windows下QT前台和linux下后台程序通过socket通信

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);

windows下QT前台和linux下后台程序通过socket通信