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Linux socket编程（五） 文件传输

第七根弦 2014 年 7 月 14 日 未分类 发表评论 (0)

这一篇给之前写的聊天室再加上文件传输。

以下是对文件操作的封装
FileOperator.h

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#ifndef FILEOPERATOR_H
#define FILEOPERATOR_H
 
#include <stdio.h>
 
#define WRITE_CREATE_MODE "a+b"
 
#include <fcntl.h>
#include <string>
 
class FileOperator
{
    public:
        FileOperator();
        ~FileOperator();
        bool Open(const char* fileName,const char* option);
        int WriteToFile(const std::string& buffer);
        int ReadFromFile(std::string& buffer);
        void Close();
 
    private:
        FILE* filePtr;
};
 
#endif

FileOperator.cpp

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#include "FileOperator.h"
#include <sys/sendfile.h>
#include <memory.h>
 
const int MAX_BUFFERLENGTH=512;
 
FileOperator::FileOperator()
:filePtr(NULL)
{}
 
FileOperator::~FileOperator()
{
    Close();
}
 
bool FileOperator::Open(const char* fileName,const char* option)
{
    filePtr=fopen(fileName,option);
    return filePtr!=NULL;
}
 
 
int FileOperator::WriteToFile(const std::string& buffer)
{
    int writeBytes=::fwrite(buffer.c_str(),sizeof(char),buffer.size(),filePtr);
 
    if(writeBytes<0)
    {
        perror("error from fwrite");
        return -1;
    }
    else if(writeBytes==0)
            return 0;
    else
        return writeBytes;
}
 
int FileOperator::ReadFromFile(std::string& buffer)
{
    char bufferArray[MAX_BUFFERLENGTH+1];
    buffer.clear();
    memset(bufferArray,0,MAX_BUFFERLENGTH+1);
 
    int numberRead=fread(bufferArray,sizeof(char),MAX_BUFFERLENGTH+1,filePtr);
    if(numberRead==-1)
    {
        perror("error in Socket::Receive");
        return -1;
    }
    else if(numberRead==0)
        return 0;
    else
    {
        buffer=bufferArray;
        return numberRead;
    }
}
 
void FileOperator::Close()
{
    if(filePtr!=NULL)
        fclose(filePtr);
}

那怎么发送文件呢

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void ClientSocket::SendFile(const std::string& fileName)
{
    FileOperator fileOperator;
    fileOperator.Open(fileName.c_str(),"rb");
    std::string buffer;
 
    int readBytes;
    Send("File");
 
    while((readBytes = fileOperator.ReadFromFile(buffer))>0)
    {
        if(Send(buffer)<0)
        {
            perror("failed to send file");
            break;
        }
    }
 
}

接收文件

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void ServerSocket::RecvFile(Socket* clientSocket)
{
    std::string message;
    FileOperator fileOperator;
    //using IP address to name received file
    fileOperator.Open(clientSocket->GetAddress().c_str(),WRITE_CREATE_MODE);
 
    int recvBytes;
    int writeBytes;
 
    while((recvBytes=Socket::Receive(*clientSocket,message))>0)
    {
        std::cout<<"message length: "<<message.size()<<"\n";
        writeBytes=fileOperator.WriteToFile(message);
        std::cout<<"writeBytes: "<<writeBytes<<"\n";
 
        if(writeBytes<recvBytes)
        {
            perror("write to file failed");
            Socket::Send(*clientSocket,"Error when server receiving file.");
            return;
        }
 
        //if all bytes has been wrote
        if(recvBytes==0 || recvBytes!=MAXRECEIVE)
            break;
 
    }
 
    if(recvBytes >=0 )
        Socket::Send(*clientSocket,"server has received your file.");
}

要注意的是发送文件时，如果文件较大，客户端很可能会阻塞，这个时候可以开一个新线程来发送文件。
不过，这个只是很简单的文件传输，复杂点的有空再慢慢研究。

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