asio套接字，在分隔符处拆分传入数据？

Question

我正在从 c++ 中的 asio 套接字读取数据。

我需要将传入的数据解析为 json。为此，我需要获取单个 json 字符串条目。我正在添加一个字符';'在 json 字符串的末尾，现在我需要在读取时拆分该字符。我正在尝试这个：

int main()
{
    asio::io_service service;
    asio::ip::tcp::endpoint endpoint(asio::ip::address::from_string("127.0.0.1"), 4444);
    asio::ip::tcp::socket socket(service);
    std::cout << "[Client] Connecting to server..." << std::endl;
    socket.connect(endpoint);
    std::cout << "[Client] Connection successful" << std::endl;


    while (true)
    {

        std::string str;
        str.resize(2048);
        asio::read(socket, asio::buffer(str));

        std::string parsed;
        std::stringstream input_stringstream(str);


        if (std::getline(input_stringstream, parsed, ';'))
        {
                            
            std::cout << parsed << std::endl;
            std::cout<<std::endl;
        }

    

    }
}

但它给了我字符串的随机部分。

完整的信息是：（用于测试，不是json格式）

this is the message in full, no more no less ;

我得到：

 full, no more no less

this is the message in full, no more no less

ull, no more no less

is is the message in full, no more no less

l, no more no less

 is the message in full, no more no less

 no more no less

我哪里错了？

谢谢！

Answer 1

我会使用read_until:

#include <boost/asio.hpp>
#include <iostream>
#include <iomanip>
namespace asio = boost::asio;
using asio::ip::tcp;

int main()
{
    asio::io_service service;
    tcp::socket      socket(service);
    socket.connect({{}, 4444});

    std::string str;
    while (auto n = asio::read_until(socket, asio::dynamic_buffer(str), ';')) {
        std::cout << std::quoted(std::string_view(str).substr(0, n - 1)) << std::endl;
        str.erase(0, n);
    }
}

以示例服务器为例：

paste -sd\; /etc/dictionaries-common/words  | netcat -l -p 4444

输出是：

"A"
"A's"
"AMD"
"AMD's"
"AOL"
"AOL's"
"Aachen"
"Aachen's"
"Aaliyah"
"Aaliyah's"
"Aaron"
"Aaron's"
"Abbas"
"Abbas's"
"Aberdeen's"
...
"zucchinis"
"zwieback"
"zwieback's"
"zygote"
"zygote's"
"zygotes"
"Ångström"
"Ångström's"
"éclair"
"éclair's"
"éclairs"
"éclat"
"éclat's"
"élan"
"élan's"
"émigré"
"émigré's"
"émigrés"
"épée"
"épée's"
"épées"
"étude"
"étude's"

其他提示

您可以使用任何动态缓冲区。这里是streambuf：

for (asio::streambuf buf; auto n = asio::read_until(socket, buf, ';');) {
    std::cout << std::string_view(
                     asio::buffer_cast<char const*>(buf.data()), n)
              << std::endl;
    buf.consume(n);
}

或者，混合，表明dynamic_string_buffer 与streambuf 建模相同的概念：

std::string str;
for (auto buf = asio::dynamic_buffer(str);
     auto n   = asio::read_until(socket, buf, ';');) {
    std::cout << std::string_view(
                     asio::buffer_cast<char const*>(buf.data()), n)
              << std::endl;
    buf.consume(n);
}

也可以：

std::vector<unsigned char> vec;
for (auto buf = asio::dynamic_buffer(vec);
     auto n   = asio::read_until(socket, buf, ';');) {
    std::cout << std::string_view(
                     asio::buffer_cast<char const*>(buf.data()), n)
              << std::endl;
    buf.consume(n);
}