Spring logging

Logging library to be used with Spring Framework. Contains two mechanisms:

• Logger injection
• Logging aspects

Logger injection

In order to inject a logger instance into a spring managed bean use @Log annotation.

Example usage:

	import org.slf4j.Logger;
	import org.springframework.stereotype.Component;

	@Component
	public class BeanWithLogger {
		
		@Log
		private Logger logger;

		@Log(fromClass = SomeOther.class)
		private Logger logger2;
		
		/* ... */
		
	}

Configuration

To enable logger injection with @Log, simply register LogInjector in spring context.

Example using spring-java-config:

	import org.springframework.logging.inject.LogInjector;
	import org.springframework.context.annotation.Bean;
	import org.springframework.context.annotation.Configuration;

	@Configuration
	public class LogInjectorConfiguration {
		@Bean
		public LogInjector logInjector() {
			return new LogInjector();
		}
	}

Logger aspects

In order to log method invocations with aspects use @Logged annotation. You can use this annotation on methods and classes.

Example usage:

	import org.slf4j.Logger;
	import org.springframework.stereotype.Component;

	@Component
	@Logged
	public class BeanWithAspectLogging {

		public void sayHello() {
			/* ... */
		}

		public void sayHello(String hello) {
			/* ... */
		}

		public String sayHelloAndThrowNullPointerException(String hello) {
			logger.info("Inside method sayHelloReturnException. Hello: {}", hello);
			throw new NullPointerException("Test exception");
		}

	}

Configuration

To enable aspect logging just register LoggedAspect in spring context.

Example using spring-java-config:

	import org.springframework.logging.aspect.LoggedAspect;
	import org.springframework.context.annotation.Bean;
	import org.springframework.context.annotation.Configuration;
	import org.springframework.context.annotation.EnableAspectJAutoProxy;

	@Configuration
	@EnableAspectJAutoProxy(proxyTargetClass = true)
	public class LoggedAspectConfiguration {

		@Bean
		public LoggedAspect loggedAspect() {
			return new LoggedAspect();
		}

	}

Console output

Default console output for BeanWithAspectLogging#sayHelloAndThrowNullPointerException(String hello):

	2013-09-04 11:43:24,561 [TRACE] o.s.u.l.a.b.BeanTypeAnnotated:118 - >>> BeanTypeAnnotated.sayHelloReturnException(..): [xxx]
	/* Logs printed during method invocation */
	2013-09-04 11:43:24,582 [ERROR] o.s.u.l.a.b.BeanTypeAnnotated:134 - XXX Error occured: 
	/* Exception stack trace */
	2013-09-04 11:41:30,448 [TRACE] o.s.u.l.a.b.BeanTypeAnnotated:140 - <<< Returning BeanWithAspectLogging.sayHelloAndThrowNullPointerException(): null (14[ms])

Default console output can be overriden with custom implementation of MessageFormatter. Default logger provider mechanism can be overriden with custom implementation of LoggerProvider.

Maven dependency

In order to use this library add repository location into your pom.xml and add appropriate dependency.

	<dependency>
		<groupId>net.exacode.spring.logging</groupId>
		<artifactId>spring-aspect</artifactId>
		<version>${version.spring-logging}</version>
	</dependency>
	<!-- or -->
	<dependency>
		<groupId>net.exacode.spring.logging</groupId>
		<artifactId>spring-inject</artifactId>
		<version>${version.spring-logging}</version>
	</dependency>