Note: This is a simple Java Project, but following this POC is applicable for both any kind of Java based application.
<dependency>
<groupId>log4j</groupId>
<artifactId>apache-log4j-extras</artifactId>
<version>1.2.17</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.9.4</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.9.4</version>
</dependency>
Note: Version may change
In build section, use the following plugin.
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>aspectj-maven-plugin</artifactId>
<version>1.7</version>
<configuration>
<complianceLevel>1.8</complianceLevel>
<source>1.8</source>
<target>1.8</target>
<showWeaveInfo>true</showWeaveInfo>
<verbose>true</verbose>
<Xlint>ignore</Xlint>
<encoding>UTF-8 </encoding>
</configuration>
<executions>
<execution>
<goals>
<!-- use this goal to weave all your main classes -->
<goal>compile</goal>
<!-- use this goal to weave all your test classes -->
<goal>test-compile</goal>
</goals>
</execution>
</executions>
</plugin>
Log4j
Here I will only demonstrate properties based configuration. For XML / Java based configuration, please refer to this Link.
log4j.rootLogger=INFO, loggerId
log4j.appender.loggerId=org.apache.log4j.FileAppender
log4j.appender.loggerId.layout=org.apache.log4j.PatternLayout
log4j.appender.loggerId.layout.ConversionPattern=%d [%t] %-5p (%F:%L) - %m%n
log4j.appender.loggerId.File=example.log
AOP
The codes in ExecutionInterceptor is actually doing the job of AOP. @Aspect introduces this class as the aspect.
The @Around annotation is the advice, which means the logic inside method annoted with @Around will be added before and after the method execution declared in annotation's execution.
@Aspect
public class ExecutionInterceptor {
private static final Logger LOGGER = Logger.getLogger(ExecutionInterceptor.class);
// @Around("@annotation(Audit)")
@Around("execution(public * *(..))")
public Object intercept(final ProceedingJoinPoint point) throws Throwable {
long start = System.currentTimeMillis();
System.out.println(point.toString());
Thread.sleep(2000);
long executionTime = System.currentTimeMillis() - start;
LOGGER.info(String.format("Executed in %s seconds", executionTime));
return point.proceed();
}
}
We have a method in AccountService class which matches the expression of advice defined in the @Around advice.
In main method, when we call the withdraw(int val) method from AccountService class, all the calls will be logged in the file defined in log4j configuration.