c# http下载 例子

参考链接：　　

类：

/************************************************************************************************************************/

  1 using system;
  2 using system.collections.generic;
  3 using system.io;
  4 using system.linq;
  5 using system.net;
  6 using system.text;
  7 using system.windows.forms;
  8 using system.threading.tasks;
  9 using system.threading;
 10 
 11 namespace httptool
 12 {
 13     class httphelper
 14     {
 15         const int bytebuff = 1024;
 16         const int readwritetimeout = 2 * 1000;//超时等待时间
 17         const int timeoutwait = 5 * 1000;//超时等待时间
 18         const int maxtrytime = 12;
 19 
 20         private double totalsize, curreadsize, speed;
 21         private int proc, remaintime;
 22         private int totaltime = 0;
 23 
 24         bool downloadworking = false;
 25 
 26         string strfilename = "";
 27         string strurl = "";
 28 
 29         string outmsg = "";
 30 
 31         public httphelper(string url, string savepath)
 32         {
 33             this.strurl = url;
 34             this.strfilename = savepath;
 35         }
 36 
 37         /// <summary>
 38         /// 下载数据更新
 39         /// </summary>
 40         /// <param name="totalnum">下载文件总大小</param>
 41         /// <param name="num">已下载文件大小</param>
 42         /// <param name="proc">下载进度百分比</param>
 43         /// <param name="speed">下载速度</param>
 44         /// <param name="remaintime">剩余下载时间</param>
 45         public delegate void deldownfilehandler(string totalnum, string num, int proc, string speed, string remaintime, string outmsg);
 46         public deldownfilehandler processshow;
 47         public delegate void deldowncompleted();
 48         public deldowncompleted processcompleted;
 49         public system.windows.forms.timer timer;
 50 
 51         public void init()
 52         {
 53             timer.interval = 100;
 54             timer.tick -= tickeventhandler;
 55             timer.tick += tickeventhandler;
 56             timer.enabled = true;
 57             downloadworking = true;
 58         }
 59 
 60         /// <summary>
 61         /// 获取文件大小
 62         /// </summary>
 63         /// <param name="size"></param>
 64         /// <returns></returns>
 65         private string getsize(double size)
 66         {
 67             string[] units = new string[] { "b", "kb", "mb", "gb", "tb", "pb" };
 68             double mod = 1024.0;
 69             int i = 0;
 70             while (size >= mod)
 71             {
 72                 size /= mod;
 73                 i++;
 74             }
 75             return math.round(size) + units[i];
 76         }
 77 
 78         /// <summary>
 79         /// 获取时间
 80         /// </summary>
 81         /// <param name="second"></param>
 82         /// <returns></returns>
 83         private string gettime(int second)
 84         {
 85             return new datetime(1970, 01, 01, 00, 00, 00).addseconds(second).tostring("hh:mm:ss");
 86         }
 87 
 88         /// <summary>
 89         /// 下载文件（同步）  支持断点续传
 90         /// </summary>
 91         public void dowloadfile()
 92         {
 93             totalsize = getfilecontentlength(strurl);
 94 
 95             //打开上次下载的文件或新建文件
 96             long lstartpos = 0;
 97             system.io.filestream fs;
 98             if (system.io.file.exists(strfilename))
 99             {
100                 fs = system.io.file.openwrite(strfilename);
101                 lstartpos = fs.length;
102                 fs.seek(lstartpos, system.io.seekorigin.current);   //移动文件流中的当前指针
103             }
104             else
105             {
106                 fs = new system.io.filestream(strfilename, system.io.filemode.create);
107                 lstartpos = 0;
108             }
109 
110             curreadsize = lstartpos;
111 
112             if (curreadsize == totalsize)
113             {
114                 outmsg = "文件已下载！";
115                 processcompleted?.invoke();
116                 timer.enabled = false;
117                 return;
118             }
119 
120             //打开网络连接
121             try
122             {
123                 system.net.httpwebrequest request = (system.net.httpwebrequest)system.net.httpwebrequest.create(strurl);
124                 if (lstartpos > 0)
125                     request.addrange((int)lstartpos);    //设置range值
126 
127                 //向服务器请求，获得服务器回应数据流
128                 system.io.stream ns = request.getresponse().getresponsestream();
129                 byte[] nbytes = new byte[bytebuff];
130                 int nreadsize = 0;
131                 proc = 0;
132 
133                 do
134                 {
135 
136                     nreadsize = ns.read(nbytes, 0, bytebuff);
137                     fs.write(nbytes, 0, nreadsize);
138 
139                     //已下载大小
140                     curreadsize += nreadsize;
141                     //进度百分比
142                     proc = (int)((curreadsize / totalsize) * 100);
143                     //下载速度
144                     speed = (curreadsize / totaltime) * 10;
145                     //剩余时间
146                     remaintime = (int)((totalsize / speed) - (totaltime / 10));
147 
148                     if (downloadworking == false)
149                         break;
150 
151                 } while (nreadsize > 0);
152 
153                 fs.close();
154                 ns.close();
155 
156                 if (curreadsize == totalsize)
157                 {
158                     outmsg = "下载完成！";
159                     processcompleted?.invoke();
160                     downloadworking = false;
161                 }
162             }
163             catch (exception ex)
164             {
165                 fs.close();
166                 outmsg = string.format("下载失败：{0}", ex.tostring());
167             }
168         }
169 
170         public void downloadpause()
171         {
172             outmsg = "下载已暂停";
173             downloadworking = false;
174         }
175 
176         public void downloadcontinue()
177         {
178             outmsg = "正在下载";
179             downloadworking = true;
180             downloadstart();
181         }
182 
183         public void downloadstart()
184         {
185             task.run(() =>
186             {
187                 dowloadfile();
188             });
189         }
190 
191 
192         /// <summary>
193         /// 定时器方法
194         /// </summary>
195         /// <param name="sender"></param>
196         /// <param name="e"></param>
197         private void tickeventhandler(object sender, eventargs e)
198         {
199             processshow?.invoke(getsize(totalsize),
200                                 getsize(curreadsize),
201                                 proc,
202                                 string.format("{0}/s", getsize(speed)),
203                                 gettime(remaintime),
204                                 outmsg
205                                 );
206             if (downloadworking == true)
207             {
208                 totaltime++;
209             }
210         }
211 
212         /// <summary>
213         /// 获取下载文件长度
214         /// </summary>
215         /// <param name="url"></param>
216         /// <returns></returns>
217         public long getfilecontentlength(string url)
218         {
219             httpwebrequest request = null;
220             try
221             {
222                 request = (httpwebrequest)httpwebrequest.create(url);
223                 //request.timeout = timeoutwait;
224                 //request.readwritetimeout = readwritetimeout;
225                 //向服务器请求，获得服务器回应数据流
226                 webresponse respone = request.getresponse();
227                 request.abort();
228                 return respone.contentlength;
229             }
230             catch (exception e)
231             {
232                 if (request != null)
233                     request.abort();
234                 return 0;
235             }
236         }
237     }
238 }

