C#实现文件下载，支持断点续传,C#代码片段分享, – 脚本分享网

C#实现文件下载，支持断点续传。本文非常不错。

 

 

 

 

 

 

 

 

 

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using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.IO;
using System.Text;
using System.Net;
namespace simpleDemo
{
    
    class Program
    {
        /// <summary>
        /// 下载文件保留字
        /// </summary>
        public static string PERSIST_EXP = ".cdel";
        /// <summary> 
        public static void Main(string[] args)
        {
            string path = "D:\\aa.txt";
            string ec = getFileEncoding(path, "GB2312");
            print("coding: " + ec);
            // string content = fileReader(path, Encoding.GetEncoding(ec));
            // print(content);
            //fileWriter(path, "测试内容11", Encoding.GetEncoding(ec));
            string url = "http://www.XXX.com/20120920172200024.flv";
            string path1 = "D:\\aa1.flv";
            download(url, path1);
            //gapDownload(url, path1);
            //t(url);
           
        }
        public static void t(string url) {
            
            HttpWebRequest request = (System.Net.HttpWebRequest)HttpWebRequest.Create(url);
            //WebResponse response = httpClient.CreateGetHttpResponse(url, 3000, null, null);
            try {
                
                WebResponse response = request.GetResponse();
                WebHeaderCollection headers = response.Headers;
                print(response.ContentLength);
                request = (System.Net.HttpWebRequest)HttpWebRequest.Create(url);
                request.AddRange(11); //设置Range值
                WebResponse response1 = request.GetResponse();
                print(response1.ContentLength);
                foreach (string key in headers)
                {
                    print(key + "----- " + headers.Get(key));
                }
                string disposition = headers.Get("Content-Disposition");
                print(disposition);
            }catch(Exception e){
                print(e.Message);
            }
            //string fileName = disposition.Substring(disposition.IndexOf("\""));
            //print(fileName);
          
        }
        public static void download(string url, string path) {
            if (File.Exists(path))
            {
                print("文件己存在！是否重新下载？");
                return;
            }
            else {
                path = path + PERSIST_EXP;
                simpleDownload(url,path);//开始下载
            }  
        }
        /// <summary>
        /// 下载网络资源(支持断点续传)
        /// </summary>
        /// <param name="url"></param>
        /// <param name="path"></param>
        public static void simpleDownload(string url, string path)
        {
            HttpWebRequest request = httpClient.getWebRequest(url, 0);
            
            WebResponse response = null;
            FileStream writer = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write);
            long lStartPos = writer.Length; ;//当前文件大小
            long currentLength = 0;
            long totalLength = 0;//总大小
            
            if (File.Exists(path))//断点续传
            {
                response = request.GetResponse();
                long sTotal = response.ContentLength;
                if (sTotal == lStartPos) {
                    close(writer);
                    File.Move(path, path.Replace(PERSIST_EXP, ""));
                    print("下载完成!");
                    return;
                }
                request = httpClient.getWebRequest(url, (int)lStartPos);//设置Range值
                writer.Seek(lStartPos, SeekOrigin.Begin);//指针跳转
                response = request.GetResponse();
                totalLength = response.ContentLength + lStartPos; //总长度
                currentLength = lStartPos; //当前长度
            }
            else
            {
                response = request.GetResponse();
                totalLength = response.ContentLength;
            }
            Stream reader = response.GetResponseStream();
            byte[] buff = new byte[1024];
            int c = 0; //实际读取的字节数
            while ((c = reader.Read(buff, 0, buff.Length)) > 0)
            {
                currentLength += c;
                writer.Write(buff, 0, c);
                progressBar(currentLength, totalLength);//进度条
                writer.Flush();
            }
            close(writer);
            if (currentLength == totalLength)
            {
                File.Move(path, path.Replace(PERSIST_EXP, ""));
                print("下载完成!");
            }
         
            if (reader != null)
            {
                reader.Close();
                reader.Dispose();
                response.Close();
            }
        }
        private static void close(FileStream writer)
        {
            if (writer != null)
            {
                writer.Close();
                writer.Dispose();
            }
        }
        /// <summary>
        /// 进度条
        /// </summary>
        /// <param name="currentLength">当前长度</param>
        /// <param name="totalLength">总长度</param>
        public static void progressBar(Object currentLength, Object totalLength)
        {
            double aaa = System.Convert.ToDouble(currentLength);
            double bbb = System.Convert.ToDouble(totalLength);
            print(currentLength + "/" + totalLength + "__" + (aaa / bbb).ToString("0.00 %"));
        }
        /// <summary>
        /// 系统输出
        /// </summary>
        /// <param name="obj"></param>
        public static void print(Object obj){
            Console.WriteLine(obj);
        }
        public static void printStr(string[] str)
        {
            foreach (string d in str)
            {
                print(d);
            }
        }
        /// <summary>
        /// 文件写
        /// </summary>
        /// <param name="path">文件路径</param>
        /// <param name="content">要写入的内容</param>
        public static void fileWriter(string path,string content,Encoding encoding)
        {
            if (File.Exists(path))
            {
                StreamWriter sw = new StreamWriter(path, true, encoding);
                
