通常情况下，linux下的后台程序不需要GUI进行展示，而前台程序往往有个界面，方便和用户的交互。本文所演示的例子，是QT 程序和后台linux进程（C语言）交互，通过socket传输的内容是结构体。因为QT本身是跨平台的框架，因此以后前端程序移植到其它平台依然能很好的运行。
结构体的定义如下：
struct Test
{
int a;
char b;
};
QT程序：windows系统，使用QT提供的服务器类QTCPServer 、QTcpSocket和相关函数。
linux下的C程序：通过linux提供的socket编程接口，连接服务器，并发送结构体。
QT程序的关键代码如下：
void TcpServerDemo::on_listenButton_clicked()
{
this->tcpServer = new TcpServer(this);
QString ip;
ip = ui->ipLineEdit->text();
QString port ;
port = ui->portLineEdit->text();
if (! this->tcpServer->listen(QHostAddress(ip), (quint16)(port.toInt())))
{
QMessageBox::warning(this, tr("tcp server"),
tr("listen error:%1").arg(this->tcpServer->errorString()));
return;
}
ui->listenButton->setEnabled(false);
}
void TcpServer::incomingConnection ( int socketDescriptor )
{
this->tcpSocket = new QTcpSocket(this);
this->tcpSocket->setSocketDescriptor(socketDescriptor);
QObject::connect(this->tcpSocket, SIGNAL(readyRead()),
this, SLOT(on_ready_read()));
}
void TcpServer::on_ready_read()
{
struct Test t;
this->tcpSocket->read((char *)&t,sizeof(t));
QMessageBox::warning(NULL, tr("tcp server"),
tr("a=%1 b=%2").arg(t.a).arg(t.b));
}
linux下C程序的关键代码：
int sockfd;
struct sockaddr_in servaddr;//, myaddr;
struct Test* p;
char buf[N] = {0};
ssize_t n;
if (argc != 3)
{
printf("usage:%s serverip serverport\n", argv[0]);
return 0;
}
if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1)
{
perror("socket");
return -1;
}
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = PF_INET;
servaddr.sin_port = htons(atoi(argv[2]));//error htons("6000");
servaddr.sin_addr.s_addr = inet_addr(argv[1]);
if (-1 == connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)))
{
perror("connect");
return -1;
}
p = (struct Test *)buf;
printf("input a b:");
scanf("%d", &p->a);
getchar();
scanf("%c", &p->b);
printf("a=%d b=%d\n", p->a, p->b);
if (-1 == send(sockfd, p, sizeof(buf), 0))
{
perror("send");
return -1;
}
memset(buf, 0, N);
if ((n = recv(sockfd, buf, N, 0)) == -1)
{
perror("recv");
return -1;
}
p = (struct Test *)buf;
printf("a=%d b=%c", p->a, p->b);
printf(">");
close(sockfd);