 

页面调用

/***************************************************************************************************************/

 1 using system;
 2 using system.collections.generic;
 3 using system.componentmodel;
 4 using system.data;
 5 using system.drawing;
 6 using system.linq;
 7 using system.text;
 8 using system.threading.tasks;
 9 using system.windows.forms;
10 using httptool;
11 using system.threading;
12 
13 namespace downloaddemo1
14 {
15     public partial class form1 : form
16     {
17         static string url = "http://speedtest.dallas.linode.com/100mb-dallas.bin"; //下载地址
18 
19         static string temp = system.environment.getenvironmentvariable("temp");
20         static string loadfilefolder = new system.io.directoryinfo(temp).fullname + @"\" + "100mb-dallas.bin";
21 
22         thread td;
23         httphelper httpmanager = new httphelper(url, loadfilefolder);
24 
25         public form1()
26         {
27             initializecomponent();
28         }
29 
30         private void form1_load(object sender, eventargs e)
31         {
32             httpmanager.timer = new system.windows.forms.timer();
33             httpmanager.processshow += processsho;
34             httpmanager.processcompleted += processcomplete;
35             httpmanager.init();
36 
37         }
38 
39         public void processsho(string totalnum, string num, int proc, string speed, string remaintime, string msg)
40         {
41             this.label1.text = string.format("文件大小：{0}", totalnum);
42             this.label2.text = string.format("已下载：{0}", num);
43             this.label3.text = string.format("进度：{0}%", proc);
44             this.label4.text = msg;
45             this.label5.text = string.format("速度：{0}",speed);
46             this.label6.text = string.format("剩余时间：{0}",remaintime);
47         }
48 
49         private void processcomplete()
50         {
51             messagebox.show("文件下载完成！", "提示");
52         }
53 
54         private void button1_click(object sender, eventargs e)
55         {
56             httpmanager.downloadstart();
57 
58         }
59 
60         private void button2_click(object sender, eventargs e)
61         {
62             httpmanager.downloadpause();
63         }
64 
65         private void button3_click(object sender, eventargs e)
66         {
67             httpmanager.downloadcontinue();
68         }
69     }
70 }

效果

/*********************************************************************************/