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C++编写的WebSocket服务端客户端实现示例代码

withpy 2021-10-29

简介本文主要介绍了C++编写的WebSocket服务端客户端实现示例代码,文中通过示例代码介绍的非常详细,具有一定的参考价值,感兴趣的小伙伴们可以参考一下

使用过标准的libwebsockets服务端库测试过,主要是短小精悍,相对于libwebsockets不需要依赖zlib和openssl 以及其他库,直接make就可以使用了,linux跟windows都可以使用。

测试用例:

#include "easywsclient.hpp"
#include <assert.h>
#include <stdio.h>
#include <string>
using easywsclient::WebSocket;
static WebSocket::pointer ws = NULL;
void handle_message(const std::string & message)
{
    printf(">>> %s\n", message.c_str());
    if (message == "world") { ws->close(); }
}
int main()
{
    ws = WebSocket::from_url("ws://localhost:8126/foo");
    assert(ws);//判断ws对象是否为空null
    ws->send("goodbye");
    ws->send("hello");
    //如果你需要多线程,可以在一个thread 维护该ws的连接重连机制
    while (ws->getReadyState() != WebSocket::CLOSED) //判断ws是否正常连接
    {
      ws->poll();//这个必须要调用,否则不能发送,发送跟接收都是异步的,都是在这个poll函数里监测处理的
      ws->dispatch(handle_message);
    }
    delete ws;
    return 0;
}
//线程thread  维护重连连接
void run()
{
    bool conn = FLASE;
    ws = WebSocket::from_url("ws://localhost:8126/foo");
    //如果你需要多线程,可以在一个thread 维护该ws的连接重连机制
    while (1) //判断ws是否正常连接
    {
      if(ws != NULL)
      {
          ws->poll(0);//这个必须要调用,否则不能发送,发送跟接收都是异步的,都是在这个poll函数里监测处    理的
          ws->dispatch(handle_message);
          if(ws->getReadyState() == WebSocket::CLOSED)  
          {
             //ws连接断开 重连
             delete ws;
             ws = NULL;
             ws = WebSocket::from_url("ws://localhost:8126/foo");
          }
          else if(wss->getReadyState()== WebSocket::OPEN)
          {
             //ws连接ok
             //    ws->send("goodbye");
             ws->send("hello");
          }
      }
      else
      {
        ws = WebSocket::from_url("ws://localhost:8126/foo");
        sleep(1);
      }
      usleep(100);
    }
    if(ws!=NULL)
    delete ws;
}

有细心的朋友发现在发送中文GBK 的时候与服务端会断开

//GBK -> UTF-8 
//遇到发送的字符串里有中文的话需要send 前进行转换一下,
//这个是网友提供的在windows下的转换函数
std::string Server_Stream::GBKToUTF8(const std::string& strGBK)
{
 std::string strOutUTF8 = "";
 WCHAR * str1;
 int n = MultiByteToWideChar(CP_ACP, 0, strGBK.c_str(), -1, NULL, 0);
 str1 = new WCHAR[n];
 MultiByteToWideChar(CP_ACP, 0, strGBK.c_str(), -1, str1, n);
 n = WideCharToMultiByte(CP_UTF8, 0, str1, -1, NULL, 0, NULL, NULL);
 char * str2 = new char[n];
 WideCharToMultiByte(CP_UTF8, 0, str1, -1, str2, n, NULL, NULL);
 strOutUTF8 = str2;
 delete[]str1;
 str1 = NULL;
 delete[]str2;
 str2 = NULL;
 return strOutUTF8;
}

下面是C++实现的WebSocket客户端,写好后这里记一下,免得以后忘记。

本示例共有三个文件组成,依赖Websocket++第三方库

其中main.cpp是使用示例

#include <iostream>
#include <string>
#include <sstream>
#include "websocket_endpoint.h"
int main(int argc, char **argv)
{
 bool done = false;
 std::string input;
 kagula::websocket_endpoint endpoint;
 endpoint.connect("ws://localhost:9002");
 while (!done) {
  std::cout << "Enter Command: ";
  std::getline(std::cin, input);
  if (input == "quit") {
   done = true;
  }
  else if (input.substr(0, 4) == "send") {
   std::stringstream ss(input);
   std::string cmd;
   std::string message;
   ss >> cmd;
   std::getline(ss, message);
   endpoint.send(message);
  }
  else if (input.substr(0, 4) == "show") {
   endpoint.show();
  }
  else {
   std::cout << "> Unrecognized Command" << std::endl;
  }
 }
 endpoint.close();
 return 0;
}

