Spring之通过注解配置Bean

对于扫描到的组件，Spring有默认的命名策略，即第一个字母小写，也可以在注解中通过value属性值标识组件的名称

①第一个注解@Component

import org.springframework.stereotype.Component;

@Component
public class TestObject {

}

②第二个注解@Controller

import org.springframework.stereotype.Controller;

//模拟表现层
@Controller
public class UserController {

    public void execute(){
        System.out.println("usercontroller execute...");
    }
}

③第三个注解@Repository

public interface UserRepository {
    public void save();
}

import org.springframework.stereotype.Repository;
//模拟表现层
@Repository("userRepository")
public class UserRepositoryImpl implements UserRepository {

    @Override
    public void save() {
        // TODO Auto-generated method stub
        System.out.println("UserRepository save");
    }

}

<?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-3.1.xsd">

    <!-- 指定Spring IOC容器扫描的包 --> 
    <!-- 
        可以根据resource-pattern来指定扫描的资源
        resource-pattern="resposotory/*.class"
     -->
     <!-- 
         context:exclude-filter  不包含
      -->
      <!-- 
    <context:component-scan base-package="com.auguigu.spring.beans.annotation">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
    </context:component-scan>
     -->
     <!-- context:include-filter  包含    还得将默认的过滤器关掉-->
    <context:component-scan base-package="com.auguigu.spring.beans.annotation" use-default-filters="false">
        <context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
    </context:component-scan>
</beans>

base-package属性指定一个需要扫描的基类包

如果仅希望扫描特定的类而非基包下的所有类，可使用 resource-pattern 属性过滤特定的类，示例：

<context:component-scan base-package="com.atguigu.spring"

   resource-pattern="repository/*.class"></context:component-scan>

@Component: 基本注解, 标识了一个受 Spring 管理的组件
@Respository: 标识持久层组件
@Service: 标识服务层(业务层)组件
@Controller: 标识表现层组件

测试Main

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.auguigu.spring.beans.annotation.controller.UserController;
import com.auguigu.spring.beans.annotation.repository.UserRepository;

public class Main {
    
    public static void main(String[] args) {
        
        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");
        TestObject testObject = (TestObject) ctx.getBean("testObject");
        System.out.println(testObject);
        
        UserController uc = (UserController) ctx.getBean("userController");
        System.out.println(uc);
        
        UserRepository ur = (UserRepository) ctx.getBean("userRepository");
        System.out.println(ur);
    }

}

如果需要在一个类中引用另一类，@Autowired 将会在IOC容器中自动装配所需要的bean

@Autowired
    private UserRepository userRepository;
    public void add(){
        userRepository.save();
        System.out.println("userService add");
    }