Poco C++庫網絡模塊例子解析2-------HttpServer

時間 2019-11-13
標籤 poco c++ 網絡模塊例子解析 httpserver 欄目 C&C++ 简体版
原文原文鏈接
//下面程序取自 Poco 庫的Net模塊例子----HTTPServer  下面開始解析代碼


#include "Poco/Net/HTTPServer.h"   //繼承自TCPServer 實現了一個完整的HTTP多線程服務器
#include "Poco/Net/HTTPRequestHandler.h"   //抽象基類類 被HttpServer所建立 用來處理Http的請求
#include "Poco/Net/HTTPRequestHandlerFactory.h" //HTTPRequestHandler的工廠 給予工廠設計模式 
#include "Poco/Net/HTTPServerParams.h"    //被用來指定httpserver以及HTTPRequestHandler的參數
#include "Poco/Net/HTTPServerRequest.h"  //ServerRequest的抽象子類用來指定 服務器端的 http請求
#include "Poco/Net/HTTPServerResponse.h" //ServerResponse的抽象子類用來指定服務器端的http響應
#include "Poco/Net/ServerSocket.h"  //提供了一個TCP服務器套接字接口
#include "Poco/Net/WebSocket.h"  //這個類實現了RFC 6455 web套接字接口  專門針對web服務器用
#include "Poco/Net/NetException.h"  //網絡異常
#include "Poco/Util/ServerApplication.h" //Application的子類 全部服務器程序 包括 Reactor FTP HTTP等都用到 算是服務器的啓動類 
#include "Poco/Util/Option.h"  //存儲了命令行選項
#include "Poco/Util/OptionSet.h"  //一個Opention對象的集合
#include "Poco/Util/HelpFormatter.h" //從OptionSet格式化幫助信息
#include "Poco/Format.h"  //格式化函數的實現相似於 C的 sprintf函數 具體看文檔
#include <iostream>


using Poco::Net::ServerSocket;
using Poco::Net::WebSocket;
using Poco::Net::WebSocketException;
using Poco::Net::HTTPRequestHandler;
using Poco::Net::HTTPRequestHandlerFactory;
using Poco::Net::HTTPServer;
using Poco::Net::HTTPServerRequest;
using Poco::Net::HTTPResponse;
using Poco::Net::HTTPServerResponse;
using Poco::Net::HTTPServerParams;
using Poco::Timestamp;
using Poco::ThreadPool;
using Poco::Util::ServerApplication;
using Poco::Util::Application;
using Poco::Util::Option;
using Poco::Util::OptionSet;
using Poco::Util::HelpFormatter;

//////頁面處理器 連接到來的時候 直接打印html內容
class PageRequestHandler: public HTTPRequestHandler
    /// Return a HTML document with some JavaScript creating
    /// a WebSocket connection.
{
public:
    void handleRequest(HTTPServerRequest& request, HTTPServerResponse& response)
    {
         
        response.setChunkedTransferEncoding(true);
        response.setContentType("text/html");
        std::ostream& ostr = response.send();
        ostr << "<html>";
        ostr << "<head>";
        ostr << "<title>WebSocketServer</title>";
        ostr << "<script type=\"text/javascript\">";
        ostr << "function WebSocketTest()";
        ostr << "{";
        ostr << "  if (\"WebSocket\" in window)";
        ostr << "  {";
        ostr << "    var ws = new WebSocket(\"ws://" << request.serverAddress().toString() << "/ws\");";
        ostr << "    ws.onopen = function()";
        ostr << "      {";
        ostr << "        ws.send(\"Hello, world!\");";
        ostr << "      };";
        ostr << "    ws.onmessage = function(evt)";
        ostr << "      { ";
        ostr << "        var msg = evt.data;";
        ostr << "        alert(\"Message received: \" + msg);";
        ostr << "        ws.close();";
        ostr << "      };";
        ostr << "    ws.onclose = function()";
        ostr << "      { ";
        ostr << "        alert(\"WebSocket closed.\");";
        ostr << "      };";
        ostr << "  }";
        ostr << "  else";
        ostr << "  {";
        ostr << "     alert(\"This browser does not support WebSockets.\");";
        ostr << "  }";
        ostr << "}";
        ostr << "</script>";
        ostr << "</head>";
        ostr << "<body>";
        ostr << "  <h1>WebSocket Server</h1>";
        ostr << "  <p><a href=\"javascript:WebSocketTest()\">Run WebSocket Script</a></p>";
        ostr << "</body>";
        ostr << "</html>";
    }
};