其它两个文件是封装

websocket_endpoint.h文件清单

#ifndef _WEBSOCKET_ENDPOINT_
#define _WEBSOCKET_ENDPOINT_
#include <string>
/*
Title: Web Socket Client
Author: kagula
Date: 2016-11-21
Dependencies: Websocket++、Boost::ASIO
Test Environment: VS2013 Update5, WebSocket++ 0.70, Boost 1.61
Description:
[1]Support connect a web socket server.
[2]If server is crash, client will not follow crash.
*/
namespace kagula
{
 class websocket_endpoint {
 public:
  websocket_endpoint();
  ~websocket_endpoint();
  int connect(std::string const & uri);
  void close();
  void send(std::string message);
  void show();
 };
}
#endif

websocket_endpoint.cpp文件清单

#include <websocketpp/config/asio_no_tls_client.hpp>
#include <websocketpp/client.hpp>
#include <websocketpp/common/thread.hpp>
#include <websocketpp/common/memory.hpp>
#include <cstdlib>
#include <iostream>
#include <map>
#include <string>
#include <sstream>
#include "websocket_endpoint.h"
typedef websocketpp::client<websocketpp::config::asio_client> ws_client;
namespace kagula
{
 class connection_metadata {
 public:
  typedef websocketpp::lib::shared_ptr<connection_metadata> ptr;
  connection_metadata(websocketpp::connection_hdl hdl, std::string uri)
   : m_hdl(hdl)
   , m_status("Connecting")
   , m_uri(uri)
   , m_server("N/A")
  {}
  void on_open(ws_client *client, websocketpp::connection_hdl hdl) {
   m_status = "Open";
   ws_client::connection_ptr con = client->get_con_from_hdl(hdl);
   m_server = con->get_response_header("Server");
  }
  // if connection failed, the function will be invoke.
  void on_fail(ws_client *client, websocketpp::connection_hdl hdl) {
   m_status = "Failed";
   ws_client::connection_ptr con = client->get_con_from_hdl(hdl);
   m_server = con->get_response_header("Server");
   m_error_reason = con->get_ec().message();
  }
  void on_close(ws_client *client, websocketpp::connection_hdl hdl) {
   m_status = "Closed";
   ws_client::connection_ptr con = client->get_con_from_hdl(hdl);
   std::stringstream s;
   s << "close code: " << con->get_remote_close_code() << " ("
    << websocketpp::close::status::get_string(con->get_remote_close_code())
    << "), close reason: " << con->get_remote_close_reason();
   m_error_reason = s.str();
  }
  void on_message(websocketpp::connection_hdl, ws_client::message_ptr msg) {
   if (msg->get_opcode() == websocketpp::frame::opcode::text) {
    m_messages.push_back("<< " + msg->get_payload());
   }
   else {
    m_messages.push_back("<< " + websocketpp::utility::to_hex(msg->get_payload()));
   }
  }
  websocketpp::connection_hdl get_hdl() const {
   return m_hdl;
  }
  std::string get_status() const {
   return m_status;
  }
  std::string get_uri() const {
   return m_uri;
  }
  void record_sent_message(std::string message) {
   m_messages.push_back(">> " + message);
  }
  friend std::ostream & operator<< (std::ostream & out, connection_metadata const & data);
 private:
  websocketpp::connection_hdl m_hdl;
  std::string m_status;
  std::string m_uri;
  std::string m_server;
  std::string m_error_reason;
  std::vector<std::string> m_messages;
 };
 std::ostream & operator<< (std::ostream & out, connection_metadata const & data) {
  out << "> URI: " << data.m_uri << "\n"
   << "> Status: " << data.m_status << "\n"
   << "> Remote Server: " << (data.m_server.empty() ? "None Specified" : data.m_server) << "\n"
   << "> Error/close reason: " << (data.m_error_reason.empty() ? "N/A" : data.m_error_reason) << "\n";
