C#限速下载网络文件

概述代码： using System; using System.Collections.Concurrent; using System.Collections.Generic; using Syste

代码：

using System; System.Collections.Concurrent; System.Collections.Generic; System.ComponentModel; System.Data; System.Drawing; System.IO; System.linq; System.Net; System.Text; System.Text.RegularExpressions; System.Threading; System.Threading.Tasks; System.windows.Forms; Common.Utils; Utils;namespace 爬虫{    public partial class Form1 : Form    {        #region 变量        /// <summary>        /// 已完成字节数        </summary>        private long completedCount = 0;         是否完成        bool isCompleted = true 数据块队列        private ConcurrentQueue<MemoryStream> msQueue = new ConcurrentQueue<MemoryStream>();         下载开始位置        long range =  文件大小        long total =  一段时间内的完成节点数，计算网速用        long unitCount =  上次计时时间，计算网速用        private DateTime lastTime = DateTime.MinValue;         一段时间内的完成字节数，控制网速用        long unitCountForlimit =  上次计时时间，控制网速用        private DateTime lastTimeForlimit = 下载文件sleep时间，控制速度用        int sleepTime = 1;        #endregion        #region Form1        public Form1()        {            InitializeComponent();        }        #region Form1_Load        voID Form1_Load(object sender,EventArgs e)        {            lblMsg.Text = string.Empty;            lblByteMsg.Text = .Empty;            lblSpeed.Text = .Empty;        }        #region Form1_FormClosing        voID Form1_FormClosing(#region btnDownload_Click 下载        voID btnDownload_Click(false;            btnDownload.Enabled = ;            string url = txtUrl.Text.Trim();            string filePath = CreatefilePath(url);            #region 下载线程            Thread thread = new Thread(new ThreadStart(() =>            {                int tryTimes = ;                while (!httpDownloadfile(url,filePath))                {                    Thread.Sleep(10000);                    tryTimes++;                    LogUtil.Log("请求服务器失败，重新请求" + tryTimes.ToString() + 次");                    this.Invoke(new InvokeDelegate(() =>                    {                        lblMsg.Text = ;                    }));                    httpDownloadfile(url,filePath);                }            }));            thread.IsBackground = ;            thread.Start();            #endregion            #region 保存文件线程            thread = isCompleted)                {                    MemoryStream ms;                    if (msQueue.TryDequeue(out ms))                    {                        using (fileStream fs = new fileStream(filePath,fileMode.Open,fileAccess.Write))                        {                            fs.Seek(completedCount,SeekOrigin.Begin);                            fs.Write(ms.ToArray(),0,(int)ms.Length);                            fs.Close();                        }                        completedCount += ms.Length;                    }                    if (total != 0 && total == completedCount)                    {                        Thread.Sleep(100);                        isCompleted = ;                    }                    Thread.Sleep();                }            }));            thread.IsBackground = #region 计算网速/进度线程isCompleted)                {                    Thread.Sleep(1000);                    if (lastTime != DateTime.MinValue)                    {                        double sec = DateTime.Now.Subtract(lastTime).TotalSeconds;                        double speed = unitCount / sec / 1024;                        try                        {                            #region 显示速度                            if (speed < )                            {                                                                {                                    lblSpeed.Text = string.Format({0}KB/S",speed.ToString(0.00));                                }));                            }                            else                            {                                {0}MB/S1024).ToString(#endregion                            #region 显示进度                            string strTotal = (total / 1024 / ") + MB;                                if (total < 1024 * )                                {                                    strTotal = (total / KB;                                }                                string completed = (completedCount / if (completedCount < )                                {                                    completed = (completedCount / ;                                }                                lblMsg.Text = 进度：{0}/{1},completed,strTotal);                                lblByteMsg.Text = 已下载：{0}\r\n总大小：{1}if (completedCount == total)                                {                                    MessageBox.Show(完成);                                }                            }));                            #endregion                        }                        catch { }                        lastTime = DateTime.Now;                        unitCount = ;                    }                }            }));            thread.IsBackground = #region 限制网速线程if (lastTimeForlimit != DateTime.Now.Subtract(lastTimeForlimit).TotalSeconds;                        double speed = unitCountForlimit / sec / #region 限速/解除限速                            double limitSpeed = ;                            if (double.TryParse(txtSpeed.Text.Trim(), limitSpeed))                            {                                if (speed > limitSpeed && sleepTime < )                                {                                    sleepTime += if (speed < limitSpeed - 10 && sleepTime >= 2)                                {                                    sleepTime -= ;                                }                            }                                                            {                                    txtSpeed.Text = 100;                                }));                            }                             { }                        lastTimeForlimit = DateTime.Now;                        unitCountForlimit =         }        #region httpDownloadfile 下载文件         http下载文件        bool httpDownloadfile(string url,1)"> filePath)        {            if (!file.Exists(filePath))                {                                    {                    fileInfo fileInfo =  fileInfo(filePath);                    range = fileInfo.Length;                }                // 设置参数                httpWebRequest request = WebRequest.Create(url) as httpWebRequest;                request.UserAgent = Mozilla/4.0 (compatible; MSIE 8.0; windows NT 6.0; TrIDent/4.0);                request.Proxy = null发送请求并获取相应回应数据                httpWebResponse response = request.GetResponse()  httpWebResponse;                if (response.ContentLength == range)                {                    文件已下载;                    }));                    return ;                }                 设置参数                request = WebRequest.Create(url) ;                request.AddRange(range);                发送请求并获取相应回应数据                response = request.GetResponse() 直到request.GetResponse()程序才开始向目标网页发送Post请求                Stream responseStream = response.GetResponseStream();                total = range + response.ContentLength;                completedCount = range;                MemoryStream ms =  MemoryStream();                byte[] barr = new byte[];                lastTime = DateTime.Now;                lastTimeForlimit = DateTime.Now;                int size = responseStream.Read(barr,)barr.Length);                unitCount += size;                unitCountForlimit += size;                ms.Write(barr,size);                isCompleted)                {                    size = responseStream.Read(barr,1)">)barr.Length);                    unitCount += size;                    unitCountForlimit += size;                    ms.Write(barr,size);                    if (ms.Length > 102400)                    {                        msQueue.Enqueue(ms);                        ms =  MemoryStream();                    }                    if (completedCount + ms.Length == total)                    {                        msQueue.Enqueue(ms);                        ms =  MemoryStream();                    }                    Thread.Sleep(sleepTime);                }                responseStream.Close();                ;            }             (Exception ex)            {                LogUtil.LogError(ex.Message + \r\n" + ex.StackTrace);                ;            }        }        #region 根据URL生成文件保存路径        string CreatefilePath( url)        {            string path = Application.StartupPath + \downloadDirectory.Exists(path))            {                Directory.CreateDirectory(path);            }            string filename = Path.Getfilename(url);            if (filename.IndexOf(?") > )            {                return path + \" + filename.Substring());            }             filename;            }        }            } end Form1类}

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测试截图：

 

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