jAlarms can also be configured to be used with AspectJ so that you can annotate methods or classes to enable them to send alarms whenever an unhandled RuntimeException occurs. The way you do this is to setup the AlarmAspect class with a reference to your AlarmSender, and then add this aspect to your AOP setup.
The easiest way to do this in an application is through Spring AOP, since you only need to add the AOP schema, and declare the AOP AspectJ Autoproxying mechanism. The configuration looks like this:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
<!-- This is to enable the autoproxying mechanism, so that any annotated beans will be proxied
(this is necessary for the AlarmAspect to work) -->
<aop:aspectj-autoproxy />
<bean id="alarmAspect" class="com.solab.alarms.aop.AlarmAspect">
<!-- If you only have one AlarmSender configured and it's called "alarmSender",
then you don't need to specify this -->
<property name="alarmSender" ref="alarmSender" />
<property name="message" value="This is the alarm message that precedes the exception" />
<!-- You can set this to 0 to omit the stack trace, -1 to include the full stack trace,
or any other number to only include that number of lines of stack trace. -->
<property name="includeStackTrace" value="2" />
</bean>
</beans>
After that, you can use the @AlarmOnException annotation on a class or method and if a RuntimeException is thrown that the method does not handle, an alarm will be sent. The annotation has some properties, all of them optional.
@AlarmOnException(message="This is the alarm message", source="some-src", stack=5)
public class MyClass {
public void doSomething() {
//If an exception is thrown here, an alarm is sent
}
public void doSomethingElse() {
//An exception thrown here also sends an alarm.
}
}
public class AnotherClass {
public void doSomething() {
//No alarm is sent here
}
@AlarmOnException
public void doSomethingElse() {
//An alarm is sent in case of an exception, with the message that
//was configured in the aspect, no source, and the number of
//stack trace lines configured in the aspect.
}
}
IMPORTANT Note about proxying: If you annotate methods that are declared in an interface, then a JDK dynamic proxy can be used. If you annotate a class that implements an interface (or two or more), then only the methods declared in those interfaces will send alarm in case of an exception. If you want all of the methods to be adviced by the aspect, or you want to annotate a method that is not declared in any interface, then you need to use CGLIB proxies. If you want to use CGLIB proxies by default, you can add the proxy-target-class="true" attribute to the aop:aspectj-autoproxy entry in your Spring config.