很多情形下，我们在应用程序的最外层都使用TCP作为可靠控制，下面，我就总结一下我在项目中使用QTcpServer与QTcpSocket的一些心得和体会。
服务端TCP程序可以利用QTcpServer，首先我们声名QTcpServer *对象(注意：QTcpServer占用的网络资源需要我们手动释放，任何我们程序可能异常退出或正常结束的地方QTcpServer *最后都要close())
注意我们的服务端要一直监听客户端
tcpPort=8888;
tcpServer=new QTcpServer();
if(!tcpServer->listen(QHostAddress::Any,tcpPort))
{
tcpServer->close();
emit MSG(QString("listen erro"));
}
connect(tcpServer,&QTcpServer::newConnection,this,&TcpServer::onNewConnection);
在新连接对应的槽里我们把
QTcpSocket *newpeer=tcpServer->nextPendingConnection();
这个新连接的socket指针取下来，进行操作，当执行newpeer->write(QByterArray &MSG)即服务器向此peer发送数据；当执行QByterArray MSG=newpeer->write()即服务器读此peer的数据，所有信息的传递均是对QTcpSocket的操作,并要要对每一个socket的disconnected连接deleteLater槽防止内存泄漏。
说到此处，就牵涉到了QString 与QByterArray的转换，因为我们平时处理消息大多是对QSring进行处理：
QString->QByterArray(只有英文(Latin)时)：
newpeer->write(QString("Server").toLatin1());
QByterArray-> QString:
QTextCodec *tc= QTextCodec::codecForName("UTF-8");
QString str=tc->toUnicode((QByteArray)
rawreply)
下面的代码抽取自 我的服务端程序
#ifndef TCPSERVER_H
#define TCPSERVER_H
#include
#include
#include
class TcpServer : public QObject
{
Q_OBJECT
public:
explicit TcpServer(QObject *parent = 0);
~TcpServer();
private:
int nb_peer;//总共的小伙伴数目，用于确定client->index的取值
QTcpServer *tcpServer;
public slots:
void ReadDataFromSocket();
void onNewConnection();
void onDisConnection();
void processMSG(QString &MSG);
// void processAddedClient(QTcpSocket *client);
};
#include "tcpserver.h"
TcpServer::TcpServer(QObject *parent) :
QObject(parent),nb_peer(0)
{
tcpPort=8888;
tcpServer=new QTcpServer();
if(!tcpServer->listen(QHostAddress::Any,tcpPort))
{
tcpServer->close();
emit MSG(QString("listen erro"));
}
peerList = QList();
connect(tcpServer,&QTcpServer::newConnection,this,&TcpServer::onNewConnection);
}
void TcpServer::onNewConnection()
{
QTcpSocket *newpeer=tcpServer->nextPendingConnection();
//写入验证
connect(newpeer,SIGNAL(readyRead()),this,SLOT(ReadDataFromSocket()));
connect(newpeer,SIGNAL(disconnected()),newpeer,SLOT(deleteLater()));
connect(newpeer,SIGNAL(disconnected()),this,SLOT(onDisConnection()));
newpeer->write(QString("Server").toLatin1());
newpeer->flush();
}
#include
#include
void TcpServer::ReadDataFromSocket()
{
QByteArray rawreply= static_cast(sender())->readAll();
QTextCodec *tc= QTextCodec::codecForName("UTF-8");
client beingCheckedClient;
beingCheckedClient.index=nb_peer;
beingCheckedClient.socket=static_cast(sender());
if(tc->toUnicode(rawreply)!=QString("Client")&& !peerList.contains(beingCheckedClient
))
{
//写入信息
//emit ChangeLabel(QString(rawreply));
static_cast(sender())->write(
QString("connect time out! disconnecting...").toLatin1());
static_cast(sender())->flush();
static_cast(sender())->disconnectFromHost();
return ;
}
}
TcpServer::~TcpServer()
{
tcpServer->close();
}
客户端就没什么好说的了，也是对QTcpSocket的一些操作，但是注意要在程序开始时对服务器发起连接：
tcpsocket=new QTcpSocket();
tcpsocket->abort();
tcpsocket->connectToHost(("127.0.0.1"),8888);
一些问题：很多大牛可能会说，我直接使用write read接受字符串命令可能并不安全，在实际应用中我发现，低频率的收发数据这种方法非常可靠，但是在很多客户端同时连接时，进行回调消息验证时，会出现信息残缺，我的解决方案是使用延时策略，但是这并不是长久之计。
按照官方给的例子：
服务端发送数据：
void Server::sendFortune()
{
QByteArray block;
QDataStream out(&block, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_4_0);
out << (quint16)0;
out << fortunes.at(qrand() % fortunes.size());
out.device()->seek(0);
out << (quint16)(block.size() - sizeof(quint16));
QTcpSocket *clientConnection = tcpServer->nextPendingConnection();
connect(clientConnection, SIGNAL(disconnected()),
clientConnection, SLOT(deleteLater()));
clientConnection->write(block);
clientConnection->disconnectFromHost();
}
客户端接受数据：
void Client::readFortune()
{
QDataStream in(tcpSocket);
in.setVersion(QDataStream::Qt_4_0);
if (blockSize == 0) {
if (tcpSocket->bytesAvailable() < (int)sizeof(quint16))
return;
in >> blockSize;
}
if (tcpSocket->bytesAvailable() < blockSize)
return;
QString nextFortune;
in >> nextFortune;
if (nextFortune == currentFortune) {
QTimer::singleShot(0, this, SLOT(requestNewFortune()));
return;
}
currentFortune = nextFortune;
statusLabel->setText(currentFortune);
getFortuneButton->setEnabled(true);
}
缺点是每收发一回合信息，都要重连一次。
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