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。
实例1：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();
}
QLocalSocket继承自QIODevice，提供了一种本地套接字，在Windows系统中其实是一种有名管道，在Unix中是一种本地套接字。
socketError()返回套接字连接错误类型，errorString()返回错误详细描述。
也可以在没有事件循环的情况下工作，waitForConnected(),waitForReadyRead(),waitForBytesWritten()和waitForDisconnected()用于阻塞等待事件的到来，知道事件到来或者超时。
实例2：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();
}
