如何@autowire一些bean进入JsonSerializer？

Question

I am using lazy loading with hibernate in my web app.

I would like to load some objects from the database at the parsing stage of the server response

 @Component public class DesignSerializer extends JsonSerializer<Design> { @Autowired IDesignService designService; <-- is null 

}

Which is totally understandable because DesignSerializer is being instantiated with the "new" operator for each object.

I am sure there is a way to inject my bean into that serializer when ever it is created, I just don't know how.

Can you guys help me or point me in the right direction.

Answer 1

Solution is SpringBeanAutowiringSupport if you are using Spring Framework 2.5+.

public class DesignSerializer extends JsonSerializer<Design> {

    @Autowired
        IDesignService designService;
    }

    public DesignSerializer(){
        SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);    
    }

...

}

I Hope that help you

Answer 2

We had the same problem with JsonSerializer and Spring autowiring. The solution that worked for us was to make two constructors. One for Spring which sets the dependency as a static field, and another one that is used by the Jackson initialisation.

This works because the Spring dependency injection (autowiring) happens before Jackson initialises the serializer.

@Component
public class MyCustomSerializer extends JsonSerializer<String> {

    private static IDesignService designService;

    // Required by Jackson annotation to instantiate the serializer
    public MyCustomSerializer() { }

    @Autowired
    public MyCustomSerializer(IDesignService designService) {
        this.designService = designService;
    }

    @Override
    public void serialize(String m, JsonGenerator gen, SerializerProvider s) {
        gen.writeObject(MyCustomSerializer.designService.method(..));
    }
}

Answer 3

I Solved the problem by creating a static field in a different bean and then @Autowire its setter method.

@Service("ToolBox")
@Transactional
public class ToolBox 
{
static Logger logger = Logger.getLogger(ToolBox.class);


private static IService service;


@Autowired
public void setService(IService service)
{
    ToolBox.service = service;
}

public static IService getService()
{
    return ToolBox.service;
}}

like shown in this thread: Can you use @Autowired with static fields?