11.2.1Filter Hook Interceptors
A filter hook is a hook that wraps a supplied function (i.e. Supplier). Filter hooks allow implementers to run custom code around the supplied function's execution (similar to Java Servlet Filters). Implementers can specify logic that should be executed:
-
Before the supplied function call is made
-
When the supplied function call throws an exception
-
After the supplied function call is made
The example below shows how a Filter Hook Interceptor can be implemented with the BATCH2_CHUNK_PROCESS_FILTER pointcut:
import ca.uhn.fhir.batch2.model.JobInstance;
import ca.uhn.fhir.batch2.model.WorkChunk;
import ca.uhn.fhir.interceptor.api.Hook;
import ca.uhn.fhir.interceptor.api.IBaseInterceptorBroadcaster.IInterceptorFilterHook;
import ca.uhn.fhir.interceptor.api.Pointcut;
public class WorkChunkProcessingInterceptor {
@Hook(Pointcut.BATCH2_CHUNK_PROCESS_FILTER)
public IInterceptorFilterHook batch2ProcessFilter(JobInstance theJobInstance, WorkChunk theWorkChunk) {
return theContinuation -> {
try {
// Perform pre-processing logic before the work chunk is processed
// Process the work chunk (Note: If the continuation is not ran, an IllegalStateException will be
// thrown)
theContinuation.run();
} catch (Exception e) {
// Handle any exceptions that occur during work chunk processing
// rethrow the exception
throw e;
} finally {
// Perform any necessary cleanup or final operations
}
};
}
}