Spring study notes ten

Spring uses annotation Annotation to define Bean

1. UserDao interface and implementation class

public interface UserDao {
    void save();
}


@Component("userDao")
public class UserDaoImpl implements UserDao {
    public void save() {
        System.out.println("user dao save...");
    }
}

2. SpringConfig class

@Configuration
@ComponentScan("com.itheima")
public class SpringConfig {
}

3. How to use

public static void main(String[] args) {
        ApplicationContext ctx = new AnnotationConfigApplicationContext(SpringConfig.class);
        UserDao userDao = ctx.getBean("userDao", UserDao.class);
        System.out.println(userDao);
        userDao.save();
    }

4. Summary

• Using annotations to develop beans no longer requires some xml configuration files
• The @Configuration annotation in the SpringConfig class indicates that this class is a configuration class
• @ComponentScan is the scan directory of the Bean, which means looking for the Bean entity class in the com.itheima directory