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