Cannot Autowire Service in HandlerInterceptorAdapter

Question

I'm getting a `NullPointerException` when trying to `@Autowire` my `@Service`: ``` public class PagePopulationInterceptor extends HandlerInterceptorAdapter { private @Autowired MyService service; public @Override void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView mav) { service.savePageView(IPUtils.toLong(request.getRemoteAddr()), request.getRequestURI(), request.getHeader("User-Agent")); mav.addObject("counter", service.getCounter()); } } @Configuration @ComponentScan(basePackages = "com.mycompany", excludeFilters = { @ComponentScan.Filter(Configuration.class) }) @PropertySource("classpath:application.properties") @EnableTransactionManagement @EnableWebMvc public class MyConfig extends WebMvcConfigurerAdapter { public @Override void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(new PagePopulationInterceptor()); } } @Service @Transactional public class MyService { private @Autowired PageViewDao pageViewDao;…

Accepted Answer

That's because Spring isn't managing your `PagePopulationInterceptor` instance. You are creating it yourself in the below code

```
public @Override void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(new PagePopulationInterceptor());
}
```

change that to

```
@Bean
public PagePopulationInterceptor pagePopulationInterceptor() {
    return new PagePopulationInterceptor();
}

public @Override void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(pagePopulationInterceptor());
}
```

In this way, Spring will manage the lifecycle of the `PagePopulationInterceptor` instance since it's generated from a `@Bean` method. Spring will scan it for `@Autowired` targets and inject them.

This assumes that `PagePopulationInterceptor` is in a package to be `@ComponentScan`ed.

Cannot Autowire Service in HandlerInterceptorAdapter

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