we are developing an application. The application will be deployed in a proprietary event processing engine. We are not supposed to use any api such as spring core for DI. There are not proprietary DI frameworks yet. So the idea is to write one and a simple one.
Can any one please provide some inputs.
My idea is to write a factory class which has static methods in it. The static methods will return instances of the classes we want. For now we only want a single instance. I am assuming the below kind of code
public final class MyFactory {
private static ClassA classA = new ClassA();
private static ClassB classB = new ClassB();
private MyFactory() {
throw new CustomException("Cannot create instance");
}
public static ClassA getClassAInstance() {
return classA;
}
public static ClassB getClassBInstance() {
return classB;
}
}
Later I will use it like this
public class SomeRandomClass {
private ClassA classA = MyFactory.getClassAInstance();
}
Other thing I see is I need not test ClassA and ClassB. Testing SomeRandomClass will cover ClassA and ClassB. Because static content is always loaded first. So while testing SomeRandomClass I always have ClassA instance in it. So writing a junit on some method in SomeRandomClass will invoke methods in ClassA. Is this good?
Is it the right way I am doing? Can I improve it even?
forNameon a string value somewhere. What specific requirements do you really have?MyFactoryis called the Service Locator pattern; it is considered to be an anti-pattern. You should use constructor injection instead.