这是我的代码:

// Not all headers are relevant to the code snippet.
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <cstdlib>
#include <cstring>
#include <unistd.h>

char *buffer;
stringstream readStream;
bool readData = true;

while (readData)
{
    cout << "Receiving chunk... ";

    // Read a bit at a time, eventually "end" string will be received.
    bzero(buffer, BUFFER_SIZE);
    int readResult = read(socketFileDescriptor, buffer, BUFFER_SIZE);
    if (readResult < 0)
    {
        THROW_VIMRID_EX("Could not read from socket.");
    }

    // Concatenate the received data to the existing data.
    readStream << buffer;

    // Continue reading while end is not found.
    readData = readStream.str().find("end;") == string::npos;

    cout << "Done (length: " << readStream.str().length() << ")" << endl;
}

如您所知，它有点像 C 和 C++。 BUFFER_SIZE 是 256 - 我应该增加大小吗？如果是这样，该怎么办？有关系吗？

我知道如果出于某种原因没有收到“end”，这将是一个无限循环，这很糟糕 - 所以如果你能提出更好的方法，也请这样做。

最佳答案

在不了解您的完整应用程序的情况下，很难说解决问题的最佳方法是什么，但一种常见的技术是使用以固定长度字段开头的 header ，该字段表示消息其余部分的长度.

假设您的 header 仅包含一个 4 字节整数，表示您的消息其余部分的长度。然后只需执行以下操作。

// This assumes buffer is at least x bytes long,
// and that the socket is blocking.
void ReadXBytes(int socket, unsigned int x, void* buffer)
{
    int bytesRead = 0;
    int result;
    while (bytesRead < x)
    {
        result = read(socket, buffer + bytesRead, x - bytesRead);
        if (result < 1 )
        {
            // Throw your error.
        }

        bytesRead += result;
    }
}

然后在后面的代码中

unsigned int length = 0;
char* buffer = 0;
// we assume that sizeof(length) will return 4 here.
ReadXBytes(socketFileDescriptor, sizeof(length), (void*)(&length));
buffer = new char[length];
ReadXBytes(socketFileDescriptor, length, (void*)buffer);

// Then process the data as needed.

delete [] buffer;

这做了一些假设:

• 发送方和接收方的整数大小相同。
• 发送方和接收方的字节序相同。
• 您可以控制双方的协议(protocol)
• 发送消息时，您可以预先计算长度。

由于通常希望明确知道您通过网络发送的整数的大小，因此在头文件中定义它们并明确使用它们，例如:

// These typedefs will vary across different platforms
// such as linux, win32, OS/X etc, but the idea
// is that a Int8 is always 8 bits, and a UInt32 is always
// 32 bits regardless of the platform you are on.
// These vary from compiler to compiler, so you have to 
// look them up in the compiler documentation.
typedef char Int8;
typedef short int Int16;
typedef int Int32;

typedef unsigned char UInt8;
typedef unsigned short int UInt16;
typedef unsigned int UInt32;

这会将上面的内容更改为:

UInt32 length = 0;
char* buffer = 0;

ReadXBytes(socketFileDescriptor, sizeof(length), (void*)(&length));
buffer = new char[length];
ReadXBytes(socketFileDescriptor, length, (void*)buffer);

// process

delete [] buffer;

我希望这会有所帮助。

https://stackoverflow.com/questions/666601/