SLF4J ANNOTATION HOW TO

Other examples of error logs are database connection failures and configuration errors. Exceptions are considered ERROR level logs. SLF4J provides 5 default logging levels in Spring boot:ĮRROR - Error logs are serious issues that affect a significant part of the system or some part of your application has failed to operate. If there's a huge error going on, you don't want it to be cluttered by a bunch of working, low-level INFO logs! These logs have different levels of urgency, and distinction between them using log levels is important for filtering out logs that don't have to be output depending on the circumstance. The first log is a general informative type of message while the second log is a NullPointerException message. NullPointerException: id of User is null.Successfully updated User information: Updated name John to Jon.Logging levels allows distinction between the following sample logs:

For example, Hibernate SQL queries are categorized as DEBUG, which is a low-urgency log level that is mainly invoked for debugging purposes. Log Levels in Spring BootĪs mentioned before, logging in Spring Boot comprises different levels. This brings us to an important topic - log levels, which deserve an explanation of their own. If the log level was set to ERROR, then only the error message would be displayed since it's the highest log level of the 5 built-in levels. The DEBUG and TRACE messages weren't displayed because the application's log level is set to INFO, which has a higher priority level than the two. So if we were to call the method logLevelDisplay(), it would output something like this: 12:46:35.880 ERROR 47958 - c.service.DemoService : Error message If no configurations are set in application.properties or elsewhere, the log level will default to INFO. To enable logging in Spring, import Logger and LoggerFactory from the org.slf4j API library: import

SLF4J ANNOTATION HOW TO

In this tutorial, we'll take a look at how to perform Logging in Spring Boot, using SLF4J, as well as log levels and the configuration required to customize them, and log groups. Each log entry also includes an identifier called a logging level. Each log entry contains information such as the timestamp, the actual method being called, a custom log message, and other contextual information. Additionally, by default you can use any of the logging frameworks under the SLF4J API such as Logback (which is the default), Log4J2, and Java Util Logging in Spring Boot.Īpplication logging is a powerful development tool that is important for production-level support and debugging. Spring Boot makes use of Apache Commons' Logging for its system logs by default. Server logs are an important part of development that record the activities or events that the system is performing at any given point in time.

Slf4j annotation