
                MessageBox.Show("AddBackgroundTransfer: " + ex.ToString());
            }
        }
    }
}

UploadFile.aspx.cs（用于保存上传文件的服务端代码）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;

namespace Web
{
    public partial class UploadFile : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (Request.TotalBytes > 0)
            {
                // 保存上传过来的文件
                byte[] data = Request.BinaryRead(Request.TotalBytes);
                File.WriteAllBytes(@"C:\" + Request.QueryString["fileName"], data);
            }
        }
    }
}

OK
[源码下载]