Spring-Boot Access object created in main from RequestMapping - spring-boot

Question

I am using spring-boot for implementing a REST server. Inside a function for request mapping, I have to create an object which is heavyweight, so for every REST call I have do it and it is slowing things down. Is it possible to create the object in main and access from the function?
#SpringBootApplication
public class MyClass{
public static void main(String[] args) {
/* I want to initialize the object here */
SpringApplication.run(MyClass.class, args);
}
}
#RestController
public class MyController {
#RequestMapping("/go/to/user/summary")
public Users[] getUsers(#RequestParam(value="length", defaultValue="10") int length) {
/* I want to use the object here */
}

Answer 1

You can create a bean in MyClass and then consume that bean in MyController. Spring will only create a single instance of the bean so you'll avoid the cost of creating it multiple times. Something like this:
#SpringBootApplication
public class MyClass {
public static void main(String[] args) {
SpringApplication.run(MyClass.class, args);
}
#Bean
public Heavyweight heavyweight() {
// Initialize and return heavyweight object here
}
}
#RestController
public class MyController {
private final Heavyweight heavyweight;
#Autowired
public MyController(Heavyweight heavyweight) {
this.heavyweight = heavyweight;
}
#RequestMapping("/go/to/user/summary")
public Users[] getUsers(#RequestParam(value="length", defaultValue="10") int length) {
// Use heavyweight here
this.heavyweight.foo();
// ...
return users;
}
}

Answer 2

I think You can use #Service for this approach. Service class is Singleton so if You create object inside it on startup application then You can use it requests in Your controllers class.
Example service:
#Service
public class MyService{
private MyLargeObject largeObject;
public MyLargeObject set(MyLargeObject largeObject){
this.largeObject = largeObject;
}
public MyLargeObject get(){
return largeObject;
}
}
Example controller:
#RestController
public class MyController{
#Inject
private MyService myService;
#RequestMapping("/go/to/user/summary")
public Users[] getUsers(#RequestParam(value="length", defaultValue="10") int length) {
MyLargeObject o = myService.get();
}
}
EDIT1:
If You want init Your largeObject directly in service You can use #PostConstruct annotation. For example:
#PostConstruct
public void init() {
// initialization Your object here
}