下载与安装

https://sourceforge.net/projects/log4cpp/

tar xvf log4cpp-1.1.3.tar.gz
cd log4cpp
./configure
make 
make check
make install
ldconfig

头文件位于/usr/local/include/log4cpp/
库文件位于/usr/local/lib/

log4cpp框架

Category

Appender

1. ⽇志输出到控制台

OstreamAppender(const std::string& name, std::ostream* stream);

2. ⽇志输出到本地⽂件

FileAppender(const std::string& name, const std::string& fileName,
                     bool append = true, mode_t mode = 00644);

3. ⽇志通过⽹络输出到远程服务器

RemoteSyslogAppender(const std::string& name, 
                             const std::string& syslogName, 
                             const std::string& relayer, 
                             int facility = LOG_USER,
                             int portNumber = 514);

4. 日志输出到系统日志

SyslogAppender(const std::string& name, const std::string& syslogName, 
                       int facility = LOG_USER);

5. 日志输出到String队列

StringQueueAppender(const std::string& name);

6. 日志输出到Buffer

BufferingAppender(const std::string name, unsigned long max_size, std::auto_ptr<Appender> sink,
                           std::auto_ptr<TriggeringEventEvaluator> evaluator);

7. 日志在规定大小的文件中回滚输入

RollingFileAppender::RollingFileAppender(const std::string& name,
                                             const std::string& fileName, 
                                             size_t maxFileSize, 
                                             unsigned int maxBackupIndex,
                                             bool append,
                                             mode_t mode) :

8. ……（可定制）

Layout

日志格式模板

1. Basic layout

/**
     * BasicLayout is a simple fixed format Layout implementation. 
     **/
    class LOG4CPP_EXPORT BasicLayout : public Layout {
        public:
        BasicLayout();
        virtual ~BasicLayout();

        /**
         * Formats the LoggingEvent in BasicLayout style:<br>
         * "timeStamp priority category ndc: message"
         **/
        virtual std::string format(const LoggingEvent& event);
    };        

2. simple layout

/**
     * BasicLayout is a simple fixed format Layout implementation. 
     **/
    class LOG4CPP_EXPORT SimpleLayout : public Layout {
        public:
        SimpleLayout();
        virtual ~SimpleLayout();

        /**
         * Formats the LoggingEvent in SimpleLayout style:<br>
         * "priority - message"
         **/
        virtual std::string format(const LoggingEvent& event);
    };        

3. Pattern layout

/**
     * PatternLayout is a simple fixed format Layout implementation. 
     **/
    class LOG4CPP_EXPORT PatternLayout : public Layout {
        public:
        /**
           The default conversion pattern
        **/
        static const char* DEFAULT_CONVERSION_PATTERN;

        /**
           A conversion pattern equivalent to the SimpleLayout.
        **/
        static const char* SIMPLE_CONVERSION_PATTERN;

        /**
           A conversion pattern equivalent to the BasicLayout.
        **/
        static const char* BASIC_CONVERSION_PATTERN;

        /**
           A conversion pattern equivalent to the TTCCLayout.
           Note: TTCCLayout is in log4j but not log4cpp.
        **/           
        static const char* TTCC_CONVERSION_PATTERN;

        PatternLayout();
        virtual ~PatternLayout();
        
        // NOTE: All double percentage signs ('%%') followed by a character
        //       in the following comments should actually be a single char.
        //       The doubles are included so that doxygen will print them correctly.
        /**
         * Formats the LoggingEvent in the style set by
		 * the setConversionPattern call. By default, set
		 * to "%%m%%n"
         **/
        virtual std::string format(const LoggingEvent& event);

        /**
         * Sets the format of log lines handled by this
         * PatternLayout. By default, set to "%%m%%n".<br>
         * Format characters are as follows:<br>
         * <li><b>%%</b> - a single percent sign</li>
         * <li><b>%%c</b> - the category</li>
         * <li><b>%%d</b> - the date\n
         *  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.</li>
         * <li><b>%%m</b> - the message</li>
         * <li><b>%%n</b> - the platform specific line separator</li>
         * <li><b>%%p</b> - the priority</li>
         * <li><b>%%r</b> - milliseconds since this layout was created.</li>
         * <li><b>%%R</b> - seconds since Jan 1, 1970</li>
         * <li><b>%%u</b> - clock ticks since process start</li>
         * <li><b>%%x</b> - the NDC</li>
         * @param conversionPattern the conversion pattern
         * @exception ConfigureFailure if the pattern is invalid
         **/
        virtual void setConversionPattern(const std::string& conversionPattern);

        virtual std::string getConversionPattern() const;

        virtual void clearConversionPattern();

        class LOG4CPP_EXPORT PatternComponent {
            public:
            inline virtual ~PatternComponent() {};
            virtual void append(std::ostringstream& out, const LoggingEvent& event) = 0;
        };

        private:
        typedef std::vector<PatternComponent*> ComponentVector; 
        ComponentVector _components;

        std::string _conversionPattern;
    };     

