log4j. Properties log details

1) Import log4j rely on
Here are my imported dependencies ：

<dependency>
          <groupId>log4j</groupId>
          <artifactId>log4j</artifactId>
          <version>1.2.12</version>
      </dependency>

2) add to log4j.properties

# ROOTER
log4j.rootLogger=DEBUG,CONSOLE,FILE

# CONSOLE
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%-d{
    yyyy-MM-dd HH\:mm\:ss} %-5p %-20c %x %m%n

# FILE
log4j.appender.FILE=org.apache.log4j.RollingFileAppender
log4j.appender.FILE.File=logs.log
log4j.appender.FILE.MaxBackupIndex=20
log4j.appender.FILE.MaxFileSize=10MB
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.ConversionPattern=%-d{
    yyyy-MM-dd HH\:mm\:ss} %-5p %-20c %x %m%n

# ERROR
log4j.appender.ERR = org.apache.log4j.DailyRollingFileAppender
log4j.appender.ERR.File =error.log
log4j.appender.ERR.Append = true
log4j.appender.ERR.Threshold = ERROR
log4j.appender.file.DatePattern='.'yyyy-MM-dd'.log'
log4j.appender.ERR.layout = org.apache.log4j.PatternLayout
log4j.appender.ERR.layout.ConversionPattern = %-d{
    yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

Appender
 Log output , Configure the output level of the log 、 Output position, etc , It includes the following categories ：
ConsoleAppender: 		 Log output to the console ;
FileAppender：		 output to a file ;
RollingFileAppender：	 output to a file , When the file reaches a certain threshold , Automatically back up log files ;
DailyRollingFileAppender： Log files can be backed up regularly , By default, one file a day , It can also be set to one per minute 、 One per hour ;
WriterAppender：		 You can customize the log output location .

 The level of logging 
 General log levels include ：ALL,DEBUG, INFO, WARN, ERROR,FATAL,OFF
Log4J Recommended ：DEBUG, INFO, WARN, ERROR



Layout： Log output format ,Log4j Provided layout There are the following ：
org.apache.log4j.HTMLLayout（ With HTML Tabular layout ）,
org.apache.log4j.PatternLayout（ The layout mode can be specified flexibly ）,
org.apache.log4j.SimpleLayout（ Contains the level of log information and the information string ）,
org.apache.log4j.TTCCLayout（ Include the time when the log was generated 、 Threads 、 Categories and so on ）

 Output format 
Log4J The most commonly used log output format is ：org.apache.log4j.PatternLayOut, The main parameters are ：
%n -  Line break 
%m -  Log contents 
%p -  The level of logging (FATAL, ERROR,WARN, INFO,DEBUG or custom)
%r -  The number of milliseconds since the program started 
%t -  Current thread name 
%d -  Date and time ,  Generally use the format  %d{
    yyyy-MM-dd HH:mm:ss, SSS}
%l -  Where the output log event occurred ,  Same as  %F%L%C%M
%F - java  The source file name 
%L - java  Source lines 
%C - java  Class name ,%C{
    1}  Output the last element 
%M - java  Method name 

Logger log  = Logger.getLogger( The current class .class);
if(log.isDebugEnabled()){
    
log.debug("...");
}
if(log.isInfoEnabled()){
    
log.info("...");
}
...

3) Write a log section

/** * Log4j Log output section  */
@Aspect
@Component
public class Log4jAspect {
    

    // Create a log object 
    private Logger logger = Logger.getLogger(Log4jAspect.class);

    // To all service Class plus log trace 
    @Pointcut("execution(* com.blb.aop_demo.service.*Service.*(..))")
    public void logPointcut(){
    
    }

    // Configure surround notification 
    @Around("logPointcut()")
    public Object aroundLog(ProceedingJoinPoint point) throws Throwable {
    
        // Record the time before the method is executed 
        long start = System.currentTimeMillis();
        // Print method name 
        if(logger.isDebugEnabled()){
    
            logger.debug(" Current execution method ：" + point.getSignature().getName());
        }
        // Printing parameters 
        Object[] args = point.getArgs();
        for(Object arg : args){
    
            if(logger.isDebugEnabled()){
    
                logger.debug(" Parameters ："+arg);
            }
        }
        // Print return value 
        Object result = point.proceed();
        if(logger.isDebugEnabled()){
    
            logger.debug(" Method return value ：" +result);
        }
        // Print execution time 
        long end = System.currentTimeMillis();
        if(logger.isDebugEnabled()){
    
            logger.debug(" Method execution time ：" +(end - start));
        }
        return result;
    }
}