Detailed configuration of log4j

  
  Loggers （Logger） Their behavior is hierarchical . It is divided into  
- OFF 
- FATAL 
- WARN 
- INFO 
- DEBUG 
- TRACE 
- ALL 
Log4j It is recommended to use only four levels , The priorities from high to low are ERROR、WARN、INFO、DEBUG. By the level defined here , You can control the switch to the corresponding level of log information in the application . 
For example, it defines INFO Level , Then all of the DEBUG Level log information will not be printed out . 
The program will print logs higher than or equal to the set level , The higher the log level is set , The less logs you print out . 
If you set the level to INFO, The priority is higher than or equal to INFO Level （ Such as ：INFO、WARN、 
ERROR） The log information of will be output , Less than this level DEBUG Will not be output .

log4j.properties File configuration
Code block
log4j.rootLogger = debug , syso , D
### Output to console ###
log4j.appender.syso = org.apache.log4j.ConsoleAppender
log4j.appender.syso.Target = System.out
log4j.appender.syso.Threshold = debug    ## Output DEBUG Log above level
log4j.appender.syso.layout = org.apache.log4j.PatternLayout
log4j.appender.syso.layout.ConversionPattern = %d{[yyyy/MM/dd HH:mm:ss,SSS]} [%5p] [%c:%L] - %m%n
 
### Output to a log file ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = D:/logs/Salary.log
log4j.appender.D.Append = true
### \u8F93\u51FADEBUG\u7EA7\u522B\u4EE5\u4E0A\u7684\u65E5\u5FD7
log4j.appender.D.Threshold = DEBUG    ## Output DEBUG Log above level
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %d{[yyyy/MM/dd HH:mm:ss,SSS]} [%5p] [%c:%L] - %m%n
 
### Save exception information to a separate file ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = D:/logs/errorSalary.log ## Exception log file name
log4j.appender.D.Append = true
log4j.appender.D.Threshold = ERROR   ## Output DEBUG Log above level
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern =  %d{[yyyy/MM/dd HH:mm:ss,SSS]} [%5p] [%c:%L] - %m%n

java To configure
/**
* Log Support for   Need to call log4j Configured classes
*/
protected Log log = LoggerUtil.newLogger(getClass());
 
public final class LoggerUtil {
 
/**
* initialization Logger class
*/
@SuppressWarnings("unchecked")
public static final Log newLogger(Class className) {
        Logger logger = Logger.getLogger(className);
 
        Log4JLogger log = new Log4JLogger(logger);
 
    return log;
    }
}
  // test class
 public   class  TestLog4j  {
     public   static   void  main(String[] args)  {
        PropertyConfigurator.configure( " D:/Code/conf/log4j.properties " );
        Logger logger  =  Logger.getLogger(TestLog4j. class );
        logger.debug( " debug " );
        logger.error( " error " );
    } 

pom The dependent jar package
<!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-log4j12 -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.8.0-beta2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/commons-logging/commons-logging -->
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.2</version>
        </dependency>