项目中的怪问题：常规类居然比Listener先启动

Question

KyllListener.javapublic class KyllListener extends HttpServlet implements ServletContextListener { private static final Log logger = LogFactory.getLog(KyllListener.class);
public void contextInitialized(ServletContextEvent event) {
String rootpath = event.getServletContext().getRealPath("/");
if (rootpath != null) {
rootpath = rootpath.replaceAll("\\\\", "/");
}else {
rootpath = "/";
}
if (!rootpath.endsWith("/")) {
rootpath = rootpath + "/";
}
Global.RGS_HOME = rootpath;
logger.error("根目录是："+Global.RGS_HOME);
}}Global.java
public final class Global{
       //为精简内容，一部分代码已省略
public static String RGS_HOME=null;
}SystemConfigService.java
public class SystemConfigService {
 private static final Log logger = LogFactory.getLog(SystemConfigService.class);
 private static final String SYSTEM_CONFIG_PROPERTIES = "/WEB-INF/config.ini";
 private File configFile = null;  private Properties properties = new Properties();  private static SystemConfigService systemConfigServer = null; 
 
 public static synchronized SystemConfigService getInstance(){
if(systemConfigServer==null){
logger.error("Global.RGS_HOME:"+Global.RGS_HOME);
systemConfigServer = new SystemConfigService(Global.RGS_HOME);
}
return systemConfigServer;
 }
 
 private SystemConfigService(String systemRootPath) {
    try {
     configFile = new File(systemRootPath+SYSTEM_CONFIG_PROPERTIES);
     InputStream configFile = new FileInputStream(this.configFile);
     properties.load(configFile);
     configFile.close();
    }
    catch (Exception e) {
      logger.error(e);
    }
  }
 public Properties getProperties(){
 return this.properties;
 }
}
以上代码大意是TOMCAT启动是利用KyllListener监听到项目的根目录，将其赋值给Global.RGS_HOME，
然后systemConfigServer = new SystemConfigService(Global.RGS_HOME)来初始化systemConfigServer，
这段代码的主要目的是SystemConfigService当中的properties。
现在在启动是显示如下日志：
信息: Starting Servlet Engine: Apache Tomcat/6.0.18
2009-09-09 09:09:41,640 ERROR [com.alt.rgs.SystemConfigService] - Global.RGS_HOME:null
2009-09-09 09:09:41,640 ERROR [com.alt.rgs.SystemConfigService] - java.io.FileNotFoundException: null\WEB-INF\config.ini (系统找不到指定的路径。)
2009-09-09 09:09:41,687 ERROR [com.alt.rgs.system.web.listener.KyllListener] -根目录是：D:/work spaces/rgs/WebRoot/
通过下面这段可以看到在TOMCAT启动时确实取到项目根目录并将其赋值给Global.RGS_HOME了，2009-09-09 09:09:41,687 ERROR [com.alt.rgs.system.web.listener.KyllListener] -根目录是：D:/work spaces/rgs/WebRoot/
但通过启动日志可以看出com.alt.rgs.SystemConfigService初始化在前，com.alt.rgs.system.web.listener.KyllListener初始化在后，在WEB项目中照理应该是Listener类率先初始化的啊，那我这里该如何解释呢。最后，该如何解决我的问题呢？
请各位大侠指教。谢谢各位了。

Answer 1

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" 
xmlns="http://java.sun.com/xml/ns/j2ee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<context-param>
<param-name>webAppRootKey</param-name>
<param-value>rgs.root</param-value>
</context-param>
<context-param>
<param-name>log4jConfigLocation</param-name>
<param-value>/WEB-INF/log4j.properties</param-value>
</context-param> <context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/dataAccessContext-local.xml /WEB-INF/applicationContext.xml</param-value>
</context-param> <listener>
<listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
</listener>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<listener>
<display-name>初始化</display-name>
<listener-class>com.alt.rgs.system.web.listener.KyllListener</listener-class>
</listener>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <jsp-config>
<taglib>
<taglib-uri>/WEB-INF/FCKeditor.tld</taglib-uri>
<taglib-location>/WEB-INF/FCKeditor.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>/WEB-INF/kyll.tld</taglib-uri>
<taglib-location>/WEB-INF/kyll.tld</taglib-location>
</taglib>
</jsp-config>
<servlet>
<description>��装载单位列表（树形单位列表专用）</description>
<servlet-name>LoadUnit4TreeAction</servlet-name>
<servlet-class>com.alt.rgs.system.web.action.LoadUnit4TreeAction</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoadUnit4TreeAction</servlet-name>
<url-pattern>/servlet/LoadUnit4TreeAction.do</url-pattern>
</servlet-mapping>
<servlet>
<description>登录验证</description>
<servlet-name>LoginAction</servlet-name>
<servlet-class>com.alt.rgs.system.action.LoginAction</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginAction</servlet-name>
<url-pattern>/LoginAction.do</url-pattern>
</servlet-mapping>
<servlet>
<description></description>
<servlet-name>searchForKeywordAction</servlet-name>
<servlet-class>com.alt.rgs.search.action.SearchForKeywordAction</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>searchForKeywordAction</servlet-name>
<url-pattern>/servlet/searchForKeywordAction.do</url-pattern>
</servlet-mapping>
<servlet>
<description></description>
<servlet-name>loadRgsTypeAction</servlet-name>
<servlet-class>com.alt.rgs.system.web.action.LoadRgsTypeAction</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>loadRgsTypeAction</servlet-name>
<url-pattern>/servlet/loadRgsTypeAction.do</url-pattern>
</servlet-mapping>
</web-app>这是web.xml的全部内容，因为不大，所以干脆全贴上来了。

Answer 2

问题已经解决，<listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <listener>
        <display-name>初始化</display-name>
        <listener-class>com.alt.rgs.system.web.listener.KyllListener</listener-class>
    </listener>把这2个Listener的顺序调换一下就OK了，
各位应该知道why吧？
我就不细说了

Answer 3

 if (listener != NULL) void Camera::dataCallbackTimestamp(nsecs_t timestamp, int32_t msgType, const sp<IMemory>& dataPtr)sp<CameraListener> listener;
    {
        Mutex::Autolock _l(mLock);
        listener = mListener;
            }
    if (listener != NULL) {
 
        listener->postDataTimestamp(timestamp, msgType, dataPtr);
    } else {
        LOGW("No listener was set. Drop a recording frame.");
        releaseRecordingFrame(dataPtr);
    }