QLocalSocket

https://www.cnblogs.com/xiangtingshen/p/11063583.html

https://blog.csdn.net/u011546766/article/details/86516339

https://blog.csdn.net/yhc166188/article/details/80756448

QIODevice做为QLocalSocket的父类

在Qt中，提供了多种IPC方法。看起来好像和Socket搭上点边，实则底层是windows的name pipe。这应该是支持双工通信的

QLocalServer提供了一种基于本地套接字的服务器，实现了接收本地socket的连接的功能。

通过调用listen()监听特定的连接，每次与client连接上时发出newConnection()信号。

通过调用nextPendingConnection()响应一个等待中的连接请求，返回一个指针，指向用于与client建立通信的QLocalSocket。

当连接发生错误时，serverError() 返回错误的类型，通过调用errorString()可以获取错误描述。

监听过程中，serverName()可获取当前服务器的名称。

调用close()停止对连接请求的监听。

虽然QLocalServer是为在事件循环中使用而设计出来的，但是在没有事件循环时也是可以使用的。

没有事件循环时，你必须使用waitForNewConnection()，它只在以下两种情况下解除阻塞：1）有可用的连接；2）超时。

服务器

#ifndef SERVER_H
#define SERVER_H

#include <QWidget>
#include <QObject>
#include <QLocalSocket>
#include <QLocalServer>

class CServer : public QObject
{
Q_OBJECT

public:
CServer() : m_server(NULL)
{
m_server = new QLocalServer;
connect(m_server, SIGNAL(newConnection()), SLOT(serverNewConnectionHandler()));
}

~CServer()
{
m_server->close();
delete m_server;
}

void RunServer()
{
qDebug() << "Run Server ok";

QLocalServer::removeServer("ServerName");
bool ok = m_server->listen("ServerName");
if (!ok)
{
// TODO:
}
}

private slots:
void serverNewConnectionHandler()
{
qDebug() << "New Connection";
qDebug() << "listen: " << m_server->serverName();

QLocalSocket* socket = m_server->nextPendingConnection();
connect(socket, SIGNAL(readyRead()), this, SLOT(socketReadyReadHandler()));
connect(socket, SIGNAL(disconnected()), socket, SLOT(deleteLater()));
}

void socketReadyReadHandler()
{
QLocalSocket* socket = static_cast<QLocalSocket*>(sender());
if (socket)
{
QTextStream stream(socket);
qDebug() << "Read Data From Client:" << stream.readAll();

QString response = "Hello Client";
socket->write(response.toUtf8());
socket->flush();
}
// 返回到客户端的void sendMessage 方法，m_socket->waitForReadyRead()之后的操作
}

private:
QLocalServer *m_server;

};

#endif // SERVER_H

#include "server.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

CServer server;
server.RunServer();

return a.exec();
}

客户端

#ifndef CLIENT_H
#define CLIENT_H

#include <QObject>
#include <QLocalSocket>
#include <QLocalServer>

class CClient : public QObject
{
Q_OBJECT

public:
CClient() : m_socket(NULL)
{
m_socket = new QLocalSocket();

connect(m_socket, SIGNAL(connected()), SLOT(socketConnectedHandler()));
connect(m_socket, SIGNAL(disconnected()), SLOT(socketDisConnectedHandler()));
connect(m_socket, SIGNAL(error(QLocalSocket::LocalSocketError)), SLOT(socketErrorHandler(QLocalSocket::LocalSocketError)));
}

~CClient()
{
m_socket->disconnectFromServer();
delete m_socket;
}

public:
void ConnectToServer(const QString &strServerName)
{
// serverNewConnectionHandler 成员方法将被调用
m_socket->connectToServer(strServerName);
if (m_socket->waitForConnected())
{
// TODO:
}
}

void sendMessage(const QString &msg)
{
m_socket->write(msg.toStdString().c_str());
m_socket->flush();

if (!m_socket->bytesAvailable())
m_socket->waitForReadyRead();

QTextStream stream(m_socket);
QString respond = stream.readAll();
qDebug() << "Read Data From Server:" << respond;
}

private slots:
void socketConnectedHandler()
{
qDebug() << "connected.";
}

void socketDisConnectedHandler()
{
qDebug() << "disconnected.";
}

void socketErrorHandler(QLocalSocket::LocalSocketError error)
{
qWarning() << error;
}

private:
QLocalSocket *m_socket;

};

#endif // CLIENT_H

#include "client.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

CClient client;
client.ConnectToServer("ServerName");

client.sendMessage("Hellow Server");

return a.exec();
}

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