一個(gè)applicationContext加載錯(cuò)誤導(dǎo)致的阻塞問題及解決方法

<?xml version="1.0" encoding="UTF-8" ?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
     version="3.0">
 <display-name>xx-test</display-name>
 <filter>
  <filter-name>encodingFilter</filter-name>
  <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  <init-param>
   <param-name>encoding</param-name>
   <param-value>UTF-8</param-value>
  </init-param>
  <init-param>
   <param-name>forceEncoding</param-name>
   <param-value>true</param-value>
  </init-param>
 </filter>
 <filter-mapping>
  <filter-name>encodingFilter</filter-name>
  <url-pattern>/*</url-pattern>
 </filter-mapping>
 <servlet>
  <servlet-name>spring</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <init-param>
   <param-name>contextConfigLocation</param-name>
   <param-value>classpath:spring/spring-servlet.xml</param-value>
  </init-param>
  <load-on-startup>1</load-on-startup>
 </servlet>
 <servlet-mapping>
  <servlet-name>spring</servlet-name>
  <url-pattern>/</url-pattern>
 </servlet-mapping>
</web-app>

 <filter>
  <filter-name>SessionFilter</filter-name>
  <filter-class>com.xxx.session.redisSessionFilter</filter-class>
 </filter>
 <filter-mapping>
  <filter-name>SessionFilter</filter-name>
  <url-pattern>/*</url-pattern>
 </filter-mapping>
 <listener>
  <listener-class>com.xx.session.SSOHttpSessionListener</listener-class>
 </listener>
 <filter>
  <filter-name>SSOFilter</filter-name>
  <filter-class>com.xxx.auth.SSOFilter</filter-class>
 </filter>
 <filter-mapping>
  <filter-name>SSOFilter</filter-name>
  <url-pattern>/*</url-pattern>
 </filter-mapping>
 <context-param>
  <param-name>configFileLocation</param-name>
  <param-value>abc</param-value>
 </context-param>

 // 如: java.net.URLClassLoader.findClass() 拋出的異常
  protected Class<?> findClass(final String name)
    throws ClassNotFoundException
  {
    final Class<?> result;
    try {
      result = AccessController.doPrivileged(
        new PrivilegedExceptionAction<Class<?>>() {
          public Class<?> run() throws ClassNotFoundException {
            String path = name.replace('.', '/').concat(".class");
            Resource res = ucp.getResource(path, false);
            if (res != null) {
              try {
                return defineClass(name, res);
              } catch (IOException e) {
                throw new ClassNotFoundException(name, e);
              }
            } else {
              return null;
            }
          }
        }, acc);
    } catch (java.security.PrivilegedActionException pae) {
      throw (ClassNotFoundException) pae.getException();
    }
    if (result == null) {
      // 此處拋出的異常可以被 idea 捕獲
      throw new ClassNotFoundException(name);
    }
    return result;
  }

  static {
    // 原罪在這里
    CAS_EDIS_CLIENT_TEMPLATE = CasSpringContextUtils.getBean("casRedisClientTemplate", CasRedisClientTemplate.class);
  }

  public static <T> T getBean(String name, Class<T> beanType) {
    return getApplicationContext().getBean(name, beanType);
  }

  public static ApplicationContext getApplicationContext() {
    synchronized (CasSpringContextUtils.class) {
      while (applicationContext == null) {
        try {
          // 沒錯(cuò),就是這里了, 這里設(shè)置了死鎖，線程交出，等待1分鐘超時(shí)，繼續(xù)循環(huán)
          CasSpringContextUtils.class.wait(60000);
        } catch (InterruptedException ex) {
        }
      }
      return applicationContext;
    }
  }

  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    synchronized (CasSpringContextUtils.class) {
      CasSpringContextUtils.applicationContext = applicationContext;
      // 夢(mèng)想總是很美好，當(dāng)加載完成后，通知 wait()
      CasSpringContextUtils.class.notifyAll();
    }
  }

 <!-- 提前加載spring -->
 <context-param>
  <param-name>contextConfigLocation</param-name>
  <param-value>classpath:spring/applicationContext.xml</param-value>
 </context-param>
 <listener>
  <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
 </listener>

