java - How can Spring instantiate cClasses with private constructors (singleton pattern) and objects from Factories? -

i studying spring core certification , have following doubt related how can spring instantiate classes private constructors (such singleton pattern) or how can instantiate objects factories (that not spring context).

for example have following singleton factory:

public class accountservicesingleton implements accountservice {      private static accountservicesingleton inst = new accountservicesingleton();      private accountservicesingleton() { ... }      public static accountservice getinstance() {         // ...         return inst;     } } 

this singleton factory because build private static object builded private constructor , have public method object.

so think problem how can spring build object? depends on fact that constructor private can't in java configuration class

@confguration public class applicationconfig{      @bean     public accountservicesingleton accountservicesingleton(){         return new accountservicesingleton();     } } 

because can't access private accountservicesingleton() constructor.

at same time can't use equivalent xml configuration same reason.

have understand problem or missing something?

i think missing because on documentation read can use following 2 solutions previous problem:

1. use @bean method in @configuration class: so, reading it, think previous java configuration class work...but why?

2. xml factory-method attribute in xml configuration, searching online found have this, how can use configure previous accountservicesingleton bean in xml configuration?

tnx

it's easy, , can it, too:

constructor cxor = accountservicesingleton.class.getdeclaredconstructor(); cxor.setaccessible(true); return cxor.newinstance();