                sw.WriteLine(content);
                sw.Flush();
                sw.Close();
            }
        }
        /// <summary>
        /// 读文件，返回内容
        /// </summary>
        /// <param name="path">文件路径</param>
        /// <param name="enCoding">默认编码格式</param>
        /// <returns></returns>
        public static string fileReader(string path,Encoding enCoding) {
            StringBuilder sb = new StringBuilder();
            if(enCoding == null){
                enCoding = Encoding.Default;
            }
            //读取文件
            StreamReader sr = new StreamReader(path, enCoding);
                string s = "";
                while ((s = sr.ReadLine()) != null)
                {
                    sb.AppendLine(s);
                }
                if(sr != null)
                    sr.Close();
            return sb.ToString();
        }
        /// <summary>
        /// 获取文件编码格式
        /// </summary>
        /// <param name="path">文件路径</param>
        /// <param name="defaultEncoding">默认编码</param>
        /// <returns></returns>
        public static string getFileEncoding(string path, string defaultEncoding) {
            string ed = defaultEncoding;
            if (File.Exists(path)) {
                FileStream fs = new FileStream(path, FileMode.Open);
                ed = GetEncoding(fs, defaultEncoding);
                if (fs != null)
                    fs.Close();  
            }
            return ed;
        }
        /// <summary>
        /// 取得一个文本文件流的编码方式。
        /// </summary>
        /// <param name="stream">文本文件流。</param>
        /// <param name="defaultEncoding">默认编码方式。当该方法无法从文件的头部取得有效的前导符时，将返回该编码方式。</param>
        /// <returns></returns>
        public static string GetEncoding(FileStream stream, string defaultEncoding)
        {
            string targetEncoding = defaultEncoding;
            if (stream != null && stream.Length >= 2)
            {
                //保存文件流的前4个字节
                byte byte1 = 0;
                byte byte2 = 0;
                byte byte3 = 0;
                byte byte4 = 0;
                //保存当前Seek位置
                long origPos = stream.Seek(0, SeekOrigin.Begin);
                stream.Seek(0, SeekOrigin.Begin);
                int nByte = stream.ReadByte();
                byte1 = Convert.ToByte(nByte);
                byte2 = Convert.ToByte(stream.ReadByte());
                if (stream.Length >= 3)
                {
                    byte3 = Convert.ToByte(stream.ReadByte());
                }
                if (stream.Length >= 4)
                {
                    byte4 = Convert.ToByte(stream.ReadByte());
                }
                //根据文件流的前4个字节判断Encoding
                //Unicode {0xFF, 0xFE};
                //BE-Unicode {0xFE, 0xFF};
                //UTF8 = {0xEF, 0xBB, 0xBF};
                if (byte1 == 0xFE && byte2 == 0xFF)//UnicodeBe
                {
                    targetEncoding = Encoding.BigEndianUnicode.BodyName;
                }
                if (byte1 == 0xFF && byte2 == 0xFE && byte3 != 0xFF)//Unicode
                {
                    targetEncoding = Encoding.Unicode.BodyName;
                }
                if (byte1 == 0xEF && byte2 == 0xBB && byte3 == 0xBF)//UTF8
                {
                    targetEncoding = Encoding.UTF8.BodyName;
                }
                //恢复Seek位置
                stream.Seek(origPos, SeekOrigin.Begin);
            }
            return targetEncoding;
        }
    }
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using System.IO;
namespace simpleDemo
{
    /// <summary>
    /// 公用 Http 请求类
    /// </summary>
    class httpClient
    {
        /// <summary>
        /// 获取基础WebRequest
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="lStartPos">请求的开始位置</param>
        /// <returns></returns>
        public static HttpWebRequest getWebRequest(string url, int lStartPos)
        {
            HttpWebRequest request = null;
            try
            {
                request = (System.Net.HttpWebRequest)HttpWebRequest.Create(url);
                request.AddRange(lStartPos); //设置Range值
            }
            catch (Exception ex)
            {
                Program.print(ex.Message);
            }
            return request;
        }
    }
}
//该代码片段来自于: http://www.sharejs.com/codes/csharp/5646

来源URL：http://www.sharejs.com/codes/csharp/5646