/////////http請求處理器 1
class WebSocketRequestHandler: public HTTPRequestHandler
    /// Handle a WebSocket connection.
{
public:
    void handleRequest(HTTPServerRequest& request, HTTPServerResponse& response)
    {
        Application& app = Application::instance();
        try
        {
            WebSocket ws(request, response);
            app.logger().information("WebSocket connection established.");
            char buffer[1024];
            int flags;
            int n;
            do
            {
                n = ws.receiveFrame(buffer, sizeof(buffer), flags);
                app.logger().information(Poco::format("Frame received (length=%d, flags=0x%x).", n, unsigned(flags)));
                ws.sendFrame(buffer, n, flags);
            }
            while (n > 0 || (flags & WebSocket::FRAME_OP_BITMASK) != WebSocket::FRAME_OP_CLOSE);
            app.logger().information("WebSocket connection closed.");
        }
        catch (WebSocketException& exc)
        {
            app.logger().log(exc);
            switch (exc.code())
            {
            case WebSocket::WS_ERR_HANDSHAKE_UNSUPPORTED_VERSION:
                response.set("Sec-WebSocket-Version", WebSocket::WEBSOCKET_VERSION);
                // fallthrough
            case WebSocket::WS_ERR_NO_HANDSHAKE:
            case WebSocket::WS_ERR_HANDSHAKE_NO_VERSION:
            case WebSocket::WS_ERR_HANDSHAKE_NO_KEY:
                response.setStatusAndReason(HTTPResponse::HTTP_BAD_REQUEST);
                response.setContentLength(0);
                response.send();
                break;
            }
        }
    }
};

//HTTP請求處理器工廠 
class RequestHandlerFactory: public HTTPRequestHandlerFactory
{
public:
    HTTPRequestHandler* createRequestHandler(const HTTPServerRequest& request) //覆蓋方法 
    {
        Application& app = Application::instance();  
        app.logger().information("Request from " 
            + request.clientAddress().toString()
            + ": "
            + request.getMethod()
            + " "
            + request.getURI()
            + " "
            + request.getVersion());
            
//打印全部連接請求
        for (HTTPServerRequest::ConstIterator it = request.begin(); it != request.end(); ++it)
        {
            app.logger().information(it->first + ": " + it->second);
        }
        //能夠選擇輸出html頁面 或者不輸出  經過http請求參數
        if(request.find("Upgrade") != request.end() && request["Upgrade"] == "websocket")
            return new WebSocketRequestHandler;
        else
            return new PageRequestHandler;
    }
};


//////////網絡應用程序的啓動器 都是ServerApplication
class WebSocketServer: public Poco::Util::ServerApplication
{
public:
    WebSocketServer(): _helpRequested(false)
    {
    }
    
    ~WebSocketServer()
    {
    }

protected:
    ///再啓動的時候先調用
    void initialize(Application& self)
    {
        loadConfiguration(); // load default configuration files, if present
        ServerApplication::initialize(self);
    }
    //在釋放的時候調用    
    void uninitialize()
    {
        ServerApplication::uninitialize();
    }
   
   ///覆蓋基類的函數 定義一些命令選項
    void defineOptions(OptionSet& options)
    {
        ServerApplication::defineOptions(options);
        
        options.addOption(
            Option("help", "h", "display help information on command line arguments")
                .required(false)
                .repeatable(false));
    }
   ///處理命令行選項 
    void handleOption(const std::string& name, const std::string& value)
    {
        ServerApplication::handleOption(name, value);

        if (name == "help")
            _helpRequested = true;
    }
  
  //打印幫助
    void displayHelp()
    {
        HelpFormatter helpFormatter(options());
        helpFormatter.setCommand(commandName());
        helpFormatter.setUsage("OPTIONS");
        helpFormatter.setHeader("A sample HTTP server supporting the WebSocket protocol.");
        helpFormatter.format(std::cout);
    }
    //在初始化完畢以後調用
    int main(const std::vector<std::string>& args)
    {
        if (_helpRequested)
        {
            displayHelp();
        }
        else
        {
            // get parameters from configuration file
            //從配置文件中獲取端口
            unsigned short port = (unsigned short) config().getInt("WebSocketServer.port", 9980);
            
            // 安裝一個ServerSocket
            ServerSocket svs(port);
            // s安裝一個HttpServer實例  而且傳遞 請求處理器工廠  和一個HttpServerParams對象
            HTTPServer srv(new RequestHandlerFactory, svs, new HTTPServerParams);
            // 啓動服務器
            srv.start();
            // 等待kill 或者控制檯CTRL+C
            waitForTerminationRequest();
            // 中止HTTP服務器
            srv.stop();
        }
        return Application::EXIT_OK;  //返回正常退出狀態
    }
    
private:
    bool _helpRequested;
};

//啓動web 服務器
POCO_SERVER_MAIN(WebSocketServer)