I tried the modification you suggested (with the correct method name on the
end) but still with the same results. I also printed out a debug message just
to see what class loader was being used (not that I know what to do with it :-P
)
log.debug("this class loader: " +
this.getClass().getClassLoader().getClass().getName());
Class singletongClassObj =
this.getClass().getClassLoader().loadClass(singletonClassName);
The class loader for the SingletonLoader is:
org.apache.catalina.loader.StandardClassLoader.
The classes that it is looking for are located in the
/apache-tomcat-5.5.23/webapps/myExternalApp/WEB-INF/classes directory.
Filip Hanik - Dev Lists <[EMAIL PROTECTED]> wrote:
did you try
Class singletongClassObj =
this.getClass().getClassLoader().loadName(singletonClassName);
Filip
Mike Peremsky wrote:
> I think this may be a class loader issue, but am not sure as I have never
> really worked with them before. I am putting together a JAR file that
> contains a set of classes to be used throughout a suite of applications. I
> have a class called SingletonLoader that was working when it was within the
> main application, but when I broke out the reusable classes into a separate
> jar file and modified the contextInitialized() method to dynamically load the
> classes it is failing to fid the classes. The contextInitialized() method is
> properly reading the class names from the property file (e.g.
> SINGLETON_LOADER_CLASSES=com.externalApp.singleton.Countries,com.externalApp.singleton.SecurityQuestions)
> and looping through them, but I always get the following error message when
> the line
>
> Class singletongClassObj = Class.forName(singletonClassName);
>
> is executed:
>
> Unable to load singleton: com.externalApp.singleton.Countries
> java.lang.ClassNotFoundException: com.externalApp.singleton.Countries
>
> ALL of the singleton classes to be loaded implement the Singleton interface
> (which has nothing in it, it is just used to denote a class that MUST specify
> a "public static anyReturnVal getInstance()" method.
>
> public class SingletonLoader implements ServletContextListener, SystemConsts {
> /**
> * Logger for this class
> */
> private static final Logger log = Logger.getLogger(SingletonLoader.class);
> private static final String SINGLETON_LOADER_CLASSES
> = "SINGLETON_LOADER_CLASSES";
> private static final String DELIMITER = ",";
> // This is the method defined
> private static final String GET_INSTANCE_METHOD = "getInstance";
> private static final Object ARG_LIST[] = new Object[0];
>
> /**
> * Constructs a new SingletonLoader object.
> */
> public SingletonLoader() {
> }
>
> /**
> * Notification that the web application is ready to process requests.
> *
> * Initializes all of the singletons so they are ready for immediate use
> * after the containet server starts.
> *
> * @param sce This is the event object for notifications about changes to the
> * servlet context of a web application.
> *
> */
> public void contextInitialized(ServletContextEvent sce) {
>
> log.debug("contextInitialized: BEGIN");
> String singletons = ExtProperties.getProperty(SYS_PROPS,
> SINGLETON_LOADER_CLASSES);
>
> if (!StringUtils.isNullOrZeroLen(singletons)) {
> DelimitedString ds = new DelimitedString(singletons, DELIMITER);
> int max = ds.size();
> String singletonClassName = null;
>
> for (int ndx=0; ndx < max; ndx++) {
> try {
> singletonClassName = ds.getEntry(ndx);
> log.debug("Get singletonClassName: " + singletonClassName);
> // Get the singleton class to load
> Class singletongClassObj = Class.forName(singletonClassName);
> log.debug("singletongClassObj: " + singletongClassObj);
> Method method = singletongClassObj.getMethod(GET_INSTANCE_METHOD,
> singletongClassObj);
> method.invoke(null, ARG_LIST);
>
> } catch (Exception e) {
> log.error("Unable to load singleton: " + singletonClassName, e);
> }
> }
> }
> log.debug("contextInitialized: END");
> }
>
> /**
> * Notification that the servlet context is about to be shut down.
> *
> * @param sce the ServletContextEvent
> */
> public void contextDestroyed(ServletContextEvent sce) {
> }
> }
>
> Example of the Countries singleton
>
>
> public class Countries implements DbConsts, Singleton {
> private static Logger log = Logger.getLogger(Countries.class);
>
>
>
> /** Creates a new instance of Countries */
> private Countries() {
> refreshData();
> }
>
> /**
> * Returns the single instance of this class.
> *
> * @return the instance of this class.
> */
> public static Countries getInstance() {
> if (instance == null) {
> synchronized (Countries.class) {
> if (instance == null) {
> instance = new Countries();
> }
> }
> }
> return instance;
> }
>
>
> }
>
>
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