Log (slf4j, log4j)

• Common logging framework

Laog4j:

Log4j2：

SLF4J: log output interfaces, dependent on other underlying logging framework

Logback：

Apache Commons Logging: slf4j and the like, an output interface is the log, log frameworks rely on third parties

java.util.logging.Logger: JDK comes with the system log

 

Generally used in the project as a log slf4j abstract, so that later replace the log framework system, then you need only replace the JAR, without modifying the code.

 

 

• slf4j

slf4j just a log output to provide a unified interface for the Java program, logging is not a specific implementation, such as JDBC, like it, is just a rule only, so slf4j alone will not work,

The logs must be used with other specific implementations, such as log4j or log4j2

• slf4j + log4j

Required jar: log4j-xxx.jar slf4j-api-xxx.jar slf4j-log4j12-xx.jar (bridging package)

log4j log output level:

TRACE > DEBUG > INFO > WARN > ERROR > FATAL 

But note that there is no FATAL level slf4j

 

com.basic.work.log Package; 

Import org.slf4j.Logger; 
Import org.slf4j.LoggerFactory; 


/ * * 
 * 
 * + log4j combination SLF4J 
 * required jar: log4j-xxx.jar slf4j-api -xxx.jar slf4j xx.jar--log4j12 
 * 
 * slf4j just a log output to provide a unified interface for the Java program, logging is not a specific implementation, 
 * it such as JDBC, it is only a rule, it is not working alone slf4j and 
 * must be used with other specific log implementation, such as log4j or log4j2 
 * 
 output levels * log: 
 * the TRACE> DEBUG> INFO> WARN> ERROR> FATAL 
 * 
 * Note slf4j no rating FATAL 
 * @author chenzhubing 
 * 
 * / 
public  class Log4j { 

    Private  static Final Logger LoggerFactory.getLogger = log (Log4j. class);
    
    public static void main(String[] args) {
        log.info("hekk");
        log.warn("warn");
        log.error("sssss");
        log.trace("trace");
        log.debug("debug");
        
        
        
    }
    
}

 

 

• log4j.properties

  = Log4j.rootLogger the TRACE, XXX, yyy, ZZZ, CCC 
  
  #xxx stands for console 
  log4j.appender.xxx = org.apache.log4j.ConsoleAppender tells that 
  #PatternLayout flexibility to the information string specified level and pattern layout log information SimpleLayout 
  log4j.appender .xxx.layout = Org.apache.log4j.PatternLayout 
  log4j.appender.xxx.layout.ConversionPattern = (% R & lt MS) [% T]% -5p:% C% X #% m:% m% n- 
  
  #yyy representative file 
  log4j.appender.yyy = org.apache.log4j.FileAppender 
  log4j.appender.yyy.layout = Org.apache.log4j.PatternLayout 
  log4j.appender.yyy.layout.ConversionPattern = (% R & lt MS) [% T]% -5p :% C% X #% m:% m% n- 
  log4j.appender.yyy.File = F: /FileAppender.log 
  
  
  #zzz representatives DailyRollingFileAppender create a file every day 
  log4j.appender.zzz = org.apache.log4j.DailyRollingFileAppender 
  log4j.appender.zzz.layout = org.apache.log4j.PatternLayout 
  log4j.appender.zzz.layout.ConversionPattern = ( MS R & lt%) [% T]% -5p:% C% X #% m:% m% n- 
  log4j.appender.zzz.File = F: / log4j- DailyRollingFileAppender.log 
  # defaults to true appended to the file; to false cover the original file 
  log4j.appender.zzz.Append = false 
  
  #ccc representatives RollingFileAppender file reaches the specified size, create a new file 
  log4j.appender.ccc = org.apache.log4j.RollingFileAppender 
  log4j.appender.ccc.layout =Org.apache.log4j.PatternLayout 
  log4j.appender.ccc.layout.ConversionPattern = (% R & lt MS) [% T]% -5p:% C% X #% M:% m% n- 
  log4j.appender.ccc.File = F : / log4j- RollingFileAppender.log 
  maximum size # specified file exceeds the maximum size will generate a new file [file size corresponds to a maximum time of occurrence of the oldest, smallest file size corresponds to the most recent time occurred] 
  log4j.appender.ccc .MaxFileSize = 50kB 
  # retain up to 50 most recent occurrence of the file 
  log4j.appender.ccc.MaxBackupIndex = 50