Using Spring Scheduler to return rows from DB throws Null pointer Exception - spring

Question

I am using Spring scheduling to schedule a task that performs some DB operation every hour. This throws a NullPointerException every time I try to call a function that triggers DB specific operations.
Configuration File :
#Configuration
#EnableWebMvc
#ComponentScan(basePackages="com.bt.rtddashboard")
/*#EnableJpaRepositories(basePackages = {
"com.bt.rtddashboard"
})*/
#EnableScheduling
#PropertySource("classpath:jdbc.properties")
public class RTDDashboardConfiguration extends WebMvcConfigurerAdapter {
#Resource
private Environment env;
#Bean(name = "dataSource", destroyMethod="close")
public DataSource getDataSource() {
//DB code
}
private Properties getHibernateProperties() {
//Hibernate code
}
#Bean(name = "sessionFactory")
#Scope("singleton")
public LocalSessionFactoryBean getSessionFactory() {
}
#Autowired
#Bean(name = "transactionManager")
public HibernateTransactionManager getHibernateTransactionManager(SessionFactory factory) {
;
}
public void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("/**").addResourceLocations("/").setCachePeriod(31556926);
}
#Scheduled(fixedRate=1000)
public void work() {
// task execution logic
System.out.println("Scheduled Task");
DashboardController controller=new DashboardController();
controller.performTask();
}
}
Dashboard Controller :
#RestController
public class DashboardController {
#Autowired
private InlineService service;
#RequestMapping(value="/rtd/getAllServers", method=RequestMethod.GET)
public ResponseEntity<List<ServerMonitor>> getAllServers(){
List<ServerMonitor> ilsList=new ArrayList<ServerMonitor>();
ResponseEntity<List<ServerMonitor>> response=null;
try{
ilsList=service.getAllServers();
response=new ResponseEntity<List<ServerMonitor>>(ilsList,HttpStatus.OK);
System.out.println("Scheduled Time");
}catch(Exception e){
}
return response;
}
public void performTask(){
System.out.println("Scheduled Task Starts in Contrroller");
List<IlsStats> ilsStats =new ArrayList<IlsStats>();
List<IlsStatsHistory> ilsStatsHisList=new ArrayList<IlsStatsHistory>();
try{
//get All the ILS Stats
ilsStats=service.getAllInlineStats();
System.out.println("No of rows to Copy : " + ilsStats.size());
ilsStatsHisList=formILSHistoryList(ilsStats);
int flag=service.insertInIlsStatsHistory(ilsStatsHisList);
//List<ServerMonitor> ilsList=service.getAllServers();
}catch(Exception e){
e.printStackTrace();
}
}
Here, ilsStats=service.getAllInlineStats(); throws NullPointerException.
Even though the rest webservice created on top of it is working fine.
Stack Trace :
Scheduled Task
Scheduled Task Starts in Contrroller
java.lang.NullPointerException
at com.bt.rtddashboard.controller.DashboardController.performTask(DashboardController.java:226)
at com.bt.rtddashboard.configuration.RTDDashboardConfiguration.work(RTDDashboardConfiguration.java:137)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65)
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:304)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
The same stack trace comes up every 1 sec now.

Answer 1

Creating an #Scheduled method in a configuration class is a very bad idea (imho). Next to that I also think that having a scheduler calling a controller method (a method tied to a web related component!) is generally a bad idea/design.
Nonetheless the problem is that you do new DashboardController(). That will obviously create a bean outside the scope of spring and will never be dependency injected. Instead inject the into the class and use that instance.
#Autowired
private DashboardController controller;
#Scheduled(fixedRate=1000)
public void work() {
controller.performTask();
}
Or even better just remove that method all together and simply place #Scheduled(fixedRate=1000) on the performTask method instead.