一、ApplicationContextAware 用处
Spring 提供了ApplicationContextAware类,通过它可以获取所有bean上下文。
二、怎么用?
①、定义一个工具类,去实现 ApplicationContextAware,实现 setApplicationContext方法即可
public class SpringContextUtil implements ApplicationContextAware { private static ApplicationContext applicationContext; // Spring应用上下文环境 @Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
SpringContextUtil.applicationContext = applicationContext;
} /**
* 获取对象
*
* @param name
* @return Object 一个以所给名字注册的bean的实例
* @throws BeansException
*/
public static Object getBean(String name) throws BeansException {
return applicationContext.getBean(name);
} }
②、业务代码
public interface UserReadService { public UserInfo getUserInfoById(Long id);
} @Component("userReadService")
public class UserReadServiceImpl implements UserReadService { @Override
public UserInfo getUserInfoById(Long id) {
System.out.println("获取用户信息");
return null;
} }
③、xml 配置
<?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-4.1.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.1.xsd"> <context:annotation-config />
<!--自动扫描含有@Service将其注入为bean -->
<context:component-scan base-package="com.mycompany.yuanmeng.springdemo.aop" /> <bean id="springContextUtil" class="com.mycompany.yuanmeng.springdemo.aop.SpringContextUtil" /> </beans>
④、test
public static void test() { new ClassPathXmlApplicationContext("spring.xml"); // 加载ApplicationContext(模拟启动web服务), 当然如果是用web工程的话,可以直接在web.xml配置,容器会去加载此文件。 UserReadService userReadService = (UserReadService) SpringContextUtil.getBean("userReadService"); userReadService.getUserInfoById(null);
}