概述
这是两个示例，需要配合使用。可以在本机为两个应用程序建立socket通信。
主要是对QLocalServer和QLocalSocket的使用。
QLocalServer
- 调用 listen(),让服务器开始监听本地套接字上指定关键字的连接。
- 每次客户端连接到服务器时，都会发出newConnection()信号。
- 调用nextPendingConnection（）将挂起的连接接受为已连接的QLocalSocket。该函数返回一个指向QLocalSocket的指针，用于与客户端通信。
QLocalSocket
建立连接后，通过套接字收发数据。
Server 程序
Server 类定义
#ifndef SERVER_H
#define SERVER_H
#include <QDialog>
QT_BEGIN_NAMESPACE
class QLabel;
class QPushButton;
class QLocalServer;
QT_END_NAMESPACE
class Server : public QDialog
{
Q_OBJECT
public:
explicit Server(QWidget *parent = nullptr);
private slots:
void sendFortune();
private:
//QLocalServer接受传入的本地套接字连接。
QLocalServer *server;
///抽取的签筒,里面放了各种签
QStringList fortunes;
};
#endif
Server类实现
#include "server.h"
#include <QtWidgets>
#include <QtNetwork>
Server::Server(QWidget *parent)
: QDialog(parent)
{
setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
server = new QLocalServer(this);
//调用 listen（）让服务器开始监听指定关键字（fortune）上的传入连接。
if (!server->listen("fortune")) {
QMessageBox::critical(this, tr("Local Fortune Server"),
tr("Unable to start the server: %1.")
.arg(server->errorString()));
close();
return;
}
QLabel *statusLabel = new QLabel;
statusLabel->setWordWrap(true);
statusLabel->setText(tr("The server is running.\n"
"Run the Local Fortune Client example now."));
//把各种签放入，签筒
fortunes << tr("You've been leading a dog's life. Stay off the furniture.")
<< tr("You've got to think about tomorrow.")
<< tr("You will be surprised by a loud noise.")
<< tr("You will feel hungry again in another hour.")
<< tr("You might have mail.")
<< tr("You cannot kill time without injuring eternity.")
<< tr("Computers are not intelligent. They only think they are.");
QPushButton *quitButton = new QPushButton(tr("Quit"));
//自动默认按钮 设置为false
quitButton->setAutoDefault(false);
connect(quitButton, &QPushButton::clicked, this, &Server::close);
//每次客户端连接到服务器时，都会发出newConnection（）信号。
connect(server, &QLocalServer::newConnection, this, &Server::sendFortune);
QHBoxLayout *buttonLayout = new QHBoxLayout;
//一共三格，button在中间，两边为空。
buttonLayout->addStretch(1);
buttonLayout->addWidget(quitButton);
buttonLayout->addStretch(1);
QVBoxLayout *mainLayout = new QVBoxLayout(this);
mainLayout->addWidget(statusLabel);
mainLayout->addLayout(buttonLayout);
setWindowTitle(QGuiApplication::applicationDisplayName());
}
void Server::sendFortune()
{
//const char *的高级版。
//支持隐式共享 (copy-on-write)
//确保以 '\0'结尾
QByteArray block;
//构造一个操作字节数组的数据流，
QDataStream out(&block, QIODevice::WriteOnly);
//如果与使用的QT版本相同可以不设置。
out.setVersion(QDataStream::Qt_5_10);
const int fortuneIndex = QRandomGenerator::global()->bounded(0, fortunes.size());
const QString &message = fortunes.at(fortuneIndex);
out << quint32(message.size());
out << message;
//调用nextPendingConnection（）将挂起的连接接受为已连接的QLocalSocket。
//该函数返回一个指向QLocalSocket的指针，用于与客户端通信。
QLocalSocket *clientConnection = server->nextPendingConnection();
//回收内存
connect(clientConnection, &QLocalSocket::disconnected,
clientConnection, &QLocalSocket::deleteLater);
//block的数据与来自out数据流
//将数据从以零结尾的8位字符字符串写入QLocalSocket缓冲。
clientConnection->write(block);
//QLocalSocket立即开始发送缓冲数据。
clientConnection->flush();
clientConnection->disconnectFromServer();
}
服务器main函数
#include <QApplication>
#include "server.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
//后面写成QApplication::tr("Local Fortune Server")也行。
//QObject::tr，纯粹是为了加入翻译文件
QGuiApplication::setApplicationDisplayName(Server::tr("Local Fortune Server"));
Server server;
server.show();
return app.exec();
}
Clint 程序
Clint类定义
#ifndef CLIENT_H
#define CLIENT_H
#include <QDialog>
#include <QDataStream>
#include <QLocalSocket>
QT_BEGIN_NAMESPACE
class QLabel;
class QLineEdit;
class QPushButton;
QT_END_NAMESPACE
class Client : public QDialog
{
Q_OBJECT
public:
explicit Client(QWidget *parent = nullptr);
private slots:
void requestNewFortune();
void readFortune();
void displayError(QLocalSocket::LocalSocketError socketError);
void enableGetFortuneButton();
private:
QLineEdit *hostLineEdit;
QPushButton *getFortuneButton;
QLabel *statusLabel;