  /**
   * Initialize the root web application context.
   */
  @Override
  public void contextInitialized(ServletContextEvent event) {
    initWebApplicationContext(event.getServletContext());
  }

/**
   * Configure the set of instantiated application event listeners
   * for this Context.
   * @return <code>true</code> if all listeners wre
   * initialized successfully, or <code>false</code> otherwise.
   */
  public boolean listenerStart() {
    if (log.isDebugEnabled())
      log.debug("Configuring application event listeners");
    // Instantiate the required listeners
    String listeners[] = findApplicationListeners();
    Object results[] = new Object[listeners.length];
    boolean ok = true;
    for (int i = 0; i < results.length; i++) {
      if (getLogger().isDebugEnabled())
        getLogger().debug(" Configuring event listener class '" +
          listeners[i] + "'");
      try {
        String listener = listeners[i];
        results[i] = getInstanceManager().newInstance(listener);
      } catch (Throwable t) {
        t = ExceptionUtils.unwrapInvocationTargetException(t);
        ExceptionUtils.handleThrowable(t);
        getLogger().error(sm.getString(
            "standardContext.applicationListener", listeners[i]), t);
        ok = false;
      }
    }
    if (!ok) {
      getLogger().error(sm.getString("standardContext.applicationSkipped"));
      return false;
    }
    // Sort listeners in two arrays
    ArrayList<Object> eventListeners = new ArrayList<>();
    ArrayList<Object> lifecycleListeners = new ArrayList<>();
    for (int i = 0; i < results.length; i++) {
      if ((results[i] instanceof ServletContextAttributeListener)
        || (results[i] instanceof ServletRequestAttributeListener)
        || (results[i] instanceof ServletRequestListener)
        || (results[i] instanceof HttpSessionIdListener)
        || (results[i] instanceof HttpSessionAttributeListener)) {
        eventListeners.add(results[i]);
      }
      if ((results[i] instanceof ServletContextListener)
        || (results[i] instanceof HttpSessionListener)) {
        lifecycleListeners.add(results[i]);
      }
    }
    // Listener instances may have been added directly to this Context by
    // ServletContextInitializers and other code via the pluggability APIs.
    // Put them these listeners after the ones defined in web.xml and/or
    // annotations then overwrite the list of instances with the new, full
    // list.
    for (Object eventListener: getApplicationEventListeners()) {
      eventListeners.add(eventListener);
    }
    setApplicationEventListeners(eventListeners.toArray());
    for (Object lifecycleListener: getApplicationLifecycleListeners()) {
      lifecycleListeners.add(lifecycleListener);
      if (lifecycleListener instanceof ServletContextListener) {
        noPluggabilityListeners.add(lifecycleListener);
      }
    }
    setApplicationLifecycleListeners(lifecycleListeners.toArray());
    // Send application start events
    if (getLogger().isDebugEnabled())
      getLogger().debug("Sending application start events");
    // Ensure context is not null
    getServletContext();
    context.setNewServletContextListenerAllowed(false);
    Object instances[] = getApplicationLifecycleListeners();
    if (instances == null || instances.length == 0) {
      return ok;
    }
    ServletContextEvent event = new ServletContextEvent(getServletContext());
    ServletContextEvent tldEvent = null;
    if (noPluggabilityListeners.size() > 0) {
      noPluggabilityServletContext = new NoPluggabilityServletContext(getServletContext());
      tldEvent = new ServletContextEvent(noPluggabilityServletContext);
    }
    for (int i = 0; i < instances.length; i++) {
      if (!(instances[i] instanceof ServletContextListener))
        continue;
      ServletContextListener listener =
        (ServletContextListener) instances[i];
      try {
        fireContainerEvent("beforeContextInitialized", listener);
        // 調(diào)用 listener.contextInitialized() 觸發(fā) listener
        if (noPluggabilityListeners.contains(listener)) {
          listener.contextInitialized(tldEvent);
        } else {
          listener.contextInitialized(event);
        }
        fireContainerEvent("afterContextInitialized", listener);
      } catch (Throwable t) {
        ExceptionUtils.handleThrowable(t);
        fireContainerEvent("afterContextInitialized", listener);
        getLogger().error
          (sm.getString("standardContext.listenerStart",
                 instances[i].getClass().getName()), t);
        ok = false;
      }
    }
    return (ok);
  }