该下载模块总共会多开两个线程，一个下载线程和一个计时器线程，计时器线程主要用来计算每秒的下载速度。考虑版本兼容的问题没用使用await/async，而是使用传统的Thread。
用法:
|
1 2 3 4 5 |
Downloader d = new Downloader(); d.SetTask("https://dl.360safe.com/setup.exe", @"F:\360.exe"); d.Start(); //当下载线程下载完毕后记得调用 d.Dispose(); |
源代码：
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 |
using System; using System.IO; using System.Net; using System.Threading; namespace com.imxqy.net { public sealed class Downloader : IDisposable { public enum DownloadState { None, Download, Pause, Finish, } //目标文件地址 public string TargetURL { get; private set; } //目标文件大小 public long TargetLength { get; private set; } //下载的本地文件路径 public string LocalFilePath { get; private set; } //已经下载的本地文件大小 public long DownloadedLength { get; private set; } //下载速度 public int Speed { get; private set; } private long lastDownloadLength; private Timer timer; private DownloadState state = DownloadState.None; public DownloadState State { get => this.state; private set { this.state = value; this.StateHandler?.Invoke(value); } } //状态委托 public event Action<DownloadState> StateHandler; //下载时的文件名 private string downloadingName = string.Empty; //下载时的额外后缀名 private const string DOWNLOADING_FILE_EXT = ".jxdown"; private Thread downloadThread = null; //设置下载任务 public void SetTask(string targetURL, string localPath) { this.Reset(); this.TargetURL = targetURL; this.LocalFilePath = localPath; } //重置 private void Reset() { this.State = DownloadState.None; this.DownloadedLength = 0; this.lastDownloadLength = 0; this.Speed = 0; } //开始 public void Start() { if (this.State == DownloadState.Download) return; this.State = DownloadState.Download; if (this.downloadThread == null) { this.downloadThread = new Thread(this.DownloadThread); } //开启下载线程 this.downloadThread.IsBackground = false; this.downloadThread.Start(this); //开启速度计时器线程 if (this.timer == null) { this.timer = new Timer((sender) => { Downloader self = (Downloader)sender; var distance = self.DownloadedLength - self.lastDownloadLength; self.Speed = (int)distance; self.lastDownloadLength = self.DownloadedLength; }, this, -1, 0); } this.timer.Change(0, 1000); } //下载线程 private void DownloadThread(object _this) { Downloader self = (Downloader)_this; self.downloadingName = self.LocalFilePath + DOWNLOADING_FILE_EXT; if (File.Exists(self.LocalFilePath)) { //TODO 下载完成 self.State = DownloadState.Finish; return; } //获取长度 self.TargetLength = Http.GetHttpFileLenght(self.TargetURL); //获取远程文件流 HttpWebRequest httpWebRequest = HttpWebRequest.Create(self.TargetURL) as HttpWebRequest; //本地文件流 FileStream fs = null; if (File.Exists(self.downloadingName)) { //断点续传 fs = new FileStream(self.downloadingName, FileMode.Open); self.DownloadedLength = fs.Length; //移动指针 fs.Seek(fs.Length, SeekOrigin.Current); //请求续传 httpWebRequest.AddRange(fs.Length); } else { //创建新文件 fs = new FileStream(self.downloadingName, FileMode.Create); } //下载 Stream downStream = httpWebRequest.GetResponse().GetResponseStream(); const int chunkSize = 409600; // 400kb byte[] buf = new byte[chunkSize]; int size = 0; while (self.state == DownloadState.Download && (size = downStream.Read(buf, 0, chunkSize)) > 0) { //写文件流 fs.Write(buf, 0, size); fs.Flush(); self.DownloadedLength += size; } fs.Close(); downStream.Close(); self.Finish(); } private void Finish() { File.Move(this.downloadingName, this.LocalFilePath); this.State = DownloadState.Finish; } public void Pause() { this.State = DownloadState.Pause; this.timer.Change(-1, 0); } public void Dispose() { if (this.downloadThread != null) { this.downloadThread.Abort(); this.downloadThread = null; } this.timer.Dispose(); this.timer = null; GC.SuppressFinalize(this); } } } |
文章评论