Bean管理（3）

2021-01-29 分类 Spring 作者 Nayuki ~3.15K 字

基于注解创建对象

Component
Service
Controller
Repository

引入aop依赖包
引入context命名空间
开启组件扫描

<beans xmlns:context="http://www.springframework.org/schema/context" 
       xsi:schemaLocation="http://www.springframework.org/schema/context 
       http://www.springframework.org/schema/context/spring-context.xsd">
    <context:component-scan base-package="service"></context:component-scan>
</beans>

创建UserService类

@Service	//或者@Component(value = "userService") 
public class UserService {
    public void show() {
        System.out.println("Nayuki");
    }
}

测试

1 2	UserService userService =context.getBean("userService", UserService.class); userService.show();

基于注解注入属性

Autowired：根据类型进行自动装配

创建UserDaoImpl类

@Repository
public class UserDaoImpl implements UserDao{
    @Override
    public void update() {
        System.out.println("Nayuki!");
    }
}

创建UserService类

@Service
public class UserService {
    @Autowired
    UserDao userDao;
    public void show() {
        System.out.println("Nayuki");
        userDao.update();
    }
}

Qualifier：根据名称注入，和Autowired一起用

创建UserDaoImpl类

@Repository(value = "userDaoImpl")
public class UserDaoImpl implements UserDao{
    @Override
    public void update() {
        System.out.println("Nayuki!");
    }
}

创建UserService类

@Service
public class UserService {
    @Autowired
    @Qualifier(value = "userDaoImpl")
    UserDao userDao;
    public void show() {
        System.out.println("Nayuki");
        userDao.update();
    }
}

Resource：根据类型和名称注入，不建议使用

创建UserDaoImpl类

@Repository(value = "userDaoImpl")
public class UserDaoImpl implements UserDao{
    @Override
    public void update() {
        System.out.println("Nayuki!");
    }
}

创建UserService类

@Service
public class UserService {
    @Resource(value = "userDaoImpl")
    UserDao userDao;
    public void show() {
        System.out.println("Nayuki");
        userDao.update();
    }
}

Value：注入普通类型

创建UserService类

@Service
public class UserService {
    @Value(value = "Nayuki")
    String name;
    @Value(value = "1")
    int id;
    public void show() {
        System.out.println(id+"."+name);
    }
}

完全注解开发

创建配置类SpringConfig

@Configuration
@ComponentScan(basePackages = {"service"})
public class SpringConfig {
}

创建UserService类

@Service
public class UserService {
    @Value(value = "Nayuki")
    String name;
    @Value(value = "1")
    int id;
    public void show() {
        System.out.println(id+"."+name);
    }
}

测试

@Test
public void testAdd(){
    ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
    UserService userService =context.getBean("userService", UserService.class);
    userService.show();
}