获取spring bean的几种方法

方法一：在初始化时保存ApplicationContext对象

1. ApplicationContext ac = new FileSystemXmlApplicationContext("applicationContext.xml");
2. ac.getBean("userService");//比如：<bean id="userService" class="com.cloud.service.impl.UserServiceImpl"></bean>

方法二：通过Spring提供的工具类获取ApplicationContext对象

1. ApplicationContext ac1 = WebApplicationContextUtils.getRequiredWebApplicationContext(ServletContext sc);
2. ApplicationContext ac2 = WebApplicationContextUtils.getWebApplicationContext(ServletContext sc);
3. ac1.getBean("beanId");
4. ac2.getBean("beanId");

方法三：通过Spring提供的ContextLoader

1. WebApplicationContext wac = ContextLoader.getCurrentWebApplicationContext();
2. wac.getBean(beanID);
3. 例子：BookDao bookDao = (BookDao) ContextLoader.getCurrentWebApplicationContext().getBean("bookDao");
              Bok bok = bookDao.getBok(1);