DownloadBase     /// <summary>    /// 下载器基类    /// </summary>    public class DownloadBase {        protected readonly static List<string> loadedUri = new List<string>();        /// <summary>        /// 获取已下载完成的地址        /// </summary>        public static List<string> LoadedUri { get { return loadedUri; } }        /// <summary>        /// 下载失败(错误)次数        /// </summary>        public static int Error { get; protected set; }    }

ParallelDownloader    /// <summary>    /// 并行资源下载器    /// </summary>    public sealed class ParallelDownloader : DownloadBase {        /// <summary>        /// 资源下载进度中触发        /// </summary>        public event DownloadProgressChangedEventHandler DownloadProgressChanged;        /// <summary>        /// 资源下载完成        /// </summary>        public event OpenReadCompletedEventHandler OpenReadCompleted;        /// <summary>        /// 当前进度百分比        /// </summary>        public static int ProgressPercentage { get; private set; }        readonly static List<string> loadingUri = new List<string>();        readonly static List<string> waitingUri = new List<string>();        /// <summary>        /// 获取当前正在下载的地址        /// </summary>        public static List<string> LoadingUri { get { return loadingUri; } }        /// <summary>        /// 获取等待下载地址队列        /// </summary>        public static List<string> WaitingUri { get { return waitingUri; } }        /// <summary>        /// 下载资源文件        /// </summary>        /// <param name="uri">资源相对地址<</param>        /// <param name="userToken">资源参数</param>        /// <param name="waitingTime">如果正在被下载,等待检测时间(单位:毫秒)</param>        public void OpenReadAsync(string uri, object userToken, bool isWaiting, int waitingTime) {            if (loadedUri.Contains(uri)) {                Download(uri, userToken);            } else {                if (loadingUri.Contains(uri)) {                    //假如该资源正被下载中,则需要等待,每隔1秒检测一次是否已下载完成                    if (isWaiting) {                        DispatcherTimer timer = new DispatcherTimer() { Interval = TimeSpan.FromMilliseconds(waitingTime) };                        EventHandler handler = null;                        timer.Tick += handler = (s, e) => {                            if (loadedUri.Contains(uri)) {                                timer.Stop();                                timer.Tick -= handler;                                Download(uri, userToken);                            }                        };                        timer.Start();                    }                } else {                    if (!waitingUri.Contains(uri)) { waitingUri.Add(uri); }                    loadingUri.Add(uri);                    Download(uri, userToken);                }            }        }        /// <summary>        /// 开始下载        /// </summary>        /// <param name="uri">资源相对地址</param>        /// <param name="userToken">资源参数</param>        void Download(string uri, object userToken) {            OpenReadCompletedEventHandler openReadCompletedHandler = null;            DownloadProgressChangedEventHandler progressChangedHandler = null;            WebClient webClient = new WebClient();            webClient.DownloadProgressChanged += progressChangedHandler = (s, e) => {                ProgressPercentage = e.ProgressPercentage;                if (DownloadProgressChanged != null) { DownloadProgressChanged(this, e); }            };            webClient.OpenReadCompleted += openReadCompletedHandler = (s, e) => {                WebClient wc = s as WebClient;                wc.DownloadProgressChanged -= progressChangedHandler;                wc.OpenReadCompleted -= openReadCompletedHandler;                if (e.Error != null) {                    //断网处理,5秒后重试                    Error++;                    GlobalMethod.SetTimeout(delegate {                        Download(uri, userToken);                    }, 5000);                } else {                    waitingUri.Remove(uri);                    loadingUri.Remove(uri);                    if (!loadedUri.Contains(uri)) { loadedUri.Add(uri); }                    if (OpenReadCompleted != null) { OpenReadCompleted(this, e); }                }            };            webClient.OpenReadAsync(new Uri(uri, UriKind.Relative), userToken);        }    }

