Develop an web application using AspectJ
and log4j2.
1.
First we have to add required jars in
WEB-INF/lib folder. The following jars are need to develop AspectJ with web application.
2.
Secondly we will create META-INF folder under
src folder.
3.
Next we will add aop.xml file under META-INF
folder like below structure.
4.
My requirement is I want to log each and every public
method entrance and exit inside my project.
5.
For this we need to create one aspect class and
one configuration file (aop.xml).
6.
AspectJ provides some annotations like @Before, @After, @AfterReturning, @AfterThrowing ,@Around,
@Pointcut
7.
Now we are using @Before
and @After. Here @Before defines before each and every public
method calling and @After defines each and
every public method after calling.
8.
Create a class for aspect .Here I am creating LogAspect.java
LogAspect.java
@Aspect
public class LogAspect {
private static Logger logger = LogManager.getLogger(LogAspect.class);
@Pointcut("execution(public
* *.*(..))")
public void defineEntryPoint() {
}
@Before("defineEntryPoint()")
public void
beforeMethod(JoinPoint joinPoint) {
// System.out.println("Before"
+ joinPoint.getSignature());
logger.info("Before : " + joinPoint.getSignature());
}
@After("defineEntryPoint()")
public void
afterMethod(JoinPoint joinPoint) {
// System.out.println("After"
+ joinPoint.getSignature());
logger.info("After :" + joinPoint.getSignature());
}
}
9.
Now add aop.xml file. In this file we configure
LogAspect class and what are all the packages weave the AspectJ agent.
aop.xml
<!DOCTYPE aspectj
PUBLIC "-//AspectJ//DTD//EN"
"http://www.eclipse.org/aspectj/dtd/aspectj.dtd">
<aspectj>
<weaver>
<!-- only weave
classes in our application-specific packages -->
<include within="com.msr..*"
/>
</weaver>
<aspects>
<!-- weave in
just this aspect -->
<aspect name="com.msr.aspects.LogAspect"
/>
</aspects>
</aspectj>
10.
For testing purpose I am creating one servlet class.
Test.java
@WebServlet("/Test")
public class Test extends HttpServlet {
private static final long serialVersionUID = 1L;
public Test() {
super();
// TODO Auto-generated
constructor stub
}
protected void
doGet(HttpServletRequest request,
HttpServletResponse
response) throws ServletException,
IOException {
PrintWriter
out = null;
try {
out = response.getWriter();
Sample.mySample();
out.write("hello from
MyServlet");
}
catch (IOException e) {
e.printStackTrace();
}
finally {
if (out != null)
out.close();
}
}
}
Sample.java
public class Sample {
public static void mySample(){
System.out.println("this is my
sample method");
}
}
11. For logs where we have store which
pattern we have to store logs we have to configure in log4j2.xml file
Log4j2.xml
<?xml version="1.0"
encoding="UTF-8"?>
<Configuration status="warn"
complete="true">
<Appenders>
<Console name="Console"
target="SYSTEM_OUT">
<PatternLayout pattern="%d{HH:mm:ss.SSS}
[%t] %-5level %logger{36} -%l %msg%n
-%X{userName}%n" />
</Console>
</Appenders>
<Loggers>
<Root level="all"
additivity="false">
<AppenderRef ref="Console"
/>
</Root>
</Loggers>
</Configuration>
12.
Its important point now we have to configure
aspetjweaver agent. Aspectj given agent for this i.e apectjweaver-1.8.5.jar
in your class path and vm argument .
13.
If you are using eclipse for your application
development follow below steps.
Right click on your project ->
Run as -> Run configurations ->Arguments tab -> vm arguments inside this pass path your
aspectjweaver-1.8.5.jar.
14.
Run the web application and test using below url
.
The output comes like below.
16:53:02.378 [http-bio-1111-exec-3]
INFO
com.msr.aspects.LogAspect-com.msr.aspects.LogAspect.beforeMethod(LogAspect.java:25) – Before : void
com.msr.aspects.Sample.mySample()
-
this is my sample method
16:53:02.381 [http-bio-1111-exec-3]
INFO
com.msr.aspects.LogAspect-com.msr.aspects.LogAspect.afterMethod(LogAspect.java:31) – After : void
com.msr.aspects.Sample.mySample()
-
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