QSharedMemory使用例子

#include "mainwindow.h" #include "ui_mainwindow.h" //注意：读取方打开方式为Open QSystemSemaphore MainWindow::s_freeSystemSem("freeSemaphore", 1, QSystemSemaphore::Open); QSystemSemaphore MainWindow::s_usedSystemSem("usedSemaphore", 1, QSystemSemaphore::Open); MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { ui->setupUi(this); this->setWindowTitle("Read ShareMemory"); connect(this,SIGNAL(sigExit()),this,SLOT(slotExit())); connect(this,SIGNAL(sigRecvData(QString)),this,SLOT(slotRecvData(QString))); initShareMem(); m_pCReadThread = new CShareMemReadThread(this); m_pCReadThread->start(); } MainWindow::~MainWindow() { delete ui; detachShareMem(); } void MainWindow::slotExit() { qApp->exit(); } void MainWindow::slotRecvData(QString data) { if(0 == data.compare(tr("app exit"))) { qApp->exit(); return; } ui->textBrowser->append(data); } void MainWindow::notifyRecvData() { emit sigRecvData(tr(m_recvBuf)); } void MainWindow::notifyExit() { emit sigExit(); } /************************************************************ 功能：初始化共享内存 参数： 返回：>=0，成功； <0，失败 作者：刘远安 2015-06-23 ************************************************************/ int MainWindow::initShareMem() { int ret = -1; m_sharedMem.setKey("FrontCommunicationSharedMemory"); if (m_sharedMem.isAttached()) { if(!m_sharedMem.detach()) { qWarning("WriteSharedMemory : detach failed."); return ret; } } else { qWarning("ReadSharedMemory:: attach success."); } return 0; } /************************************************************ 功能：释放共享内存 参数： 返回：>=0，成功； <0，失败 作者：刘远安 2015-06-23 ************************************************************/ int MainWindow::detachShareMem() { int ret = -1; if (m_sharedMem.isAttached()) { qWarning("ShareMem is attached"); if(!m_sharedMem.detach()) { qWarning("WriteSharedMemory:: detach failed."); return ret; } else { qWarning("WriteSharedMemory:: detached success."); } } return 0; } /************************************************************ 功能：读取共享内存数据 参数： 返回：>=0，成功； <0，失败 作者：刘远安 2015-06-23 ************************************************************/ int MainWindow::readShareMem() { int ret = -1; if(m_sharedMem.isAttached()) { qWarning("ReadSharedMemory:: haved attached."); } else { if(!m_sharedMem.attach()) { //If an attempt of reading from the shared memory before data is written QSharedMemory::SharedMemoryError m = m_sharedMem.error(); qWarning("ReadSharedMemory:: attach failed."); return ret; } else { qWarning("ReadSharedMemory:: attach success."); } } s_usedSystemSem.acquire(); m_sharedMem.lock(); char *buf = (char*)m_sharedMem.constData(); m_recvLen = strlen(buf); if(m_recvLen > 0) { memset(m_recvBuf,0,sizeof(m_recvBuf)); memcpy(m_recvBuf,buf,m_recvLen); } //清空缓存 buf = (char*)m_sharedMem.data(); memset(buf,0,m_sharedMem.size()); m_sharedMem.unlock(); s_freeSystemSem.release(); return m_recvLen; } CShareMemReadThread::CShareMemReadThread(MainWindow *pMainWindow) { m_pMainWindow = pMainWindow; } CShareMemReadThread::~CShareMemReadThread() { } void CShareMemReadThread::run() { while (1) { int readLen = m_pMainWindow->readShareMem(); qWarning("readLen=%d",readLen); if(readLen > 0) { m_pMainWindow->notifyRecvData(); } msleep(100); } return; }