查了下资料，Http断点续传主要是Http请求包中的Range头
多线程下载需要管理好每一个线程下载的文件段
整个代码大致如下
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using System;
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using ;
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using ;
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using ;
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using ;
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using ;
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using ;
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using ;
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using ;
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namespace FengBan
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{
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///
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/// 多线程下载、断点下载的管理类
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///
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class DFGManager : IDisposable
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{
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private string dfgFilename;
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private int size;
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private FileStream writer;
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private SortedSet
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rset = new SortedSet
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(new RangeCompare());
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///
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/// 多线程下载、断点下载的管理类
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///
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///
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internal DFGManager(string dfgFilename)
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{
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this.dfgFilename = dfgFilename;
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if ((dfgFilename))
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{
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ReadDFGFile();
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(dfgFilename);
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}
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writer = new FileStream(dfgFilename, );
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WriteDFGFile();
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}
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///
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/// 获取或设置要下载的文件大小
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///
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public int Size
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{
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get { return size; }
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set
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{
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size = value;
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byte[] head = new byte[16];
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byte[] bsize = (size);
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int i;
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for (i = 0; i < (); i++)
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{
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head[i] = bsize[i];
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}
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(0, );
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(head, 0, 16);
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();
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}
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}
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///
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/// 释放文件段，该段已经下载完成
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///
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///
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public void Free(Range range)
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{
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lock (rset)
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{
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var find = from r in rset
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where == && == 1
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select r;
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if (() == 1)
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{
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var ele = ();
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= 2;
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= 2;
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if ( < )
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{
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= ;
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}
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else
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{
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= ;
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}
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MergeRange();
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((), 0, 4);
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((), 0, 4);
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();
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}
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else if (() == 0)
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{
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throw new Exception("找不到释放的块");
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}
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else
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{
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throw new Exception("多个符合条件的块");
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}
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}
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}
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///
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/// 分配文件段
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///
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///
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期望分配的大小
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///
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实际分配的大小
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public Range Alloc(int expectSize = 102400)
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{
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lock (rset)
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{
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Range range = new Range();
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if ( == 0)
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{
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= 0;
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= (expectSize, this.size);
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= 1;
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(range);
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}
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else if ( == 1)
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{
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if (().left > 0)
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{
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= 0;
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= ().left;
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= 1;
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(range);
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}
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else if (().right < size)
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{
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= ().right;
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= (size, + expectSize);
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= 1;
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(range);
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}
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else
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{
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range = null;
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}
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}
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else
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{
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if (().left > 0)
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{
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= 0;
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= ().left;
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= 1;
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(range);
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}
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else if (().right < size)
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{
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= ().right;
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= (size, + expectSize);
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= 1;
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(range);
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}
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else
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{
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for (int i = 1; i < ; i++)
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{
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Range l = (i - 1);
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Range r = (i);
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if ( < )
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{
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= ;
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= ;
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= 1;
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(range);
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return range;
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}
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}
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range = null;
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}
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}
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return range;
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}
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}
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private void ReadDFGFile()
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{
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StreamReader reader = new StreamReader(dfgFilename);
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byte[] head = new byte[16];/*head占4个int*/
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(head, 0, 16);
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size = BitConverter.ToInt32(head, 0);
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byte[] buff = new byte[8];
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int rd = 0;
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do
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{
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rd = (buff, 0, 8);
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if (rd == 0)
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{
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break;
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}
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Range range = new Range();
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= BitConverter.ToInt32(buff, 0);
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= BitConverter.ToInt32(buff, 4);
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= 2;
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(range);
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}
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while (true);
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();
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MergeRange();
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}
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private void WriteDFGFile()
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{
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byte[] head = new byte[16];
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byte[] bsize = (size);
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int i;
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for (i = 0; i < (); i++)
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{
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head[i] = bsize[i];
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}
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(head, 0, 16);
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for (i = 0; i < ; i++)
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{
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Range r = (i);
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if ( == 2)
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{
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((), 0, 4);
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((), 0, 4);
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}
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}
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();
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}
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private void MergeRange()
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{
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int i;
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if ( >= 2)
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{
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Range last = ();
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for (i = 1; i < && >= 2; i++)
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{
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Range cur = (i);
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if ( <= && == 2 && == 2)
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{
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= ;
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(cur);
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i--;
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}
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else
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{
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last = cur;
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}
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}
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}
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}
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///
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/// 释放资源
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///
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public void Dispose()
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{
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if (writer != null)
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{
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();
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writer = null;
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}
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}
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~DFGManager()
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{
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Dispose();
