예제 4-1 초기화 콜백 메서드가 정의된 Singer 클래스([[bean-init-method]] Singer.java)

package com.apress.prospring5.ch4;

import org.springframework.beans.factory.BeanCreationException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;

public class Singer {
    private static final String DEFAULT_NAME = "Eric Clapton";

    private String name;
    private int age = Integer.MIN_VALUE;

    public void setName(String name) {
        this.name = name;
    }

    public void setAge(int age) {
        this.age = age;
    }

    private void init() {
        System.out.println("빈 초기화");

        if (name == null) {
            System.out.println("기본 이름 사용");
            name = DEFAULT_NAME;
        }

        if (age == Integer.MIN_VALUE) {
            throw new IllegalArgumentException(
                    Singer.class +" 빈 타입에는 반드시 age 프로퍼티를 설정해야 합니다.");
        }
    }

    public String toString() {
        return "\t이름: " + name + "\n\t나이: " + age;
    }

    public static void main(String... args) {
        GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
        ctx.load("classpath:spring/app-context-xml.xml");
        ctx.refresh();

        getBean("singerOne", ctx);
        getBean("singerTwo", ctx);
        getBean("singerThree", ctx);

        ctx.close();
    }

    public static Singer getBean(String beanName, ApplicationContext ctx) {
        try {
            Singer bean = (Singer) ctx.getBean(beanName);
            System.out.println(bean);
            return bean;
        } catch (BeanCreationException ex) {
            System.out.println("빈 구성 도중 에러 발생: "
                    + ex.getMessage());
            return null;
        }
    }
}