Log4Qt使用---自定义输出位置

Log4Qt的一个强大之处在于可以把log同时记录到不同地方，可以是文件、终端和数据库等等，这里介绍如何把log4qt的log记录输出到一个窗口，输出到其他地方也类似。
主要是继承Log4Qt::AppenderSkeleton重新实现里面的几个虚函数。

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1. #ifndef LOGVIEW_H
   #define LOGVIEW_H
   class QTextBrowser;
   /*! \brief root::LogView
           \author Wang Bin <[email]wbsecg1@gmail.com[/email]>
           \version 0.01
           \date 2011.08.03
   
           Log信息显示窗口。
   */
   class LogView : public QWidget
   {
           Q_OBJECT
           LOG4QT_DECLARE_QCLASS_LOGGER
   public:
           LogView(QWidget *parent = 0);
           QTextBrowser *view() const {return mView;}
   public slots:
           void appendLog(const QString &pMessage);
   private:
           QMutex mMutex;
           QTextBrowser *mView;
   };
   class LogViewAppender : public Log4Qt::AppenderSkeleton
   {
       Q_OBJECT
   public:
           LogViewAppender(QObject *pParent = 0);
           ~LogViewAppender();
   signals:
           void OnMessageAppend(const QString& msg);
   protected:
           virtual bool requiresLayout() const;
           virtual void append(const Log4Qt::LoggingEvent &rEvent);
   #ifndef QT_NO_DEBUG_STREAM
           virtual QDebug debug(QDebug &rDebug) const;
   #endif //QT_NO_DEBUG_STREAM
   private:
           LogView *mLogView;
   };
   #endif // LOGVIEW_H

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1. #include "logview.h"
   #include <QtCore/QDebug>
   #include <QtGui/QTextBrowser>
   #include <QtGui/QLayout>
   LogView::LogView(QWidget* parent)
           :QWidget(parent)
   {
           QVBoxLayout *vlayout = new QVBoxLayout;
           setLayout(vlayout);
           qRegisterMetaType<QTextCursor>("QTextCursor");
           mView = new QTextBrowser(this);
           vlayout->addWidget(mView); 
           showMaximized();
   }
   void LogView::appendLog(const QString &pMessage)
   {
           QMutexLocker lock(&mMutex);
           //QString msg = pMessage.trimmed();
           //mView->append(msg);
           mView->insertPlainText(pMessage);
           mView->moveCursor(QTextCursor::End);
           mView->ensureCursorVisible();
   }
   LogViewAppender::LogViewAppender(QObject *parent) :
           Log4Qt::AppenderSkeleton(parent),mLogView(NULL)
   {
   }
   LogViewAppender::~LogViewAppender()
   {
           if (mLogView) {
                   mLogView->close();
                   mLogView = NULL;
           }
   }
   bool LogViewAppender::requiresLayout() const
   {
           return true;
   }
   void LogViewAppender::append(const Log4Qt::LoggingEvent &rEvent)
   {
           Q_ASSERT_X(layout(), "LogViewAppender::append()", "Layout must not be null");
           QString message(layout()->format(rEvent));
           emit OnMessageAppend(message);
           /*if (!mLogView) {
                   mLogView = new LogView;
           }
           mLogView->show(); //
           mLogView->appendLog(message);*/
   }
   #ifndef QT_NO_DEBUG_STREAM
   QDebug LogViewAppender::debug(QDebug &rDebug) const
   {
           return rDebug.space();
   }
   #endif //QT_NO_DEBUG_STREAM

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1. bool InitializeLog4QtView(LogView *widget)
   {
           Log4Qt::Logger *logger = Log4Qt::Logger::rootLogger();
           LogViewAppender *viewappender = new LogViewAppender;
           viewappender->setName("ViewAppender");
           Log4Qt::TTCCLayout *viewlayout = new Log4Qt::TTCCLayout(Log4Qt::TTCCLayout::ISO8601);
           viewlayout->setThreadPrinting(true);
           viewappender->setLayout(viewlayout);
           viewappender->activateOptions();
           logger->addAppender(viewappender);
           QObject::connect(viewappender, SIGNAL(OnMessageAppend(QString)), widget, SLOT(appendLog(QString)));
           return true;
   }
   bool FinalizeLog4Qt()
   {
           Log4Qt::Logger *logger = Log4Qt::Logger::rootLogger();
           logger->removeAllAppenders();
           return true;
   }