SerialDownloader     /// <summary>    /// 下载优先级    /// </summary>    public enum DownloadPriority {        /// <summary>        /// 最高        /// </summary>        Highest = 0,        /// <summary>        /// 高        /// </summary>        High = 1,        /// <summary>        /// 普通        /// </summary>        Normal = 2,        /// <summary>        /// 低        /// </summary>        Low = 3,        /// <summary>        /// 最低        /// </summary>        Lowest = 4,    }    /// <summary>    /// 串行资源下载器    /// </summary>    public class SerialDownloader : DownloadBase {        /// <summary>        /// 资源下载完成        /// </summary>        public static event OpenReadCompletedEventHandler OpenReadCompleted;        /// <summary>        /// 资源下载进度中触发        /// </summary>        public static event DownloadProgressChangedEventHandler DownloadProgressChanged;        /// <summary>        /// 当前进度百分比        /// </summary>        public static int ProgressPercentage { get; private set; }        static WebClient webClient = null;        readonly static List<string> loadingUri = new List<string>();        readonly static List<string> waitingUri = new List<string>();        /// <summary>        /// 获取当前正在下载的地址        /// </summary>        public static List<string> LoadingUri { get { return loadingUri; } }        /// <summary>        /// 获取等待下载地址队列        /// </summary>        public static List<string> WaitingUri { get { return waitingUri; } }        /// <summary>        /// 为Image图片控件设置图像源        /// </summary>        /// <param name="image">目标图片</param>        /// <param name="uri">图像源地址</param>        /// <param name="isWaiting">是否等待下载完成后再赋值</param>        public static void SetImageSource(Image image, string uri, DownloadPriority priority, bool isWaiting) {            if (loadedUri.Contains(uri)) {                image.Source = GlobalMethod.GetWebImage(uri);            } else {                image.Source = null;                AddUri(uri, priority);                if (isWaiting) {                    DispatcherTimer timer = new DispatcherTimer() { Interval = TimeSpan.FromMilliseconds(2000) };                    EventHandler handler = null;                    timer.Tick += handler = (s, e) => {                        if (loadedUri.Contains(uri)) {                            timer.Stop();                            timer.Tick -= handler;                            image.Source = GlobalMethod.GetWebImage(uri);                        }                    };                    timer.Start();                }            }        }        /// <summary>        /// 添加预备下载地址        /// </summary>        /// <param name="uri">图像源地址</param>        public static void AddUri(string uri, DownloadPriority priority) {            if (!waitingUri.Contains(uri)) { waitingUri.Insert((int)(((int)priority / 4d) * waitingUri.Count), uri); }            if (loadingUri.Count == 0) {                webClient = new WebClient();                webClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler(webClient_DownloadProgressChanged);                webClient.OpenReadCompleted += new OpenReadCompletedEventHandler(webClient_OpenReadCompleted);                webClient.OpenReadAsync(new Uri(GlobalMethod.WebPath(uri), UriKind.Relative), uri);                loadingUri.Add(uri);            }        }        static void webClient_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e) {            WebClient wc = sender as WebClient;            wc.DownloadProgressChanged -= webClient_DownloadProgressChanged;            wc.OpenReadCompleted -= webClient_OpenReadCompleted;            string uri = e.UserState.ToString();            if (e.Error != null) {                //断网处理,5秒后重试                Error++;                GlobalMethod.SetTimeout(delegate {                    loadingUri.Remove(uri);                    AddUri(uri, DownloadPriority.Highest);                }, 5000);            } else {                loadingUri.Remove(uri);                waitingUri.Remove(uri);                loadedUri.Add(uri);                if (waitingUri.Count > 0) { AddUri(waitingUri[0], DownloadPriority.Highest); }                if (OpenReadCompleted != null) { OpenReadCompleted(sender, e); }            }        }        static void webClient_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e) {            ProgressPercentage = e.ProgressPercentage;            if (DownloadProgressChanged != null) { DownloadProgressChanged(sender, e); }        }    }