实现http多线程下载文件代码,C#代码库,德仔网

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【C#】实现http多线程下载文件
作者: / 发布于2018/1/2/ 273
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.IO;
using System.Net;
using u32 = System.UInt32;
using s32 = System.Int32;
using f32 = System.Single;

namespace Test
{
    class Program
    {
        static readonly string mUrl = "http://127.0.0.1:8080//download";
        
        public class CDownloadFile
        {
            public CDownloadFile( string FileName, u32 FileSize )
            {
                mFileName = FileName;
                mFileSize = FileSize;
            }
            public string mFileName;
            public u32 mFileSize;
        }

        public class CThreadParam
        {
            public s32 mId;
            public string mFileName;
            public s32 mBeginBlock;
            public u32 mEndBlock;
            public ManualResetEvent mStartEvent;
            public ManualResetEvent mDoneEvent;
        }

        static void Main(string[] args)
        {
            //获取待下载文件大小本例就不写了比较简单略过，重点讨论下载部分
            //如存在下面待下载的文件
            List<CDownloadFile> DownloadFiles = new List<CDownloadFile>();
            DownloadFiles.Add(new CDownloadFile("1.rmvb", 123456));
            DownloadFiles.Add(new CDownloadFile("2.rmvb", 454578));

            //cpu核心数为线程数
            ManualResetEvent[] StartEvents = new ManualResetEvent[Environment.ProcessorCount];
            ManualResetEvent[] DoneEvents = new ManualResetEvent[Environment.ProcessorCount];
            CThreadParam[] Params = new CThreadParam[Environment.ProcessorCount];
            Thread[] Threads = new Thread[Environment.ProcessorCount];
            for (s32 i = 0; i < Environment.ProcessorCount; ++i)
            {
                StartEvents[i] = new ManualResetEvent(false);
                DoneEvents[i] = new ManualResetEvent(false);
                Params[i] = new CThreadParam();
                Params[i].mId = i;//线程ID
                Params[i].mStartEvent = StartEvents[i];//启动下载事件
                Params[i].mDoneEvent = DoneEvents[i];//完成下载事件
                Threads[i] = new Thread(new ParameterizedThreadStart(AsyncDownloadFile));
                Threads[i].Start(Params[i]);
            }

            //始终只有Environment.ProcessorCount多个线程在下载一个文件,你可以根据实际情况修改
            for (s32 i = 0; i < DownloadFiles.Count; ++i)
            {
                CDownloadFile f = DownloadFiles[i];

                //分配线程下载任务
                CutFile(Params, f.mFileSize);

                for (s32 j = 0; j < Environment.ProcessorCount; ++j)
                {
                    Params[j].mFileName = f.mFileName;
                    Params[j].mDoneEvent.Reset();//清空下载完成
                    Params[j].mStartEvent.Set();//启动线程
                }
                //等待下载中...
                WaitHandle.WaitAll(DoneEvents,-1);

                //将临时文件合并为完整文件
                MergeFile(Params);

                Console.WriteLine(f.mFileName + "下载完毕");
            }
        }
        //根据线程数量拆分文件大小计算每个线程下载文件大小块
        static void CutFile(CThreadParam[] Param, u32 FileSize)
        {
            //伐值，文件大小小于10MB没必要用多个线程下,根据实际情况调整
            if (FileSize < 1024 * 1024 * 10)
            {
                //从第0个字节下载到FileSize-1个字节，即整个文件大小
                Param[0].mBeginBlock = 0;
                Param[0].mEndBlock = FileSize-1;

                //其他的线程就设置一个标记表示没有启用
                for (s32 i = 1; i < Param.Length; ++i)
                {
                    Param[i].mBeginBlock = -1;
                }
            }
            else
            {
                //块大小
                u32 Block = FileSize / (u32)Param.Length;
                //每个线程计算自己的下载量
                for (u32 i = 0; i < Param.Length; ++i)
                {
                    Param[i].mBeginBlock = (s32)(i * Block);
                    Param[i].mEndBlock = (u32)Param[i].mBeginBlock + Block - 1;
                }
                //如果存在余数分配给最后一个线程
                Param[Param.Length - 1].mEndBlock += FileSize % (u32)Param.Length;
            }
        }

        static void AsyncDownloadFile(Object o)
        {
            var Param = (CThreadParam)o;

            HttpWebRequest Request;
            HttpWebResponse Response;

            Stream HttpStream;
            FileStream OutStream;

            s32 ReadBytes = 0;

            Byte[] Buffer = new Byte[1024];

            while (true)
            {
                Param.mStartEvent.WaitOne();
                if (-1 == Param.mBeginBlock)
                {
                    Param.mStartEvent.Reset();
                    Param.mDoneEvent.Set();
                    continue;
                }

                try
                {
                    //请求
                    Request = WebRequest.Create(mUrl + "//" + Param.mFileName) as HttpWebRequest;

                    //调整服务器上面文件指针（需要文件http服务器支持）
                    //题外话如果是支持断点续传也是调整这个值,判断临时文件是否存在即可，写本地文件的时候将文件指针指向最后即可(本例不讨论)
                    Request.AddRange(Param.mBeginBlock, Param.mEndBlock);

                    //得到响应
                    Response = Request.GetResponse() as HttpWebResponse;

                    //Response.StatusCode; 这个值为200表示一切OK
                    
                    HttpStream = Response.GetResponseStream();

                    //写入临时文件
                    OutStream = new FileStream( Param.mFileName + Param.mId.ToString(), FileMode.Create );
                    while (true)
                    {
                        ReadBytes = HttpStream.Read(Buffer, 0, Buffer.Length);
                        if (ReadBytes <= 0)
                        {
                            break;
                        }
                        OutStream.Write(Buffer, 0, ReadBytes);
                    }
                    OutStream.Close();
                    HttpStream.Close();
                    Response.Close();
                    Request.Abort();
                    Param.mStartEvent.Reset();
                    Param.mDoneEvent.Set();
                }
                catch (WebException e)
                {
                    //自行处理异常
                    Console.WriteLine(e.Message);
                }
                catch (Exception e)
                {
                    //自行处理异常
                    Console.WriteLine(e.Message);
                }
            }
        }

        static void MergeFile( CThreadParam[] Param )
        {
            //只有一个临时文件，即是完整文件,改掉文件名即可
            if (-1 == Param[1].mBeginBlock)
            {
                if (File.Exists(Param[0].mFileName))
                {
                    File.Delete(Param[0].mFileName);
                }
                File.Move(Param[0].mFileName + Param[0].mId.ToString(), Param[0].mFileName);
                return;
            }

            FileStream OutStream = new FileStream( Param[0].mFileName, FileMode.Create );
            FileStream InStream;
            Byte[] Buffer = new Byte[1024];
            s32 ReadBytes = 0;
            for (u32 i = 0; i < Param.Length; ++i)
            {
                //读取临时文件
                InStream = new FileStream(Param[i].mFileName + Param[i].mId.ToString(), FileMode.Open);
                while (true)
                {
                    ReadBytes = InStream.Read(Buffer, 0, Buffer.Length);
                    if (ReadBytes <= 0)
                    {
                        break;
                    }
                    OutStream.Write(Buffer, 0, ReadBytes);
                }
                InStream.Close();
                //删除临时文件
                File.Delete(Param[i].mFileName + Param[i].mId.ToString());
            }
            OutStream.Close();
        }
    }
}
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