4. PassThroughLayout

class PassThroughLayout : public Layout
   {
      public:
         virtual std::string format(const LoggingEvent& event) { return event.message; }
   };

Priorty

Output

三种输出风格

warn_log.log(log4cpp::Priority::WARN, "This will be a logged warning, darren = %d", 100);
warn_log.warnStream() << "This will be a logged warning, darren = " << 100;
warn_log.alert("Alert info");

功能

日志级别

日志等级值越小，打印等级越高

typedef enum {
	EMERG = 0,
	FATAL = 0,
	ALERT = 100,
	CRIT = 200,
	ERROR = 300,
	WARN = 400,
	NOTICE = 500,
	INFO = 600,
	DEBUG = 700,
	NOTSET = 800
} PriorityLevel;

⽇志格式化

/*********************************************************************
格式化布局。它的使⽤⽅式类似C语⾔中的printf，使⽤格式化它符串来描述输出格式。⽬前⽀持的转义
定义如下：
%% - 转义字符'%'
%c - Category
%d - ⽇期；⽇期可以进⼀步设置格式，⽤花括号包围，例如%d{%H:%M:%S,%l}。
⽇期的格式符号与ANSI C函数strftime中的⼀致。但增加了⼀个格式符号%l，表示毫秒，占三个
⼗进制位。
%m - 消息
%n - 换⾏符；会根据平台的不同⽽不同，但对⽤户透明。
%p - 优先级
%r - ⾃从layout被创建后的毫秒数
%R - 从1970年1⽉1⽇开始到⽬前为⽌的秒数
%u - 进程开始到⽬前为⽌的时钟周期数
%x - NDC
%t - 线程id
***********************************************************************/

⽇志输出

1. ⽇志输出到控制台
2. ⽇志输出到本地⽂件
3. ⽇志通过⽹络输出到远程服务器
4. ……（可定制）

日志回滚

1. 本地⽇志⽀持最⼤⽂件限制
2. 当本地⽇志到达最⼤⽂件限制的时候新建⼀个⽂件
3. 每天⾄少⼀个⽂件

日志配置文件

该功能可以将日志打印建立层级关系，如下图，他们能够同步从上级将日志输出，不同的权限(root、sub1、sub2、sub1.sub1……)可以定制不同的输出方式，比如输出到服务器，比如输出到文件等，是否需要将日志向上级汇报，可以通过配置文件进行设置

1. 加载日志配置文件

log4cpp::PropertyConfigurator::configure("log4cpp_lsy_test.conf");

2. 获取输出层级

log4cpp::Category& root = log4cpp::Category::getRoot();
    log4cpp::Category& sub1 = 
        log4cpp::Category::getInstance(std::string("sub1"));
         log4cpp::Category& sub1 = 
        log4cpp::Category::getInstance(std::string("sub1"));
    log4cpp::Category& sub1_sub2 = 
        log4cpp::Category::getInstance(std::string("sub1.sub2"));

3. 配置是否向上级汇报

# 默认是true，即默认向上级汇报
log4cpp.additivity.sub1=false

4. 配置启用某个层级
   启用层级的时候，可以配置两个参数
   第一个参数：打印等级
   第二个参数：配置对应的adaptor

log4cpp.rootCategory=DEBUG, rootAppender
log4cpp.category.sub1=,A1
log4cpp.category.sub2=INFO
log4cpp.category.sub1.sub2=, A2

5. 设置adaptor

# 配置为控制台输出
log4cpp.appender.rootAppender=org.apache.log4cpp.ConsoleAppender
log4cpp.appender.rootAppender.layout=org.apache.log4cpp.BasicLayout
# 配置为文件输出
log4cpp.appender.A1=org.apache.log4cpp.FileAppender
log4cpp.appender.A1.fileName=A1.log
log4cpp.appender.A1.layout=org.apache.log4cpp.SimpleLayout
# 配置为控制台输出
log4cpp.appender.A2=org.apache.log4cpp.ConsoleAppender
log4cpp.appender.A2.layout=org.apache.log4cpp.PatternLayout
# 配置输出模板
log4cpp.appender.A2.layout.ConversionPattern=%d %p %x - %m%n