Create Web Service (SOAP or REST) using Struts2 and hibernate

Question

i have the problem when calling web service using struts 2 and hibernate...

HTTP Status 500 - Unable to instantiate Action, actions.events.rest.EventController, defined for 'event' in namespace '/'Error creating bean with name 'actions.events.rest.EventController': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [actions.events.rest.EventController]: Constructor threw exception; nested exception is java.lang.NullPointerException

this is my source:

EventController :

public class EventController extends BaseAction implements ModelDriven<Object> {
private static final long serialVersionUID = 1L;
private String id;
private Object model; 

private static Map<String, Event> map;
{ 
    List<Event> events = services.getEvents();
    for(Event event : events){
        map.put(event.getId() + "", event);
    } 
}

public HttpHeaders index() {
    model = map;
    return new DefaultHttpHeaders("index").disableCaching();
}

public String add(){ 
    services.createEvent("Event1");
    return "SUCCESS";
}

public String getId() {
    return id;
}
public void setId(String id) {
    Integer iid = Integer.parseInt(id);
    model = services.getEventById(iid);
    this.id = id;
}

public Object getModel() {
    return model;
}

BaseAction:

public class BaseAction extends ActionSupport {
// So that spring can inject the business singleton
protected Services services;

public void setServices(Services value) {
    services=value;
}

// For redirect results
protected String redirectUrl;

public String getRedirectUrl() {
    return redirectUrl;
}

public String redirect(String to) {
    redirectUrl = to;
    return "redirect";
}

When I debug, I got error in List<Event> events = services.getEvents(); in EventController. What can it be ?

score 1 · Accepted Answer · edited May 23 '17 at 12:23

The exception is caused by the fact that
you're referencing to the injected bean services from within a static initialization block:
```
{ 
    List<Event> events = services.getEvents();
    for(Event event : events){
        map.put(event.getId() + "", event);
    } 
}
```
remove it completely, do this kind of things in a prepare() method, or in a @PostConstruct method, or wherever but leave static blocks alone.

That said, you are following some bad practices:

you're returning "SUCCESS" while it should be "success" or SUCCESS (that is "success")
you're putting logic in setters, and it's better not
I'd also suggest to drop ModelDriven, drop Spring at all and use CDI, but this last is my humble opinion. BTW, ensure to take a look at what I'm talking about.

Create Web Service (SOAP or REST) using Struts2 and hibernate

1 Answers1