SpringBoot 配置类 @Bean 例子

在Spring中 我们可以通过依赖注入 完成类之间的通信， SpringBoot则可以通过配置类 来实现我们所需要的功能。

我们以Service 调用 Dao 来做例子

//配置类
@Configuration
public class AppConfig {
   @Bean //通过@bean来实现<bean>的功能
   public StudentService studentService() {   //等价<bean id="">
	   StudentService stuService= new StudentService();
	   StudentDao studentDao= new StudentDao();
	   stuService.setStudentDao(studentDao);
	    return stuService;        //返回值 等价<bean class="">
   }
   @Bean StudentDao studentDao() {
	   StudentDao stuDao= new StudentDao();
	   return stuDao;
   }
   
}

Service

@Component
public class StudentService {

private static StudentDao studentdao;

public StudentService() {
	
}

public StudentDao getStudentDao() {
	return studentdao;
}

public void setStudentDao(StudentDao dao) {
	this.studentdao = dao;
}


@Test
	public void add() {
	 System.out.println("Service...");
      }
}

Dao

@Component
public class StudentDao {
	public StudentDao() {
		
	}
	@Test
    public void add() {
    	System.out.println("Dao........");
    }
    
}

测试

	@Test
	public void contextLoads() {
		//System.out.println(student1);
		StudentService service = new StudentService();
		//StudentDao dao = new StudentDao();
		//service.setStudentDao(dao);
	    service.add();
	    service.getStudentDao().add();
	}