c++ - boost::asio 文件发送

Question

有一个服务器通过 http 响应 .png 文件:

#include "server.h"
string Server::header(int contentLength)
{
    string h =
    "HTTP/1.1 200 OK\n"
    "Content-Length: " + boost::lexical_cast<string>(contentLength) + "\n"
    "Content-Type: image/png;\n"
    "Connection: close\n"
    "\n";
    return h;
}
string Server::readMap(const string &filename)
{
    ifstream file (filename.c_str(), ios::in|ios::binary);
    string reply;
    char buf[512];
    while (file.read(buf, sizeof(buf)).gcount() > 0)
        reply.append(buf, file.gcount());
    return reply;
}
void Server::run(const string &filename, int port)
{
    string data = readMap(filename);
    try
    {
        boost::asio::io_service io_service;
        tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), port));
        for (;;)
        {
          tcp::socket socket(io_service);
          acceptor.accept(socket);
          boost::asio::write(socket, boost::asio::buffer(header( data.size() )));
          boost::asio::write(socket, boost::asio::buffer(data));
        }
    }
    catch (std::exception& e)
    {
        cerr << "exception: " << e.what() << endl;
    }
}

每次发生错误时:

exception: Connection reset by peer

我可以在我的浏览器中看到图像的某些部分，有时图像几乎是完整的，但它永远不会在没有错误的情况下工作。

如果我使用 wget 看起来像

wget http://localhost:8089
--2012-03-07 12:07:19--  http://localhost:8089/
Resolving localhost... 127.0.0.1
Connecting to localhost|127.0.0.1|:8089... connected.
HTTP request sent, awaiting response... 200 OK
Length: 760032 (742K) [image/png]
Saving to: `index.html'

62% [========================================================>                                   ] 475,136     --.-K/s   in 0.002s  

2012-03-07 12:07:19 (287 MB/s) - Read error at byte 475136/760032 (Connection reset by peer). Retrying.

--2012-03-07 12:07:20--  (try: 2)  http://localhost:8089/
Connecting to localhost|127.0.0.1|:8089... connected.
HTTP request sent, awaiting response... 200 OK
Length: 760032 (742K) [image/png]
Saving to: `index.html'

73% [==================================================================>                         ] 557,056     --.-K/s   in 0.001s  

... many failes and finally

--2012-03-07 12:09:01--  (try: 9)  http://localhost:8089/
Connecting to localhost|127.0.0.1|:8089... connected.
HTTP request sent, awaiting response... 200 OK
Length: 760032 (742K) [image/png]
Saving to: `index.html'

100%[===========================================================================================>] 760,032     --.-K/s   in 0.001s 

有什么解决办法吗？

Answer 1

ASIO 文档中有几个更完整的 HTTP 实现，包括静态文件服务。一种方法是为您的应用程序重用部分示例代码。

在这种特殊情况下，在 http://www.boost.org/doc/libs/1_49_0/doc/html/boost_asio/example/http/server/request_handler.cpp 处有一个如何正确打开和缓冲文件的示例

  std::ifstream is(full_path.c_str(), std::ios::in | std::ios::binary);
    ...
  char buf[512];
  while (is.read(buf, sizeof(buf)).gcount() > 0)
    rep.content.append(buf, is.gcount());

该文档还有实际异步 HTTP 实现的示例。 (我假设您正在使用 boost::asio 最终使其异步？)