79 lines
3.3 KiB
C#
79 lines
3.3 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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using System.Windows.Forms;
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namespace TemuKJD.BLL.Tools
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{
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public class DownloadBLL
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{
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public static string downloadFile(string url, string fileName, Control ctrl)
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{
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if (ctrl == null)
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ctrl = new Control();
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//string StrFileName = "d:\\wgscd.zip"; //根据实际情况设置
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//string StrUrl = "https://files.cnblogs.com/files/wgscd/xxx.zip"; //根据实际情况设置
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string StrFileName = fileName;
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string StrUrl = url;
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//打开上次下载的文件或新建文件
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long lStartPos = 0;
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System.IO.FileStream fs;
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if (System.IO.File.Exists(StrFileName))//另外如果文件已经下载完毕，就不需要再断点续传了，不然请求的range 会不合法会抛出异常。
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{
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fs = System.IO.File.OpenWrite(StrFileName);
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lStartPos = fs.Length;
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fs.Seek(lStartPos, System.IO.SeekOrigin.Current); //移动文件流中的当前指针
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}
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else
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{
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fs = new System.IO.FileStream(StrFileName, System.IO.FileMode.Create);
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lStartPos = 0;
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}
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//打开网络连接
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try
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{
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System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(StrUrl);
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if (lStartPos > 0)
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{
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request.AddRange((int)lStartPos); // 设置Range值
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}
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System.Net.WebResponse response = request.GetResponse();
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//向服务器请求，获得服务器回应数据流
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System.IO.Stream ns = response.GetResponseStream();
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long totalSize = response.ContentLength;
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long hasDownSize = 0;
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byte[] nbytes = new byte[512];//521,2048 etc
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int nReadSize = 0;
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nReadSize = ns.Read(nbytes, 0, nbytes.Length);
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while (nReadSize > 0)
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{
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fs.Write(nbytes, 0, nReadSize);
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nReadSize = ns.Read(nbytes, 0, 512);
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hasDownSize += nReadSize;
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ctrl.Invoke(new Action(() =>
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{
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//ctrl.Text = "" + hasDownSize + "/" + totalSize + " (" + (((double)hasDownSize * 100 / totalSize).ToString("0.00")) + "%)"; // 显示下载百分比
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ctrl.Text = "正在下载模块 " + ((double)(hasDownSize + lStartPos) * 100 / (totalSize + lStartPos)).ToString("0.00") + "%"; // 显示下载百分比
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}));
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//Application.DoEvents();
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}
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fs.Close();
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ns.Close();
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ctrl.Invoke(new Action(() =>
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{
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ctrl.Text = "模块下载完成 " + ((double)(hasDownSize + lStartPos) * 100 / (totalSize + lStartPos)).ToString("0.00") + "%"; // 显示下载百分比
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}));
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return "下载完成";
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}
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catch (Exception ex)
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{
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fs.Close();
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return "下载过程中出现错误:" + ex.ToString();
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}
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}
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}
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}
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