  out << "> Messages Processed: (" << data.m_messages.size() << ") \n";
  std::vector<std::string>::const_iterator it;
  for (it = data.m_messages.begin(); it != data.m_messages.end(); ++it) {
   out << *it << "\n";
  }
  return out;
 }
 ws_client g_wsEndPoint;
 connection_metadata::ptr g_wsClientConnection;
 websocketpp::lib::shared_ptr<websocketpp::lib::thread> g_threadWS;
 websocket_endpoint::websocket_endpoint(){
   g_wsEndPoint.clear_access_channels(websocketpp::log::alevel::all);
   g_wsEndPoint.clear_error_channels(websocketpp::log::elevel::all);
   g_wsEndPoint.init_asio();
   g_wsEndPoint.start_perpetual();
   g_threadWS = websocketpp::lib::make_shared<websocketpp::lib::thread>(&ws_client::run, &g_wsEndPoint);
 }
 websocket_endpoint::~websocket_endpoint() {
  g_wsEndPoint.stop_perpetual();
  if (g_wsClientConnection->get_status() == "Open") {
   // Only close open connections
   websocketpp::lib::error_code ec;
   g_wsEndPoint.close(g_wsClientConnection->get_hdl(), websocketpp::close::status::going_away, "", ec);
   if (ec) {
    std::cout << "> Error closing ws connection " << g_wsClientConnection->get_uri() << " :" << ec.message() << std::endl;
   }
  }
  g_threadWS->join();
 }
 int websocket_endpoint::connect(std::string const & uri) {
  websocketpp::lib::error_code ec;
  ws_client::connection_ptr pConnection = g_wsEndPoint.get_connection(uri, ec);
  if (ec) {
   std::cout << "> Connect initialization error: " << ec.message() << std::endl;
   return -1;
  }
  g_wsClientConnection = websocketpp::lib::make_shared<connection_metadata>(pConnection->get_handle(), uri);
  pConnection->set_open_handler(websocketpp::lib::bind(
   &connection_metadata::on_open,
   g_wsClientConnection,
   &g_wsEndPoint,
   websocketpp::lib::placeholders::_1
   ));
  pConnection->set_fail_handler(websocketpp::lib::bind(
   &connection_metadata::on_fail,
   g_wsClientConnection,
   &g_wsEndPoint,
   websocketpp::lib::placeholders::_1
   ));
  pConnection->set_close_handler(websocketpp::lib::bind(
   &connection_metadata::on_close,
   g_wsClientConnection,
   &g_wsEndPoint,
   websocketpp::lib::placeholders::_1
   ));
  pConnection->set_message_handler(websocketpp::lib::bind(
   &connection_metadata::on_message,
   g_wsClientConnection,
   websocketpp::lib::placeholders::_1,
   websocketpp::lib::placeholders::_2
   ));
  g_wsEndPoint.connect(pConnection);
  return 0;
 }
 void close(websocketpp::close::status::value code, std::string reason) {
  websocketpp::lib::error_code ec;
  g_wsEndPoint.close(g_wsClientConnection->get_hdl(), code, reason, ec);
  if (ec) {
   std::cout << "> Error initiating close: " << ec.message() << std::endl;
  }
 }
 void websocket_endpoint::close()
 {
  if (g_wsClientConnection->get_status()=="Open")
  {
   int close_code = websocketpp::close::status::normal;
   kagula::close(close_code, "");
  }
 } 
 void websocket_endpoint::send(std::string message) {
  websocketpp::lib::error_code ec;
  g_wsEndPoint.send(g_wsClientConnection->get_hdl(), message, websocketpp::frame::opcode::text, ec);
  if (ec) {
   std::cout << "> Error sending message: " << ec.message() << std::endl;
   return;
  }
  g_wsClientConnection->record_sent_message(message);
 } 
 void websocket_endpoint::show()
 {
  std::cout << * g_wsClientConnection << std::endl;
 }
}

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