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项目日志——Log4cpp

• 开源的C++类库Log4cpp提供了很多功能，帮助我们的应用程序更方便地记录日志。

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安装与构建

• Log4cpp官网——http://log4cpp.sourceforge.net/

wget https://nchc.dl.sourceforge.net/project/log4cpp/log4cpp1.1.x%20%28new%29/log4cpp-1.1/log4cpp-1.1.3.tar.gz

tar zxvf log4cpp-1.1.3.tar.gz
cd log4cpp
# root用户
./configure --prefix=执行路径  
# 示例   
# ./configure --prefix=/home/xuanxuan/share_bike/third/lib/log4cpp
make
make install

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使用

• 包含头文件

#include <log4cpp/Category.hh>
#include <log4cpp/FileAppender.hh>
#include <log4cpp/PatternLayout.hh>
#include <log4cpp/OstreamAppender.hh>

• 初始化日志输出的目的地

示例1:输出到标准输出std::cout

log4cpp::Appender *appender = new log4cpp::OstreamAppender("root", &std::cout);

示例2:输出到log文件

log4cpp::Appender *appender = new log4cpp::FileAppender("root", "test.log");

输出方式如下:

log4cpp::FileAppender // 输出到文件
log4cpp::RollingFileAppender // 输出到回卷文件，即当文件到达某个大小后回卷
log4cpp::OstreamAppender // 输出到一个ostream类
log4cpp::RemoteSyslogAppender // 输出到远程syslog服务器
log4cpp::StringQueueAppender // 内存队列
log4cpp::SyslogAppender // 本地syslog
log4cpp::Win32DebugAppender // 发送到缺省系统调试器
log4cpp::NTEventLogAppender // 发送到win 事件日志

注意：

实际上日志输出到终端或文件中是很慢的，可能会引起IO中断,所以我们可以先输出到内存中(StringQueueAppender),然后在输出到其它地方，这样效率较高。

• 设置日志输出格式

log4cpp::PatternLayout *patternLayout = new log4cpp::PatternLayout();
patternLayout->setConversionPattern("%d [%p] - %m%n");
appender->setLayout(patternLayout);

日志输出格式控制如下:

log4cpp::PatternLayout Class Reference

%%%% - a single percent sign
%c - the category
%d - the date
Date format: The date format character may be followed by a date format specifier enclosed between braces. For example, %d{%H:%M:%S,%l} or %d{%d %m %Y %H:%M:%S,%l}. If no date format specifier is given then the following format is used: "Wed Jan 02 02:03:55 1980". The date format specifier admits the same syntax as the ANSI C function strftime, with 1 addition. The addition is the specifier %l for milliseconds, padded with zeros to make 3 digits.
%m - the message
%n - the platform specific line separator
%p - the priority
%r - milliseconds since this layout was created.
%R - seconds since Jan 1, 1970
%u - clock ticks since process start
%x - the NDC

• 设置输出类别和日志优先级

log4cpp::Category &root = log4cpp::Category::getRoot();
root.setPriority(log4cpp::Priority::NOTICE);
root.addAppender(appender);

日志的级别如下:

NOTSET < DEBUG < INFO < NOTICE < WARN < ERROR < CRIT < ALERT < FATAL = EMERG。
低于该级别的日志不会被记录。

• 定义宏来减少代码量

#define LOG(__level) log4cpp::Category::getRoot() << log4cpp::Priority::__level << __FILE__ << " " << __LINE__ << ": "

使用:

LOG(DEBUG)<<"DEBUG.";

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测试

什么是单例？

• 程序中仅有一个的对象。

配置文件:log.conf

#定义Root category的属性
log4cpp.rootCategory=DEBUG, RootLog#定义RootLog属性
log4cpp.appender.RootLog=RollingFileAppender
log4cpp.appender.RootLog.layout=PatternLayoutlog4cpp.appender.RootLog.layout.ConversionPattern=%d{%m-%d %H:%M:%S %l} [%t][%p]%m%n
log4cpp.appender.RootLog.fileName=/var/log/share_bike.log
log4cpp.appender.RootLog.maxFileSize=268435456 #256MB
log4cpp.appender.RootLog.fileNamePattern=share_bike_%i.log
log4cpp.appender.RootLog.maxBackupIndex=256

• 封装为一个类

Logger.h

#ifndef DISTRIBUTED_LOGGER_H_
#define DISTRIBUTED_LOGGER_H_#include <string>
#include <log4cpp/Category.hh>class Logger{
public:bool init(const std::string& log_conf_file);static Logger* instance(){//返回单例——全局唯一对象return &instance_;}log4cpp::Category* GetHandle(){return category_;}protected:static Logger instance_;log4cpp::Category* category_;
};#define LOG_INFO Logger::instance()->GetHandle()->info
#define LOG_DEBUG Logger::instance()->GetHandle()->debug
#define LOG_ERROR Logger::instance()->GetHandle()->error
#define LOG_WARN Logger::instance()->GetHandle()->warn#endif

Logger.cpp

#include "Logger.h"#include <iostream>
#include <log4cpp/Category.hh>
#include <log4cpp/FileAppender.hh>
#include <log4cpp/PatternLayout.hh>
#include <log4cpp/OstreamAppender.hh>
#include <log4cpp/PropertyConfigurator.hh>Logger Logger::instance_;bool Logger::init(const std::string& log_conf_file){try{log4cpp::PropertyConfigurator::configure(log_conf_file);}catch(log4cpp::ConfigureFailure& f){std::cerr << " load log config file " << log_conf_file.c_str() << " failed with result : " << f.what()<< std::endl;return false;}category_ = &log4cpp::Category::getRoot();return true;
}

• 测试

main.cpp

#include "iniconfig.h" //注意路径，会在CMake中进行调整
#include "configdef.h"
#include "Logger.h"int main(int argc,char** argv){if(argc != 3){//缺少参数printf("Please input shbk <config file path> <log file config>!\n");return -1;}if(!Logger::instance()->init(std::string(argv[2]))){fprintf(stderr,"init log module failed.\n");return -2;}Iniconfig config;if(!config.loadfile(std::string(argv[1]))){//printf("load %s failed.\n",argv[1]);LOG_ERROR("load %s failed.",argv[1]);return -3;}//测试是否读取成功st_env_config conf_args = config.getconfig();LOG_INFO("[database]ip:%s\n [database]port:%d\n [database]user:%s\n [database]pwd:%s\n [database]db:%s\n [server]port:%d\n ",conf_args.db_ip.c_str(),conf_args.db_port,conf_args.db_user.c_str(),conf_args.db_pwd.c_str(),conf_args.db_name.c_str(),conf_args.svr_port);return 0;
}

**注意链接库:**下面为示例，请根据自身情况调整。

TARGET_LINK_LIBRARIES(common log4cpp)

TARGET_LINK_LIBRARIES(share_bike pthread)
TARGET_LINK_LIBRARIES(${PROJECT_NAME} liblog4cpp.a)

执行:

./share_bike ../conf/share_bike.ini ../conf/log.conf

查看:

在log.conf中。/var/log/share_bike.log为保存路径。

log4cpp.appender.RootLog.fileName=/var/log/share_bike.log