I. Introduction of related packages and dependencies

I use the method of slf4j+log4j to introduce pom files. There is another method of Commons logging + log4j. I will not talk about it here. You can refer to the materials you need.

    <!--slf4j+log4j-->
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
      <version>1.7.25</version>
    </dependency>

II. Configure log4j.properties file

About the configuration of log4j.properties configuration file, I only post my own configuration here:

#//Be careful not to change the name with INFO, DEBUG, etc
log4j.rootLogger=infoA,errorA,stdout,DEBUGA

#Filtering out the extra logs under the spring framework
log4j.category.org.springframework = WARN

#Output to console
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.Threshold = debug
log4j.appender.stdout.layout.ConversionPattern=%d %-5p %c{1}:%L - %m%n

#Output error to specified file
log4j.logger.errorA=error
log4j.appender.errorA=org.apache.log4j.DailyRollingFileAppender
log4j.appender.errorA.layout=org.apache.log4j.PatternLayout
log4j.appender.errorA.layout.ConversionPattern=%d{yyyy-MM-dd-HH-mm} [%t] [%c] [%p] - %m%n
log4j.appender.errorA.datePattern=yyyy-MM-dd'.log'
log4j.appender.errorA.Threshold = error
log4j.appender.errorA.append=true
log4j.appender.error.File=d:/log/error.log

#Output DEBUG information to the specified file
log4j.logger.DEBUGA=DEBUG
log4j.appender.DEBUGA=org.apache.log4j.DailyRollingFileAppender
log4j.appender.DEBUGA.layout=org.apache.log4j.PatternLayout
log4j.appender.DEBUGA.layout.ConversionPattern=%d{yyyy-MM-dd-HH-mm} [%t] [%c] [%p] - %m%n
log4j.appender.DEBUGA.datePattern=yyyy-MM-dd'.log'
log4j.appender.DEBUGA.Threshold = DEBUG
log4j.appender.DEBUGA.append=true
log4j.appender.DEBUGA.File=d:/log/debug_log.log

#Print sql statement
log4j.logger.com.ibatis=DEBUG
log4j.logger.java.sql.ResultSet=INFO
log4j.logger.com.ibatis.common.jdbc.SimpleDataSource=DEBUG
log4j.logger.com.ibatis.common.jdbc.ScriptRunner=DEBUG
log4j.logger.com.ibatis.sqlmap.engine.impl.SqlMapClientDelegate=DEBUG
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

3. Configure mybats-config.xml

The main function of configuring mybats-config.xml is to combine it with log4j and output sql logs in the console and files. For options on LogImpl, please refer to other materials.
 

<settings>
    <setting name="logImpl" value="LOG4J" />
</settings>

4. Write information to the log manually in the code

private static final Logger logger = org.apache.log4j.Logger.getLogger(User.class);

@RequestMapping("/login")
public String login() {
    logger.debug("start printing log ================);
    logger.info("info================");
    logger.debug("info================");
    System.out.println("syso================");
    return "login";
}

Launch the project, you can see that the log files and the console have printed the logs, and also filtered many logs under the unnecessary spring framework