Spring通过ApplicationContext主动获取bean的方法讲解

/** * spring上下文配置 * @author Mingchenchen * */@Componentpublic class SpringContextUtil implements ApplicationContextAware {  private static Logger logger = Logger.getLogger(SpringContextUtil.class);  private static ApplicationContext applicationContext = null;  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException  {    logger.info("------SpringContextUtil setApplicationContext-------");    SpringContextUtil.applicationContext = applicationContext;  }  public static ApplicationContext getApplicationContext() {    return applicationContext;  }  /**   * 注意 bean name默认 = 类名(首字母小写)   * 例如: A8sClusterDao = getBean("k8sClusterDao")   * @param name   * @return   * @throws BeansException   */  public static Object getBean(String name) throws BeansException {    return applicationContext.getBean(name);  }  /**   * 根据类名获取到bean   * @param <T>   * @param clazz   * @return   * @throws BeansException   */  @SuppressWarnings("unchecked")  public static <T> T getBeanByName(Class<T> clazz) throws BeansException {    try {      char[] cs=clazz.getSimpleName().toCharArray();      cs[0] += 32;//首字母大写到小写      return (T) applicationContext.getBean(String.valueOf(cs));    } catch (Exception e) {      e.printStackTrace();      return null;    }   }  public static boolean containsBean(String name) {    return applicationContext.containsBean(name);  }  public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {    return applicationContext.isSingleton(name);  }}

<!-- 初始化Spring容器，让Spring容器随Web应用的启动而自动启动 -->   <listener>     <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>   </listener> 

/** * spring上下文配置 * @author Mingchenchen * */public class SpringContextUtil {  private static Logger logger = Logger.getLogger(SpringContextUtil.class);  //@Autowired 沿用springTest的这种方法 是否会更好？  //ApplicationContext ctx;  private static ApplicationContext applicationContext = null;  public static void setApplicationContext(ApplicationContext applicationContext) throws BeansException {    logger.info("------SpringContextUtil setApplicationContext-------");    SpringContextUtil.applicationContext = applicationContext;  }  //注意此处变成了static  public static ApplicationContext getApplicationContext() {    return applicationContext;  }  /**   * 注意 bean name默认 = 类名(首字母小写)   * 例如: A8sClusterDao = getBean("k8sClusterDao")   * @param name   * @return   * @throws BeansException   */  public static Object getBean(String name) throws BeansException {    return applicationContext.getBean(name);  }  /**   * 根据类名获取到bean   * @param <T>   * @param clazz   * @return   * @throws BeansException   */  @SuppressWarnings("unchecked")  public static <T> T getBeanByName(Class<T> clazz) throws BeansException {    try {      char[] cs=clazz.getSimpleName().toCharArray();      cs[0] += 32;//首字母大写到小写      return (T) applicationContext.getBean(String.valueOf(cs));    } catch (Exception e) {      e.printStackTrace();      return null;    }   }  public static boolean containsBean(String name) {    return applicationContext.containsBean(name);  }  public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {    return applicationContext.isSingleton(name);  }}/** * Descripties: 系统初始化 * @author wangkaiping * 2016年5月23日 上午11:58:09 */@Componentpublic class SystemInit implements InitializingBean,ApplicationContextAware{  private static Logger logger = Logger.getLogger(SystemInit.class);  @Autowired  private ClusterDao clusterDao;  @Override  public void afterPropertiesSet() throws Exception {    logger.info("--------------系统初始化中-------------------");    initClusterCache();//初始化集群数据 必须最开始完成    initRefreshAppStatusTask();    initUpdateAppStatusToDB();    initUpdateSession();    logger.info("--------------系统初始化完成-------------------");  }  /**   * 1.初始化集群数据   */  private void initClusterCache(){    logger.info("1.初始化集群信息到缓存中:ClusterCache开始");    //查询数据库所有的集群数据    List<ClusterEntity> allClusterInfoList = clusterDao.selectAll(ClusterEntity.class, "delete_flag=0");    for (ClusterEntity k8sClusterEntity : allClusterInfoList) {      ClusterCache.put(k8sClusterEntity.getUuid() , k8sClusterEntity);//存入缓存    }    logger.info("1.初始化集群信息到缓存中:ClusterCache完成,总共" + allClusterInfoList.size() + "条数据");  }  /**   * 2.初始化异步任务:刷新所有应用状态   */  private void initRefreshAppStatusTask() {    logger.info("2.初始化任务:RefreshAllAppStatusTask 刷新应用下的k8s的pod状态并存入待更新队列");    RefreshAppStatusExcutor.init();    logger.info("2.初始化任务:RefreshAllAppStatusTask 完成");  }  /**   * 3.初始化异步任务:更新状态到数据库   */  private void initUpdateAppStatusToDB() {    logger.info("3.初始化任务:RefreshToDBTask 从待更新Appinstance队列取出数据并更新数据库");    UpdateAppStatusToDBExcutor.init();    logger.info("3.初始化任务:RefreshToDBTask 完成");  }  /**   * 4. 初始化异步任务： 更新用户的所有session   */  private void initUpdateSession() {    logger.info("4.初始化任务：更新session开始");    UserSessionUpdateExcutor.init();    logger.info("4.初始化任务：更新session结束");  }  ////////////////////////////////////////////////////////////////  //此方法一定不要写成static  @Override  public void setApplicationContext(ApplicationContext applicationContext)                         throws BeansException {    //实际上是把applicationContext传入到了SpringContextUtil里面    SpringContextUtil.setApplicationContext(applicationContext);  }}