Linux socket编程（一） 对套接字操作的封装

以前写的，现在回顾一下：
下面是对socket操作的封装，因为在Linux下写中文到了windows里面会乱码，所以注释用英文来写，有空再查下解决方法吧
socket.h

#ifndef SOCKET_H
#define SOCKET_H

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string>

const int MAXCONNECTION=5;
const int MAXRECEIVE = 500;

class Socket
{
public:
Socket();
//virtual destructior
virtual ~Socket();

// Server initialization
bool Create(); //create a socket
bool Bind(const int port);
bool Listen() const;
bool Accept(Socket& clientSocket) const;

// Client initialization
bool Connect(const std::string& host,const int port);

// Data Transmission
bool Send(Socket& socket,const std::string& message) const;
int Receive(Socket& socket,std::string& message) const;

void SetNonBlocking(const bool flag);
bool IsValid() const;

private:
//use m_sockfd to record the result of function socket
int m_sockfd;
struct sockaddr_in m_address;
};

#endif

这里解释下为什么析构函数是虚的，如果要用到多态的话，也就是用一个指向基类的指针来处理对不同到对象
如果类的成员函数不是虚函数，只是个普通的函数，那么会出现一种静态绑定到情况，如
Base* pBase = new Derive; //这里Base的析构函数不是虚函数
delete pBase; //这里只会调用Base::~Base()，所以派生类部分的资源将得不到释放
如果析构函数是虚函数的话，那么将调用Derive::~Derive()，由于我们提供了派生类的析构函数，编译器会扩展这个析构函数，
在里面调用基类的析构函数，这样派生类和基类的资源都将得到释放
 
socket.cpp

#include "Socket.h"
#include <stdlib.h>
#include <memory.h>
#include <iostream>
#include <fcntl.h>

Socket::Socket()
:m_sockfd(-1)
{
}

Socket::~Socket()
{
if(IsValid())
::close(m_sockfd);
}

//server function
bool Socket::Create()
{
m_sockfd=socket(AF_INET,SOCK_STREAM,0);
if(!IsValid())
return false;
return true;
}

bool Socket::Bind(const int port)
{
if(!IsValid())
return false;

m_address.sin_family=AF_INET;
m_address.sin_addr.s_addr = htonl(INADDR_ANY);
m_address.sin_port=htons(port);

int bindReturn=bind(m_sockfd,(struct sockaddr*)&m_address,sizeof(m_address));
if(bindReturn==-1)
return false;

return true;
}

bool Socket::Listen()const
{
if(!IsValid())
return false;
int listenReturn=listen(m_sockfd,MAXCONNECTION);
if(listenReturn ==-1)
return false;
return true;
}

bool Socket::Accept(Socket& clientSocket) const
{
int clientaddrLength=sizeof(clientSocket.m_address);
clientSocket.m_sockfd=::accept(m_sockfd,(struct sockaddr*)&clientSocket.m_address,(socklen_t *)&clientaddrLength);

if(clientSocket.m_sockfd==-1)
return false;
return true;
}
//end server functions

bool Socket::Connect(const std::string& host,const int port)
{
if(!IsValid())
return false;

m_address.sin_family=AF_INET;
m_address.sin_port=htons(port);
m_address.sin_addr.s_addr=inet_addr(host.c_str());

int connectReturn=::connect(m_sockfd,(struct sockaddr*)&m_address,sizeof(m_address));
if(connectReturn==-1)
return false;
return true;

}

// Data Transmission
bool Socket::Send(Socket& socket,const std::string& message) const
{
int result=::send(socket.m_sockfd,message.c_str(),message.length(),MSG_NOSIGNAL);
if(result==-1)
return false;
return true;
}

int Socket::Receive(Socket& socket,std::string& message) const
{
char buffer[MAXRECEIVE+1];
message.clear();
memset(buffer,0,MAXRECEIVE+1);

int numberRead=::recv(socket.m_sockfd,buffer,MAXRECEIVE,0);
if(numberRead==-1)
{
std::cout<<"error in Socket::Receive\n";
return 0;
}
else if(numberRead==0)
return 0;
else
{
message=buffer;
return numberRead;
}

}

void Socket::SetNonBlocking(const bool flag)
{
    if(IsValid())
    {
          int opts;

          opts = fcntl ( m_sockfd,
                 F_GETFL );

          if ( opts < 0 )
            {
              return;
            }

          if ( flag )
            opts = ( opts | O_NONBLOCK );
          else
            opts = ( opts & ~O_NONBLOCK );

          fcntl ( m_sockfd,
              F_SETFL,opts );

    }
}

bool Socket::IsValid() const
{
//if call function socket fail,it returns -1
return m_sockfd!=-1;
}

接下来是异常处理到类

#ifndef SocketException_H
#define SocketException_H

#include <string>

class SocketException
{
public:
SocketException ( std::string description ) : m_description( description ) {};
~SocketException (){};

std::string Description() { return m_description; }

private:
std::string m_description;
};

#endif

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