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}
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}
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class Range
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{
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public int left;
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public int right;
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public int status;
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}
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class RangeCompare : IComparer
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{
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public int Compare(Range x, Range y)
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{
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return ( - );
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}
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}
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}
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using System;
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using ;
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using ;
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using ;
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using ;
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using ;
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using ;
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using ;
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using ;
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using ;
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namespace FengBan
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{
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class Program
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{
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static void Main()
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{
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MultiThreadDownload downloader = new MultiThreadDownload();
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("/sw-search-sp/soft/3a/12350/QQ_V7.0.14275.0_setup.", "");
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}
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}
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///
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/// 多线程下载类
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///
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class MultiThreadDownload
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{
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/*dfg文件记录下载好的文件段*/
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private const string suffix = ".dfg";
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private string site;/*文件下载地址*/
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private string outname;/*下载的文件名称*/
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private DFGManager dfgManager;/*文件分段下载管理对象*/
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private FileStream writer;/*多个下载子线程共用一个输出流*/
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/*通过currentDownload和lastDownload来实现限速*/
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private int currentDownload;
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private int lastDownload;
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private int shouldSleep;/*限速时应该休眠的时长，单位毫秒*/
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private timer;/*限速计时器*/
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/*上网代理*/
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public string ProxyAddressAndPort { get; set; }
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public string ProxyUserName { get; set; }
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public string ProxyPassword { get; set; }
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public MultiThreadDownload(int ThreadCount = 5)
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{
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this.ThreadCount = ThreadCount;
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timer = new (1000);
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+= CheckDownloadSpeed;
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= true;
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}
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///
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/// 下载文件的函数，仅支持http协议下载
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///
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///
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文件下载地址
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///
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输出文件名
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public void Download(string site, string outname)
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{
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string realname = outname;
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outname += ".down";
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this.site = site;
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this.outname = outname;
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try
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{
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/*根据需要设置代理*/
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if (ProxyEnable)
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{
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ICredentials cred = new NetworkCredential(ProxyUserName, ProxyPassword);
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WebProxy p = new WebProxy(ProxyAddressAndPort, true, null, cred);
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= p;
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}
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/*获取要下载的文件的信息,主要是获取文件大小*/
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HttpWebRequest request = (HttpWebRequest)(site);
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= "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.101 Safari/537.36";
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WebResponse response = ();
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Stream responseStream = ();
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long contentLength = ;
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("要下载的文件大小:{0}", contentLength);
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();
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();
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/*创建管理对象，负责给每一个线程分配下载的文件段*/
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dfgManager = new DFGManager(outname + suffix);
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= Convert.ToInt32(contentLength);
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currentDownload = 0;
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lastDownload = 0;
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writer = new FileStream(outname, );
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ManualResetEvent[] _ManualEvents = new ManualResetEvent[ThreadCount];
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//开启线程池下载
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for (int i = 0; i < ThreadCount; i++)
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{
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_ManualEvents[i] = new ManualResetEvent(false);
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(new WaitCallback(SDown), _ManualEvents[i]);
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}
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(_ManualEvents);/*等待子线程下载结束*/
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("全部下载子线程结束");
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//下载完成，释放资源
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();
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();
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/*收尾*/
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if ((realname))
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{
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(realname);
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}
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(outname, realname);
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(outname + suffix);
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}
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finally
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{
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}
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}
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private void CheckDownloadSpeed(object sender, e)
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{
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int curSpeed = (currentDownload - lastDownload);
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("当前速度 {0:f} kb/s", ((double)curSpeed) / 1000);
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lastDownload = currentDownload;
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//如果当前速度超过设定的速度，则应该执行限速动作
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//未实现
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}
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///
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/// 设置代理
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///
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///
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代理服务器地址和端口
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///
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代理服务器用户名
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///
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代理服务器密码
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public void SetProxy(string ProxyAddressAndPort, string Username, string Password)
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{
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this.ProxyAddressAndPort = ProxyAddressAndPort;
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this.ProxyUserName = Username;
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this.ProxyPassword = Password;
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this.ProxyEnable = true;
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}
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/*是否使用代理*/
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public bool ProxyEnable
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{
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get;
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set;
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}
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///
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/// 设置或获取多线程下载的数量
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///
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public int ThreadCount
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{
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set;
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get;
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}
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/*多线程下载的线程函数*/
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private void SDown(object param)
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{
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Range range;
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byte[] buff = null;
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/*从dfgManager中获取要下载的文件段*/
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while ((range = ()) != null)
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{
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HttpWebRequest request = (HttpWebRequest)(site);
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(, );
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= "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.101 Safari/537.36";
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WebResponse response = ();
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int contentLength = (int);
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//分配下载的缓存空间
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if (buff == null || () < contentLength)
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{
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buff = new byte[contentLength];
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}
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//使用while循环读取全部字节到buff中
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int count = 0;
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while (count < contentLength)
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{
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count += ().Read(buff, count, (int)contentLength - count);
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}
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//真正从服务器下载下来的文件段
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Range realRange = new Range();
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= ;
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= ( + count, );
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(realRange);
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();
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//将buff写入文件
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(, );
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(buff, 0, - );
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();
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int realDown = - ;
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currentDownload += realDown;
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("本次分段下载大小{0}", realDown);
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if (LimitSpeed > 0 && shouldSleep > 10)
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{
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("休眠{0}", shouldSleep);
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(shouldSleep);
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}
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}
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("线程执行结束");
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/*通知主线程执行完成*/
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ManualResetEvent e = (ManualResetEvent)param;
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();
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}
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private int xiansu;
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///
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/// 表示是否限速,0表示不限速,单位 b/s
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///
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public int LimitSpeed
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{
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get
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{
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return xiansu;
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}
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set
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{
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xiansu = value;
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if (value > 0)
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{
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= true;
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}
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}
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}
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}
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}
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