c#实现多线程复制文件

2025-02-22 00:59:24

推荐回答（3个）

回答1：

using System;
using System.Threading;
using System.IO;

namespace CopyTest
{

//FileBuffer用来存放和取出缓冲区变量
public class FileBuffer
{
private int m_readsize = 1024;
//定义了m_capacity个字节的缓冲区
private byte[] m_buffer = new byte[4096];
//确认缓冲区内已放字节的个数
private int bufferCount = 0;
//确定读写的位置
private int readLocation = 0, writeLocation = 0;

public FileBuffer()
{

}

//从缓冲区中取数据
public byte[] getBuffer()
{
//加上了共享锁
lock (this)
{
//判断如果缓冲区内无内容,则读取者进入wait状态,并且释放对象锁
if (bufferCount == 0)
{
Console.WriteLine("缓冲区无数据,无法读取");
Monitor.Wait(this);
}

byte[] newBuf = new byte[m_readsize];
Buffer.BlockCopy(m_buffer, readLocation, newBuf, 0, m_readsize);

//已经从缓冲区读取了内容,所以bufferCount要进行自减.
bufferCount -= m_readsize;
//求余的目的是为了循环使用缓冲区
readLocation = (readLocation + m_readsize) % m_buffer.Length;
//通知对象的第一个等待线程可以从WaitSleepJoin转换到Started状态.
Monitor.Pulse(this);
//返回给读取者取出的数值
return newBuf;
}
}

//将数据放入缓冲区
public void setBuffer(byte[] writeValue)
{
//锁住共享数据区
lock (this)
{
//如果缓冲区已满,那么进入waitsleepjoin状态
if (bufferCount == m_buffer.Length)
{
Console.WriteLine("缓冲区溢出!");
Monitor.Wait(this);
}
//向缓冲区写入数据
Buffer.BlockCopy(writeValue, 0, m_buffer, writeLocation, m_readsize);
//自加,代表缓冲区现在到底有几个数据
bufferCount += m_readsize;
//用%实现缓冲区的循环利用
writeLocation = (writeLocation + m_readsize) % m_buffer.Length;
//唤醒waitSleepJoin状态的进程,到started状态
Monitor.Pulse(this);
}//使用lock隐式的释放了共享锁
}
}

//写入者类,向缓冲区中放入数据
public class Writer
{
//定义了同步变量
FileBuffer shared;
FileStream file;
//此处构造函数的作用是在启动类中调用写入者的时候,把启动类中定义的sharedLocation传过来
public Writer(FileBuffer sharedLocation)
{
file = new FileStream("C:\\Test.txt", FileMode.Open);
shared = sharedLocation;
}
//定义写入过程
public void Write()
{
//将数据放入缓冲区
Byte[] datas = new byte[1024];

for (int byteread = 0; byteread <= file.Length; byteread += datas.Length)
{
file.Read(datas, byteread, datas.Length);
shared.setBuffer(datas);
}

file.Close();

//得到当前线程的名字
string name = Thread.CurrentThread.Name;
//此线程执行完毕
Console.WriteLine(name + "done writeing");
}
}

public class Reader
{//定义读取者
byte[] value;
FileStream file;
//定义同步变量
FileBuffer shared;
//定义构造函数,负责传递启动类中的shared
public Reader(FileBuffer sharedLocation)
{
file = new FileStream("C:\\Data.txt", FileMode.Create);
shared = sharedLocation;
}

public void Read()
{
//从缓冲区中循环读取
for (int bytewrite = 0; bytewrite <= 65535; )
{
value = shared.getBuffer();
file.Write(value, bytewrite, value.Length);
bytewrite += value.Length;
}

file.Close();

//取得当前线程的名字
string name = Thread.CurrentThread.Name;
Console.WriteLine(name + "done reading");
}
}

public class ThreadTest
{ //设置为启动类
public static void Main()
{
FileBuffer shared = new FileBuffer();
//初始化了写入者和读取者,并且把shared参数传递了过去
Writer Writer1 = new Writer(shared);
Reader Reader1 = new Reader(shared);

Thread WriterThread = new Thread(new ThreadStart(Writer1.Write));
WriterThread.Name = "写入者";

Thread ReaderThread = new Thread(new ThreadStart(Reader1.Read));
ReaderThread.Name = "读取者";
//启动这两个线程
WriterThread.Start();
ReaderThread.Start();
WriterThread.Join();
ReaderThread.Join();
Console.ReadLine();
}
}
}

回答2：

多个线程复制同一个文件，这样会越来越慢吧，相比单线程，做了更多的事，怎么可能更快呢？

回答3：

文件复制不是下载多线程有用吗，复制速度是与硬件有关的

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