QLocalSocket *socket;
//接收socket中的数据
//正常接收情况下in包括：blockSize和nextFortune
QDataStream in;
//服务器发来的“签”的文字长度
quint32 blockSize;
QString currentFortune;
};
#endif
Clint类实现
#include <QtWidgets>
#include <QtNetwork>
#include "client.h"
Client::Client(QWidget *parent)
: QDialog(parent),
hostLineEdit(new QLineEdit("fortune")),
getFortuneButton(new QPushButton(tr("Get Fortune"))),
statusLabel(new QLabel(tr("This examples requires that you run the "
"Local Fortune Server example as well."))),
socket(new QLocalSocket(this))
{
setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
QLabel *hostLabel = new QLabel(tr("&Server name:"));
hostLabel->setBuddy(hostLineEdit);
statusLabel->setWordWrap(true);
getFortuneButton->setDefault(true);
QPushButton *quitButton = new QPushButton(tr("Quit"));
QDialogButtonBox *buttonBox = new QDialogButtonBox;
buttonBox->addButton(getFortuneButton, QDialogButtonBox::ActionRole);
buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);
//从socket获取数据流
in.setDevice(socket);
in.setVersion(QDataStream::Qt_5_10);
//本示例中下面这个connect可以忽略
connect(hostLineEdit, &QLineEdit::textChanged,
this, &Client::enableGetFortuneButton);
connect(getFortuneButton, &QPushButton::clicked,
this, &Client::requestNewFortune);
connect(quitButton, &QPushButton::clicked, this, &Client::close);
//每当有新的数据可从设备当前的读取通道读取时，就会发出一次readyRead信号。
connect(socket, &QLocalSocket::readyRead, this, &Client::readFortune);
connect(socket, QOverload<QLocalSocket::LocalSocketError>::of(&QLocalSocket::error),
this, &Client::displayError);
QGridLayout *mainLayout = new QGridLayout(this);
mainLayout->addWidget(hostLabel, 0, 0);
mainLayout->addWidget(hostLineEdit, 0, 1);
mainLayout->addWidget(statusLabel, 2, 0, 1, 2);
mainLayout->addWidget(buttonBox, 3, 0, 1, 2);
setWindowTitle(QGuiApplication::applicationDisplayName());
hostLineEdit->setFocus();
}
void Client::requestNewFortune()
{
// 本示例中，下条语句可以忽略
getFortuneButton->setEnabled(false);
//初始化为0
blockSize = 0;
//立即中止当前连接并重置套接字。
socket->abort();
//通过指定的关键字与Server建立连接
socket->connectToServer(hostLineEdit->text());
}
void Client::readFortune()
{
//为blockSize赋值
if (blockSize == 0) {
// QDataStream将一个quint32序列化为sizeof（quint32）个字节
// bytesAvailable返回可供读取的字节数。
// 目前我们需要读取的blockSize，类型为quint32
if (socket->bytesAvailable() < (int)sizeof(quint32))
return;
//从socket读取quint32,socket->bytesAvailable() 的值会相应的减少。
in >> blockSize;
}
if (socket->bytesAvailable() < blockSize || in.atEnd())
return;
QString nextFortune;
//从socket读取字符串,socket->bytesAvailable() 的值会相应的减少。
in >> nextFortune;
//确保这次抽到的签与上次不同
if (nextFortune == currentFortune) {
//在给定的时间间隔后调用插槽,非常方便的静态函数
QTimer::singleShot(0, this, &Client::requestNewFortune);
return;
}
currentFortune = nextFortune;
statusLabel->setText(currentFortune);
getFortuneButton->setEnabled(true);
}
void Client::displayError(QLocalSocket::LocalSocketError socketError)
{
switch (socketError) {
case QLocalSocket::ServerNotFoundError:
QMessageBox::information(this, tr("Local Fortune Client"),
tr("The host was not found. Please make sure "
"that the server is running and that the "
"server name is correct."));
break;
case QLocalSocket::ConnectionRefusedError:
QMessageBox::information(this, tr("Local Fortune Client"),
tr("The connection was refused by the peer. "
"Make sure the fortune server is running, "
"and check that the server name "
"is correct."));
break;
case QLocalSocket::PeerClosedError:
break;
default:
QMessageBox::information(this, tr("Local Fortune Client"),
tr("The following error occurred: %1.")
.arg(socket->errorString()));
}
getFortuneButton->setEnabled(true);
}
void Client::enableGetFortuneButton()
{
getFortuneButton->setEnabled(!hostLineEdit->text().isEmpty());
}
客户端 main 函数
#include <QApplication>
#include "client.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QGuiApplication::setApplicationDisplayName(Client::tr("Local Fortune Client"));
Client client;
client.show();
return app.exec();
}
![QT5.14.2自带Examples：Draggable Icons[图]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)