Spring日志和用户定义的日志分离

Question

I am building a Spring boot project with Tomcat server where in Spring automatically takes care of all the logging mechanism, all the logs are present in "catalina.out" file.

Now that, I have a requirement where I need to log only specific information to a separate log file.

I have done the below configuration, but now all the logs including the main logs are appending in the same file.

I need only specific logs into a separate log file.

Can anyone suggest me a solution for this?

My pom.xml looks like this.

 <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-logging</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-log4j</artifactId>
    </dependency>

My log4j.properties look like this.

# Root logger option
log4j.rootLogger=INFO,file

# Direct log messages to a log file
log4j.appender.file=org.apache.log4j.RollingFileAppender

#Redirect to Tomcat logs folder
#log4j.appender.file.File=${catalina.home}/logs/logging.log

log4j.appender.file.File=/my_log.log
log4j.appender.file.Append=true
log4j.appender.file.MaxFileSize=10MB
log4j.appender.file.MaxBackupIndex=10
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

The java file looks like this.

static org.apache.log4j.Logger log4jLogger = org.apache.log4j.Logger.getLogger(MyClass.class.getName());

log4jLogger.info("My specific logs here");

Answer 1

According to FAQ Logging , the CATALINA_BASE/logs/catalina.out contains the output of System.out and System.err .

Therefore, you need to redirect the output of Spring to System.out . That can be done using org.apache.log4j.ConsoleAppender .

Using this appender, your configuration file may be similar:

# Root logger option
log4j.rootLogger=info, stdout

# Direct log messages to the console
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

# Direct log messages to a log file
log4j.appender.file=org.apache.log4j.RollingFileAppender
log4j.appender.file.File=/my_log.log
log4j.appender.file.Append=true
log4j.appender.file.MaxFileSize=10MB
log4j.appender.file.MaxBackupIndex=10
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

# Output to the file only from certain packages (e.g. your application)
log4j.logger.com.foo=trace, file
log4j.logger.org.company=trace, file

If you do not want that your application also log to stdout , use:

# Output to the file only from certain packages (e.g. your application)
log4j.logger.com.foo=trace, file
log4j.additivity.com.foo=false
log4j.logger.org.company=trace, file
log4j.additivity.org.company=false

See more in Short introduction to log4j on Apache log4j 1.2 webpage.

---

Notes

1. Log4j Tutorial: Additivity – what and why?

Answer 2

You should create multiple loggers that point to different files (now you have just one, that why all ends in one file). Then you can distinguish the loggers with some prefix to the package. Something like

log4j.logger.file1.com.spring.something=.../define the logger
log4j.logger.file2.com.spring.somethingelse=.../second logger

and then when obtaining the logger use something like

org.apache.log4j.Logger.getLogger("file1" + MyClass.class.getName());