Why jre makes unnecessary trips to server for getting properties file

Question

Hi,
I'm using ResourceBundle.getBundle("myresource") method for loading the resourcebundle. I have placed my myresource.properties file in the jar which loaded, when UI getting loaded. But I could see from the java console(by entering 5), that java-plugin makes several trips to server, though I have the file in the client loaded jar file. How can I avoid it. Thanks for any help.
The search goes as follows:
Opening http://<servername>:7001/myresource.class
Connecting http://<servername>:7001/myresource.class with no proxy
Connecting http://<servername>:7001/myresource.class with cookie "JSESSIONID=APBnBCd2y8mJRQgGM9GqzXAT197iMQv7SaM9QORKg5mxvyp1PRKh!-1116598258"
Opening http://<servername>:7001/myresource_en.class
Connecting http://<servername>:7001/myresource_en.class with no proxy
Connecting http://<servername>:7001/myresource_en.class with cookie "JSESSIONID=APBnBCd2y8mJRQgGM9GqzXAT197iMQv7SaM9QORKg5mxvyp1PRKh!-1116598258"
Opening http://<servername>:7001/myresource_en.properties
Connecting http://<servername>:7001/myresource_en.properties with no proxy
Connecting http://<servername>:7001/myresource_en.properties with cookie "JSESSIONID=APBnBCd2y8mJRQgGM9GqzXAT197iMQv7SaM9QORKg5mxvyp1PRKh!-1116598258"
Opening http://<servername>:7001/myresource_en_US.class
Connecting http://<servername>:7001/myresource_en_US.class with no proxy
Connecting http://<servername>:7001/myresource_en_US.class with cookie "JSESSIONID=APBnBCd2y8mJRQgGM9GqzXAT197iMQv7SaM9QORKg5mxvyp1PRKh!-1116598258"
Thanks

Answer 1

The reason the unnecessary trips are being made is that the ResourceBundle is using the default class loader to find the resource files. When a resource can't be found in the jar file, it will send a request to the server to see if it exists there. For the locale "en_US" and the bundle name "myresource", the ResourceBundle will attempt to load all of the following resources:
   myresource.class
   myresource.properties
   myresource_en.class
   myresource_en.properties
   myresource_en_US.class
   myresource_en_US.propertiesSince, you only had "myresource.properties" in your jar file, the ClassLoader attempted to find the other resources on the server.
The following code can be used to create a resource bundle that uses a special classloader that only searches the included jar or zip files. This only works on 1.2 or greater JVMs.
   public ResourceBundle getResourceBundle(String bundleName) {
      ClassLoader rcl = null;
      Locale l = Locale.getDefault();
      ClassLoader cl = this.getClass().getClassLoader();
      if (cl instanceof java.net.URLClassLoader) {
         java.net.URLClassLoader ucl = (java.net.URLClassLoader)cl;
         URL[] urls = ucl.getURLs();
         ArrayList jarUrls = new ArrayList();
         for (int i=0; i<urls.length; i++) {
            String path = urls.getPath();
if ((path.endsWith(".jar")) || (path.endsWith(".JAR")) ||
(path.endsWith(".zip")) || (path.endsWith(".ZIP")))
jarUrls.add(urls[i]);
URL[] newUrls = new URL[jarUrls.size()];
jarUrls.toArray(newUrls);
rcl = java.net.URLClassLoader.newInstance(newUrls, null);
} else {
rcl = cl;
DiagUtils.log("Resource bundle: " + bundleName + " initializing...");
ResourceBundle rb = ResourceBundle.getBundle(bundleName, l, rcl);
DiagUtils.log("Resource bundle: " + bundleName + " initialized.");
return rb;
The basic idea behind this code is to create a new URLClassLoader which only contains URLs that end with ".jar" or ".zip". The parent classloader must be set to null in the newInstance method.
This will not work on the MSJVM because URLClassLoader was introduced with JDK 1.2.
I hope this helps.
-jonp