Log Levels

Elements of Logging Framework

Logger: It captures the messages. Formatter: It formats the messages which are captured by loggers. Handler: It prints messages on the console, stores them in a file or sends an email, etc....

Log Levels

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0. Default Logging With No Configurations

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Logging to a file

Spring boot allows us to see the logs in the console even if we do not provide any specific configuration for it. This is because spring boot uses Logback for its default logging. Spring boot’s internal logging provider is Apache Commons which provides support for Java Util Logging ,Log4j2, and Logback. Hence Apache Commons had to be manually imported until spring boot 1.x. However, since spring boot 2.x, it is downloaded transitively. To be more specific, Spring boot starters such as spring-boot-starter-web imports spring-boot-starter-logging which automatically pulls in Logback. On running the application and visiting the http://localhost:8080/log page, we can see the following output in the console:...

1. Logging with Logback configuration

Spring boot only logs to the console by default. In order to log into a file, the following properties need to be added to the application.properties file:...

2. Logging with Log4j2 configuration

Spring boot enables logback to be configured in a specific manner to meet our project’s requirements. In order to do so, we need to define a configuration file where we can specify logging pattern, color, different properties for file logging & console logging, and an efficient rolling policy to prevent the creation of huge log files. Whenever Spring boot finds a file with any of the following names, It automatically overrides the default configuration....

3. Logging with Lombok

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4. @Slf4j and @CommonsLog

For using log4j2, we need to exclude Logback from our starter dependency and add the dependency for log4j2 as follows:...