Log4Qt

Log4Qt - Logging for the Qt cross-platform application framework

Continuous Integration

Description

Log4Qt is a C++ port of the Apache Software Foundation Log4j package using the Qt Framework. It is intended to be used by open source and commercial Qt projects.

Original project

http://log4qt.sourceforge.net/

This Log4Qt repository is a clone of the Log4Qt repository from https://gitorious.org/log4qt which was itself a clone of the original Log4Qt project on SourceForge http://sourceforge.net/projects/log4qt/ (http://log4qt.sourceforge.net/).

Additional features

• JSON configuration support (log4qt.json) alongside the classic .properties format
• XML configuration support (log4qt.xml) alongside .properties and .json formats
• Pluggable TriggeringPolicy / RolloverStrategy for RollingFileAppender (log4j2-style): size-based, time-based, cron-based, and on-startup triggering policies with composable OR-combination and a fixed-window numbered rollover strategy
• SimpleTimeLayout (“dd.MM.yyyy hh:mm [Thread] Level Logger Message”)
• ColorConsoleAppender (render colorized message by escape sequence and put it to console)
• SignalAppender (emit signal when log event happens)
• DatabaseAppender (append log event into sql table)
• DatabaseLayout (put log event into sql table columns)
• Telnet appender (append log event to telnet clients)
• LogStream (qDebug()-style log messages appending)
• MainThreadAppender (Proxy appender for sending log messages through event loop)
• XMLLayout to support apache chainsaw
• DailyRollingFileAppender which generates a logfile for each day (add current date formatted to the filename)
• Binary logger
• Windows Debug Console Appender

JSON Configuration

As an alternative to log4qt.properties, you can use a log4qt.json file:

{
    "log4j": {
        "rootLogger": "DEBUG, console",
        "appender": {
            "console": {
                "type": "org.apache.log4j.ConsoleAppender",
                "target": "STDOUT_TARGET",
                "layout": {
                    "type": "org.apache.log4j.TTCCLayout",
                    "dateFormat": "ISO8601"
                }
            }
        },
        "logger": {
            "MyApp": "ERROR, console"
        },
        "additivity": {
            "MyApp": "false"
        }
    }
}

Nested objects produce dot-separated property keys, and the type key sets the class (appender, layout, filter, …) for the parent object — not class or @class. The value accepts the legacy org.apache.log4j.* names, the Log4Qt::* names, or the short aliases (e.g. Console, TTCCLayout). Place the file next to your executable or in the working directory. When both log4qt.properties and log4qt.json exist, the .properties file takes priority.

You can also configure programmatically:

#include 

Log4Qt::JsonConfigurator::configure("path/to/config.json");
// or with file watching:
Log4Qt::JsonConfigurator::configureAndWatch("path/to/config.json");

XML Configuration

As an alternative to .properties and .json, you can use a log4qt.xml file:

    DEBUG, console
    
        
            org.apache.log4j.ConsoleAppender
            STDOUT_TARGET
            
                org.apache.log4j.TTCCLayout
                ISO8601
            
        
    
    
        ERROR, console
    
    
        false
    

Nested elements produce dot-separated property keys, and a `` element sets the class for the parent element — not a class attribute as in Log4j's XML. (Attributes flatten to child properties, so type="..." as an attribute also works, but class="..." does not.) Priority order: .properties > .json > .xml.

You can also configure programmatically:

#include 

Log4Qt::XmlConfigurator::configure("path/to/config.xml");
// or with file watching:
Log4Qt::XmlConfigurator::configureAndWatch("path/to/config.xml");

Requirements

• Minimum Qt version required Qt 6.5 (for support of Qt versions down to 5.3 use branch 1.4 or the latest 1.4.x release or for support of Qt versions down to 5.7 use branch 1.6 or the latest 1.5.x release) Note: Qt 6.5 needs Visual Studio 2022 on Windows/MSVC — Qt 6.5.3, the last open source 6.5 patch, does not compile with the Visual Studio 2026 toolchain (its headers use the stdext array iterators that MSVC removed).
• C++20 required (minimum compiler version MSVC 19.29 (Visual Studio 2019 16.11), GCC 10, or Clang 10)

License

Apache License 2, Version 2.0

Clone

git clone https://github.com/MEONMedical/Log4Qt.git

Build and install

cmake

cmake is used to build Log4Qt. An out-of-source build is required:

mkdir Log4Qt-build
cd Log4Qt-build
cmake ../Log4Qt
make/mingw32-make/msbuild Log4Qt.sln
make/mingw32-make install

Addition cmake options are
    * '-DBUILD_SHARED_LIBS=OFF' to build static log4qt lib (default: ON)
    * '-DBUILD_WITH_DB_LOGGING=ON|OFF to build with database logging support (default: OFF)
    * '-DBUILD_WITH_TELNET_LOGGING=ON|OFF to build with telnet appender support (default: ON)
    * '-DBUILD_WITH_QML_LOGGING=ON|OFF to build with qml logger support (default: ON)