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代碼:
using System; using System.Collections.Concurrent; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.IO; using System.Linq; using System.Net; using System.Text; using System.Text.RegularExpressions; using System.Threading; using System.Threading.Tasks; using System.Windows.Forms; using Common.Utils; using Utils; namespace 爬蟲 { public partial class Form1 : Form { #region 變量 /// <summary> /// 已完成字節數 /// </summary> private long completedCount = 0; /// <summary> /// 能否完成 /// </summary> private bool isCompleted = true; /// <summary> /// 數據塊隊列 /// </summary> private ConcurrentQueue<MemoryStream> msQueue = new ConcurrentQueue<MemoryStream>(); /// <summary> /// 下載開端地位 /// </summary> private long range = 0; /// <summary> /// 文件大小 /// </summary> private long total = 0; /// <summary> /// 一段時間內的完成節點數,計算網速用 /// </summary> private long unitCount = 0; /// <summary> /// 上次計時時間,計算網速用 /// </summary> private DateTime lastTime = DateTime.MinValue; /// <summary> /// 下載文件sleep時間,控制速度用 /// </summary> private int sleepTime = 1; #endregion #region Form1 public Form1() { InitializeComponent(); } #endregion #region Form1_Load private void Form1_Load(object sender, EventArgs e) { lblMsg.Text = string.Empty; lblByteMsg.Text = string.Empty; lblSpeed.Text = string.Empty; } #endregion #region Form1_FormClosing private void Form1_FormClosing(object sender, FormClosingEventArgs e) { if (!isCompleted) { // e.Cancel = true; // MessageBox.Show("正在下載,不能封閉"); } } #endregion #region btnDownload_Click 下載 private void btnDownload_Click(object sender, EventArgs e) { isCompleted = false; btnDownload.Enabled = false; string url = txtUrl.Text.Trim(); string filePath = CreateFilePath(url); //下載線程 Thread thread = new Thread(new ThreadStart(() => { int tryTimes = 0; while (!HttpDownloadFile(url, filePath)) { this.Invoke(new InvokeDelegate(() => { lblMsg.Text = "下載出錯,嘗試重新開端" + (++tryTimes).ToString(); })); HttpDownloadFile(url, filePath); Thread.Sleep(1); } })); thread.IsBackground = true; thread.Start(); //保管文件線程 thread = new Thread(new ThreadStart(() => { while (!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 = true; } Thread.Sleep(1); } })); thread.IsBackground = true; thread.Start(); //計算網速線程 thread = new Thread(new ThreadStart(() => { while (!isCompleted) { Thread.Sleep(500); if (lastTime != DateTime.MinValue) { double sec = DateTime.Now.Subtract(lastTime).TotalSeconds; double speed = unitCount / sec / 1024; #region 限速/解除限速 double limitSpeed = 0; if (double.TryParse(txtSpeed.Text.Trim(), out limitSpeed)) { if (speed > limitSpeed && sleepTime < 1000) { sleepTime += 100; } if (speed < limitSpeed && sleepTime >= 2) { sleepTime /= 2; } } else { this.Invoke(new InvokeDelegate(() => { txtSpeed.Text = "100"; })); } #endregion #region 顯示速度 if (speed < 1024) { this.Invoke(new InvokeDelegate(() => { lblSpeed.Text = string.Format("{0}KB/S", speed.ToString("0.00")); })); } else { this.Invoke(new InvokeDelegate(() => { lblSpeed.Text = string.Format("{0}MB/S", (speed / 1024).ToString("0.00")); })); } #endregion lastTime = DateTime.Now; unitCount = 0; } } })); thread.IsBackground = true; thread.Start(); } #endregion #region HttpDownloadFile 下載文件 /// <summary> /// Http下載文件 /// </summary> public bool HttpDownloadFile(string url, string filePath) { try { if (!File.Exists(filePath)) { using (FileStream fs = new FileStream(filePath, FileMode.Create)) { fs.Close(); } } else { FileInfo fileInfo = new FileInfo(filePath); range = fileInfo.Length; } // 設置參數 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; //發送懇求並獲取相應回應數據 HttpWebResponse response = request.GetResponse() as HttpWebResponse; if (response.ContentLength == range) { this.Invoke(new InvokeDelegate(() => { lblMsg.Text = "文件已下載"; })); return true; } // 設置參數 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; request.AddRange(range); //發送懇求並獲取相應回應數據 response = request.GetResponse() as HttpWebResponse; response = request.GetResponse() as HttpWebResponse; //直到request.GetResponse()順序才開端向目的網頁發送Post懇求 Stream responseStream = response.GetResponseStream(); total = range + response.ContentLength; completedCount = range; MemoryStream ms = new MemoryStream(); byte[] bArr = new byte[1024]; lastTime = DateTime.Now; int size = responseStream.Read(bArr, 0, (int)bArr.Length); unitCount += size; ms.Write(bArr, 0, size); while (!isCompleted) { size = responseStream.Read(bArr, 0, (int)bArr.Length); unitCount += size; ms.Write(bArr, 0, size); if (ms.Length > 102400) { msQueue.Enqueue(ms); ms = new MemoryStream(); } if (completedCount + ms.Length == total) { msQueue.Enqueue(ms); ms = new MemoryStream(); } this.Invoke(new InvokeDelegate(() => { string strTotal = (total / 1024 / 1024).ToString("0.00") + "MB"; if (total < 1024 * 1024) { strTotal = (total / 1024).ToString("0.00") + "KB"; } string completed = (completedCount / 1024 / 1024).ToString("0.00") + "MB"; if (completedCount < 1024 * 1024) { completed = (completedCount / 1024).ToString("0.00") + "KB"; } lblMsg.Text = string.Format("進度:{0}/{1}", completed, strTotal); lblByteMsg.Text = string.Format("已下載:{0}\r\n總大小:{1}", completedCount, total); if (completedCount == total) { MessageBox.Show("完成"); } })); Thread.Sleep(sleepTime); } responseStream.Close(); return true; } catch { return false; } } #endregion #region 依據URL生成文件保管途徑 private string CreateFilePath(string url) { string path = Application.StartupPath + "\\download"; if (!Directory.Exists(path)) { Directory.CreateDirectory(path); } string fileName = Path.GetFileName(url); if (fileName.IndexOf("?") > 0) { return path + "\\" + fileName.Substring(0, fileName.IndexOf("?")); } else { return path + "\\" + fileName; } } #endregion } //end Form1類 }View Code