解读@NoArgsConstructor,@AllArgsConstructor,@RequiredArgsConstructor的区别及在springboot常用地方

@AllArgsConstructor
public class demo {

    private String name;

    // 被final修饰
    private final String age;

    @NonNull
    private String sex;
}

public class demo
{
	// 默认 只要是该类下的字段，无论什么修饰，都会被参与构造
    public demo(String name, String age, String sex)
    {
        if(sex == null)
        {
            throw new NullPointerException("sex is marked non-null but is null");
        } else
        {
            this.name = name;
            this.age = age;
            this.sex = sex;
            return;
        }
    }

    private String name;
    private final String age;
    private String sex;
}

@RequiredArgsConstructor
public class demo {

    private String name;

    // 被final修饰
    private final String age;

    @NonNull
    private String sex;
}

public class demo
{
	// 只构造了有final或者no-null修饰的字段
    public demo(String age, String sex)
    {
        if(sex == null)
        {
            throw new NullPointerException("sex is marked non-null but is null");
        } else
        {
            this.age = age;
            this.sex = sex;
            return;
        }
    }

    private String name;
    private final String age;
    private String sex;
}

@Component
public class BeanTest1 {
}

@Component
public class BeanTest2 {
}

@Component
public class BeanTest3 {
}

@Component
@AllArgsConstructor
@ToString
public class ConstructorDemo {
	// 注入三个bean对象，完全没有使用Autowired注解
    private BeanTest1 beanTest1;

    @NonNull
    private BeanTest2 beanTest2;

    private final BeanTest3 beanTest3;
}

// 这只是个测试类
@Component
public class ConstructorRunner implements ApplicationRunner {

    @Autowired
   ConstructorDemo ConstructorDemo;

    @Override
    public void run(ApplicationArguments args) throws Exception {
        System.out.println(ConstructorDemo);
    }
}

// 改成@RequiredArgsConstructor
@Component
@RequiredArgsConstructor
@ToString
public class ConstructorDemo {

    private BeanTest1 beanTest1;

    @NonNull
    private BeanTest2 beanTest2;

    private final BeanTest3 beanTest3;
}

@Component
@ToString
public class ConstructorDemo {

    private BeanTest1 beanTest1;

    @NonNull
    private BeanTest2 beanTest2;

    private BeanTest3 beanTest3;

    @Value("${constructor.name:hello}")
    private String name;
    
}

@Component
@ToString
@AllArgsConstructor
public class ConstructorDemo {

    private BeanTest1 beanTest1;

    @NonNull
    private BeanTest2 beanTest2;

    private BeanTest3 beanTest3;

    @Value("${constructor.name:hello}")
    private String name;
}

@Component
@ToString
@RequiredArgsConstructor
public class ConstructorDemo {
	// 肯定为null，因为没有final或者no-null修饰
    private BeanTest1 beanTest1;

    @NonNull
    private BeanTest2 beanTest2;

    private final BeanTest3 beanTest3;

    @Value("${constructor.name:hello}")
    private String name;
}