c#限速下载网络文件的方法实例（c#限速下载网络文件的方法实例）

c#限速下载网络文件的方法，具体如下：

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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 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 爬虫 { public partial class form1 : form { #region 变量 /// <summary> /// 已完成字节数 /// </summary> private long completedcount = 0; /// <summary> /// 是否完成 /// </summary> private bool iscompleted = true; /// <summary> /// 数据块队列 /// </summary> private concurrentqueue<memorystream> msqueue = new concurrentqueue<memorystream>(); /// <summary> /// 下载开始位置 /// </summary> private long range = 0; /// <summary> /// 文件大小 /// </summary> private long total = 0; /// <summary> /// 一段时间内的完成节点数，计算网速用 /// </summary> private long unitcount = 0; /// <summary> /// 上次计时时间，计算网速用 /// </summary> private datetime lasttime = datetime.minvalue; /// <summary> /// 一段时间内的完成字节数，控制网速用 /// </summary> private long unitcountforlimit = 0; /// <summary> /// 上次计时时间，控制网速用 /// </summary> private datetime lasttimeforlimit = datetime.minvalue; /// <summary> /// 下载文件sleep时间，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) { } #endregion #region btndownload_click 下载 private void btndownload_click(object sender, eventargs e) { iscompleted = false; btndownload.enabled = false; string url = txturl.text.trim(); string filepath = createfilepath(url); #region 下载线程 thread thread = new thread(new threadstart(() => { int trytimes = 0; 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 = "请求服务器失败，重新请求" + trytimes.tostring() + "次"; })); httpdownloadfile(url, filepath); } })); thread.isbackground = true; thread.start(); #endregion #region 保存文件线程 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(); #endregion #region 计算网速/进度线程 thread = new thread(new threadstart(() => { while (!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 < 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 #region 显示进度 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("进度：{0}/{1}", completed, strtotal); lblbytemsg.text = string.format("已下载：{0}\r\n总大小：{1}", completedcount, total); if (completedcount == total) { messagebox.show("完成"); } })); #endregion } catch { } lasttime = datetime.now; unitcount = 0; } } })); thread.isbackground = true; thread.start(); #endregion #region 限制网速线程 thread = new thread(new threadstart(() => { while (!iscompleted) { thread.sleep(100); if (lasttimeforlimit != datetime.minvalue) { double sec = datetime.now.subtract(lasttimeforlimit).totalseconds; double speed = unitcountforlimit / sec / 1024; try { #region 限速/解除限速 double limitspeed = 0; if (double.tryparse(txtspeed.text.trim(), out limitspeed)) { if (speed > limitspeed && sleeptime < 1000) { sleeptime += 1; } if (speed < limitspeed - 10 && sleeptime >= 2) { sleeptime -= 1; } } else { this.invoke(new invokedelegate(() => { txtspeed.text = "100"; })); } #endregion } catch { } lasttimeforlimit = datetime.now; unitcountforlimit = 0; } } })); thread.isbackground = true; thread.start(); #endregion } #endregion #region httpdownloadfile 下载文件 /// <summary> /// http下载文件 /// </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; } // 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() as httpwebresponse; if (response.contentlength == range) { this.invoke(new invokedelegate(() => { lblmsg.text = "文件已下载"; })); return true; } // 设置参数 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); //发送请求并获取相应回应数据 response = request.getresponse() as httpwebresponse; //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 = new memorystream(); byte[] barr = new byte[1024]; lasttime = datetime.now; lasttimeforlimit = datetime.now; int size = responsestream.read(barr, 0, (int)barr.length); unitcount += size; unitcountforlimit += size; ms.write(barr, 0, size); while (!iscompleted) { size = responsestream.read(barr, 0, (int)barr.length); unitcount += size; unitcountforlimit += 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(); } thread.sleep(sleeptime); } responsestream.close(); return true; } catch (exception ex) { logutil.logerror(ex.message + "\r\n" + ex.stacktrace); return false; } } #endregion #region 根据url生成文件保存路径 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类 }