log4cpp：定制日志格式，输出日志

一、配置文件

      log.conf：

#a simple test config
log4cpp.rootCategory=DEBUG, rootAppender

#print to File
#log4cpp.appender.rootAppender=RollingFileAppender
#log4cpp.appender.rootAppender.fileName=rootAppender.log #path is ok !  eg: /usr/local/rootAppender.log 
#log4cpp.appender.rootAppender.maxFileSize=1024*1024   # 200 bytes, 1M=1024*1024
#log4cpp.appender.rootAppender.maxBackupIndex=2   #file numbers
#log4cpp.appender.rootAppender.layout=PatternLayout 
#log4cpp.appender.rootAppender.layout.ConversionPattern=%d [%p] %m%n 

#print to Console
log4cpp.appender.rootAppender=ConsoleAppender
log4cpp.appender.rootAppender.layout=PatternLayout
log4cpp.appender.rootAppender.layout.ConversionPattern=%d [%p] - %m%n

二、代码

      logger.h：

#ifndef _LOGGER_H
#define _LOGGER_H

#include <string>
using namespace std;

#ifdef USE_LOG4CPP
#include "log4cpp/Category.hh"
#include "log4cpp/CategoryStream.hh"
#include "log4cpp/PropertyConfigurator.hh"

using namespace log4cpp;
#elif defined USE_LOG4CXX
#include <log4cxx/logger.h>
#include <log4cxx/propertyconfigurator.h>
using namespace log4cxx;
#endif

#define LoggerName "MyApp"
#define AppenderName "rootAppender"

//使用的时候，通过定义不同的宏来使用不同的库，例如使用log4cpp，编译的时候，
//使用-DUSE_LOG4CPP宏，并在链接的时候，使用-llog4cpp进行库链接；同理使用log4cxx
//LOG4CPP_INFO_S 时log4cpp为了方便封装定义的宏
#ifdef USE_LOG4CPP

extern log4cpp::Category *logger_;
#define LOG_DEBUG(msg) \
    LOG4CPP_DEBUG_S((*logger_))<<msg<<"("<<__FILE__<<":"<<__LINE__<<")";
#define LOG_INFO(msg) \
    LOG4CPP_INFO_S((*logger_))<<msg<<"("<<__FILE__<<":"<<__LINE__<<")";
#define LOG_WARN(msg) \
    LOG4CPP_WARN_S((*logger_))<<msg<<"("<<__FILE__<<":"<<__LINE__<<")";
#define LOG_ERROR(msg) \
    LOG4CPP_ERROR_S((*logger_))<<msg<<"("<<__FILE__<<":"<<__LINE__<<")";
#define LOG_FATAL(msg) \
    LOG4CPP_FATAL_S((*logger_))<<msg<<"("<<__FILE__<<":"<<__LINE__<<")";

#elif defined USE_LOG4CXX

extern LoggerPtr logger_;
#define LOG_DEBUG(msg) \
{\
    stringstream temp_; \
    temp_<<msg<<"("<<__FILE__<<":"<<__LINE__<<")"; \
    LOG4CXX_DEBUG(logger_, temp_.str()); \
}
#define LOG_INFO(msg) \
{\
    stringstream temp_; \
    temp_<<msg<<"("<<__FILE__<<":"<<__LINE__<<")"; \
    LOG4CXX_INFO(logger_, temp_.str()); \
}
#define LOG_WARN(msg) \
{\
    stringstream temp_; \
    temp_<<msg<<"("<<__FILE__<<":"<<__LINE__<<")"; \
    LOG4CXX_WARN(logger_, temp_.str()); \
}
#define LOG_ERROR(msg) \
{\
    stringstream temp_; \
    temp_<<msg<<"("<<__FILE__<<":"<<__LINE__<<")"; \
    LOG4CXX_ERROR(logger_, temp_.str()); \
}
#define LOG_FATAL(msg) \
{\
    stringstream temp_; \
    temp_<<msg<<"("<<__FILE__<<":"<<__LINE__<<")"; \
    LOG4CXX_FATAL(logger_, temp_.str()); \
}

#endif

void InitLog(const char *conf_file);
string mformat(const char *fmt, ...);

#endif /*_LOGGER_H*/

      logger.cpp：

#include "logger.h"

#ifdef USE_LOG4CPP
log4cpp::Category *logger_;
#elif defined USE_LOG4CXX
LoggerPtr logger_(Logger::getLogger(LoggerName));
#endif

void InitLog(const char *conf_file)
{
#ifdef USE_LOG4CPP
    log4cpp::PropertyConfigurator::configure(conf_file);
    log4cpp::Category& log = log4cpp::Category::getInstance(string(AppenderName));
    logger_ = &log;
#elif defined USE_LOG4CXX
    PropertyConfigurator::configure(File(conf_file)); // Configure file, log4j format
    logger_ = Logger::getLogger("org.apache.log4j.RollingFileAppender"); // Appender name
#endif
}

string mformat(const char *fmt, ...)
{
	size_t size = 1024;
	char* buf = new char[size];
	while(1)
	{
		va_list args;
		int n;

		va_start(args, fmt);
		n = vsprintf(buf, fmt, args);
		va_end(args);

		if ((n > -1) && (static_cast<size_t>(n) < size)) 
		{
			std::string s(buf);
			delete [] buf;
			return s;
		}
		// Else try again with more space.
		size = (n > -1) ?
			n + 1 :   // ISO/IEC 9899:1999
		size * 2; // twice the old size

		delete [] buf;
		buf = new char[size];
	}

}

      main.cpp：

#include <iostream>
using namespace std;


#include "logger.h"



int main()
{
 	InitLog("log.conf");
 	LOG_DEBUG("debug");
 	LOG_INFO("info");

	return 0;
}

三、编译

3.1 Windows编译

      属性 -> 配置属性 -> C/C++ -> 预处理器 -> 预处理器定义  加入宏：USE_LOG4CPP。

3.2 Linux编译

      Makefile编译时加入宏：USE_LOG4CPP。

四、输出

      在当前控制台下，输出日志：

            2013-12-13 16:19:25,431 [DEBUG] - debug(fast_dr302.cpp:12)
            2013-12-13 16:19:25,431 [INFO] - info(fast_dr302.cpp:13)

      修改配置文件log.conf，可将该日志输出到rootAppender.log文件中。