Spring Cloud Spring Boot mybatis Distributed Microservice Cloud Architecture (38) Use log4j to record logs

Introduce log4j dependencies

When creating the Spring Boot project, we introduced spring-boot-starter, which includes spring-boot-starter-logging, the dependency content is Logback, the default logging framework of Spring Boot, so before we introduce log4j, we need to exclude the dependency of this package, and then introduce the dependency of log4j, like Here's what it looks like:

<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>

Configure log4j.properties

After the log4j dependency is introduced, you only need src/main/resourcesto add log4j.propertiesa configuration file to the directory to start configuring and using the application's logs.

console output

Through the following configuration, set the output level of the root log to INFO, and the appender to output stdout to the console

# LOG4J配置
log4j.rootCategory=INFO, stdout

# 控制台输出
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,SSS} %5p %c{1}:%L - %m%n

output to file

In the development environment, we just output to the console without a problem, but in the production or test environment, the log content may be persisted to facilitate tracing the cause of the problem. You can output to different files by day by adding the following appender content, and you also need to log4j.rootCategoryadd an appender named file, so that the root log can be output to the logs/all.logfile.

#
log4j.rootCategory=INFO, stdout, file

# root日志输出
log4j.appender.file=org.apache.log4j.DailyRollingFileAppender
log4j.appender.file.file=logs/all.log
log4j.appender.file.DatePattern='.'yyyy-MM-dd
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} %5p %c{1}:%L - %m%n

Classification output

When we have a large amount of logs, it will be very difficult to find the problem. The common method is to classify the logs, such as:

• You can output by different packages. By defining the output to logs/my.logthe appender, and com.didispacesetting the log level under the package to the DEBUG level, the appender is set to the output to logs/my.logthe named didifileappender.

  # com.didispace包下的日志配置
  log4j.category.com.didispace=DEBUG, didifile
  
  # com.didispace下的日志输出
  log4j.appender.didifile=org.apache.log4j.DailyRollingFileAppender
  log4j.appender.didifile.file=logs/my.log
  log4j.appender.didifile.DatePattern='.'yyyy-MM-dd
  log4j.appender.didifile.layout=org.apache.log4j.PatternLayout
  log4j.appender.didifile.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} %5p %c{1}:%L ---- %m%n
  

   

• Different levels can be classified, such as outputting the ERROR level to a specific log file. The specific configuration can be as follows.

  
  log4j.logger.error=errorfile
  # error日志输出
  log4j.appender.errorfile=org.apache.log4j.DailyRollingFileAppender
  log4j.appender.errorfile.file=logs/error.log
  log4j.appender.errorfile.DatePattern='.'yyyy-MM-dd
  log4j.appender.errorfile.Threshold = ERROR
  log4j.appender.errorfile.layout=org.apache.log4j.PatternLayout
  log4j.appender.errorfile.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} %5p %c{1}:%L - %m%n
  

  This article mainly introduces how to introduce log4j in spring boot, as well as some basic usage.

• source code