Java 如何从spring容器中获取注入的bean对象

 import org.apache.struts2.ServletActionContext; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.web.context.WebApplicationContext; import org.springframework.web.context.support.WebApplicationContextUtils;

 /** * 从spring容器中获取注入的bean对象 * @explain 必须获取到ServletContext对象，Controller层以struts2为例 * @author Marydon * @creationTime 2018年6月1日上午10:06:49 * @version 1.0 * @since * @email marydon20170307@163.com */ public final class BeansUtils { private static final Logger logger = LoggerFactory.getLogger(BeansUtils.class); private static ApplicationContext ctx; private static WebApplicationContext webCtx; // 静态代码块：加载该类时会被运行的代码 static { if (ctx == null) { try { // 入参需要拿到ServletContext对象 webCtx = WebApplicationContextUtils .getRequiredWebApplicationContext(ServletActionContext.getServletContext()); logger.info("从web.xml容器中加载spring-config.xml"); } catch (Exception e) { logger.info("直接加载spring-config.xml"); } if (webCtx == null) // 你可以自定义spring配置文件的文件名 ctx = new ClassPathXmlApplicationContext("spring-config.xml"); } } /** * 通过beanID获取bean实例 * * @param beanID *      bean的代码 * @return 返回对应的实例 * @throws RuntimeException *       bean没有定义 */ public static Object getBeanInstance(String beanID) throws RuntimeException { logger.info("在spring容器中获取Bean对象 ID=" + beanID); Object obj; if (BeansUtils.ctx == null) { if (BeansUtils.webCtx.containsBeanDefinition(beanID)) { obj = BeansUtils.webCtx.getBean(beanID); } else { logger.info("beanID=" + beanID + "没有定义"); throw new RuntimeException(beanID + "没有定义!"); } } else { if (BeansUtils.ctx.containsBeanDefinition(beanID)) { obj = BeansUtils.ctx.getBean(beanID); } else { logger.info("beanID=" + beanID + "没有定义"); throw new RuntimeException(beanID + "没有定义!"); } } return obj; } }