Spring-IOC实现（自动注入）

自动注入

XML自动配置

XML自动配置通过四个注解实现，功能一样的

注解	描述
@Component	一般用在身份不明确的组件上
@Service	一般用在service层
@Controller	一般用在控制层
@Repository	一般用在数据库访问层

在applicationContext.xml文件中开启自动扫描

<?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:aop="http://www.springframework.org/schema/aop"
	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-4.3.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd">
			<!--扫描全部 -->
 			<!--  <context:component-scan base-package="com.sxt.*.dao.impl"></context:component-scan>
 		<!--扫描指定文件，一条语句完成 -->
 	<context:component-scan base-package="com.sxt.dao.impl,com.sxt.service.impl,com.sxt.controller"></context:component-scan>-->
    
    <!--扫描指定文件 -->
    <context:component-scan base-package="com.sxt.dao.impl"></context:component-scan>
	<context:component-scan base-package="com.sxt.service.impl"></context:component-scan>
	<context:component-scan base-package="com.sxt.controller"></context:component-scan>
</beans>

在Controller配置

@Controller//该注解作用和在applicationContext.xml中的<bean>的作用是一样的
public class UserController {
	private IUserService service;
	@Resource
	public void setService(IUserService service) {
		this.service = service;
	}
	
	public void say(String msg){
		
	     System.out.println("controller："+service.say(msg));
		
		
	}
}

在dao层的实现类配置

@Repository
public class UserDAOImpl implements IUserDAO {

	@Override
	public String say(String msg) {
		System.out.println("--->"+msg);
		return "hello";
	}


}

在service层实现类配置

@Service
public class UserServiceImpl implements IUserService {
	
	// 调用者与被调用者之间 DI 依赖注入 设值
	   @Resource
		private IUserDAO dao;

		@Override
		public String say(String msg) {
			
			return dao.say(msg);
		}

		
		/**
		 * 设值注入必要提供的setter方法
		 * @param dao
		 */
		public void setDao(IUserDAO dao) {
			this.dao = dao;
		}
}

测试

public class test {
	public static void main(String[] args) {
		ApplicationContext ac=
				new ClassPathXmlApplicationContext("applicationContext.xml");
		UserController controller = ac.getBean(UserController.class);
		   controller.say("aaa");
	}
	
	
	
}

java自动配置

①配置javaConfig

@Configuration
//添加扫描
@ComponentScan("com.sxt.*")
//多个文件扫描
//@ComponentScans(value={@ComponentScan(""),@ComponentScan("")})
/*@ComponentScan(value="com.sxt.*"
				,useDefaultFilters=true
				,excludeFilters={@ComponentScan.Filter(type=FilterType.ANNOTATION,classes=Service.class)})*/
public class javaConfig {

}

②配置dao层实现类

//@Component // 等价于 <bean class="com.sxt.service.impl.UserDaoImpl" name="userDaoImpl"/>
@Repository
public class UserDAOImpl implements IUserDAO {

	@Override
	public String say(String msg) {
		System.out.println("--->"+msg);
		return "hello";
	}
}

③配置service实现类

//@Component // 将当前类交给Spring容器管理
@Service
public class UserServiceImpl implements IUserService {
	
	// 调用者与被调用者之间 DI 依赖注入 设值
	   @Resource
		private IUserDAO dao;

		@Override// 只能根据类型查找
		public String say(String msg) {
			
			return dao.say(msg);
		}

		
		
}

④配置控制层

@Controller
public class UserController {
	
	@Resource
	private IUserService service;
	
	
	public void sleep(){
		System.out.println("休息一会....");
	}
	
	public void say(String msg){
		
	     System.out.println("controller："+service.say(msg));
		
		
	}
}

⑤测试

public class test {
	public static void main(String[] args) {
		ApplicationContext ac=
				new AnnotationConfigApplicationContext(javaConfig.class);
		UserController controller = ac.getBean(UserController.class);
		   controller.say("aaa");
	}