关于java:Spring-注解开发

注解开发

配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
<!--    扫描指定包下的注解-->
    <context:component-scan base-package="com.spring"/>
<!--    开启注解开发-->
    <context:annotation-config></context:annotation-config>

</beans>

POJO

@Component//作为组件注入bean 相似于<bean id="user" class="com.spring.pojo.User"/>
public class User {
    //值的注入相似于咱们的<property name="name" value="张三"></property>
    @Value("张三")
    private String name;
    public String getName() {
        return name;
    }
}

Dao

@Repository//注入默认为 Dao层对应三层架构的数据长久层
public class UserDao {
    private User user;
    @Autowired
    public UserDao(User user){
        this.user = user;
    }
    public void getName(){
        System.out.println(user.getName());
    }
}

Service

@Service//注入默认为 Service层对应三层架构的业务层
public class UserService {
    public UserDao userDao;
    @Autowired
    public UserService(UserDao userDao){
        this.userDao = userDao;
    }
    public void getName(){
        userDao.getName();
    }
}

Controller

@Controller//注入默认为 Controller层对应三层架构的管制层层
public class UserController {
    private UserService userService;
    @Autowired
    public UserController(UserService userService){
        this.userService=userService;
    }
    public void getName(){
        userService.getName();
    }
}

启动类

public class AnnotationTest {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("ApplicationContext.xml");
        UserController userDao = context.getBean("userController", UserController.class);
        userDao.getName();
    }
}

纯注解开发

配置文件

/**
* 表明该类是Spring的配置类
* 相似于咱们的xml文件
* 这个类也会交给Spring治理,@Configuration蕴含@Component注解
*/
@Configuration
/**
 * 包扫描相似于    <context:component-scan base-package="com.spring"/>
 */
@ComponentScan("com.spring")
/**
 * 导入另一个配置文件
 * 相似于 <import resource="springConfig2.xml"></import>
 */
@Import(SpringConfig2.class)
public class SpringConfig {
    /**
     * 相似于<bean></bean>
     * 注入了一个对象
     * 办法名是id属性
     * 办法返回值的类型是class属性
     */
    @Bean
    public User user(){
        return new User();
    }
}