How to create bean from stdin?-CodePudding

I got a requirement to create bean from stdin. I know how to create object via new keyword, but I don't know how to create bean from stdin by spring feature such as dependency injection. Any help please?

Object object;
Scanner scanner = new Scanner(System.in);
String input = scanner.nextLine();
if (input.startsWith("A")) {
     object = new A();
}
else if (input.startsWith("B")) {
     object = new B();
}

CodePudding user response：

You can use getBean() method of ApplicationContext class. But before that you need to declare class A and B as spring beans. Please refer below example: Class A

import org.springframework.stereotype.Component;

@Component //This annotation is used to declare this class as a bean
public class A {

    @Override
    public String toString() {
        return "A";
    }
}

Class B

import org.springframework.stereotype.Component;

@Component //This annotation is used to declare this class as a bean
public class A {

    @Override
    public String toString() {
        return "A";
    }
}

Now, you can use application context to create instances of above classes as shown in below example:

import java.util.Scanner;

import javax.annotation.PostConstruct;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Service;

@Service //Declares this call a service
public class StdinService {

    @Autowired //Injecting application context
    ApplicationContext applicationContext;

    @PostConstruct
    public void demo() {
        Object object = null;
        try (Scanner scanner = new Scanner(System.in)) {
            String input = scanner.nextLine();
            if (input.startsWith("A")) {
                object = applicationContext.getBean(A.class); //Usage of getBean method
            } else if (input.startsWith("B")) {
                object = applicationContext.getBean(B.class);
            }
        }

        System.out.println(object);
    }
}