Accessing resources in a WAR file

you can easily read the content of a directory in Java, even if this directory is in the classpath:

Here is a useful method to load only the resources:

public static List getDirContent(String dir, boolean throwExceptionIfNotFound) throws IOException {

ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();

URL configDir = contextClassLoader.getResource(dir);

if (configDir == null && throwExceptionIfNotFound) throw new IllegalArgumentException("Unable to locate directory " + dir);

List result = new ArrayList();

if (configDir != null) {

URLConnection openConnection = configDir.openConnection();

openConnection.connect();

InputStream is = openConnection.getInputStream();

String content = NuonFileUtils.convertStreamToString(is);

String[] resources = content.split("\n");

for (String resource : resources) {

URL resurl = Thread.currentThread().getContextClassLoader().getResource(resource);

result.add(resurl);

}

}

return result;

}

the content of the resource can be read with a URL using its InputStream.

This method doesn't work in a WAR file, since the classloader's resource locator can't introspect the WAR file. The solution is to use the ServletContext and ServletConfig pattern:

in a JSP, you can do:

String path = ""/WEB-INF/config";

java.net.URL url = config.getServletContext().getResource(path);

and it works beautyfully!

The more elegant way is to have a ServletContextListener intercepting your servlet's initialization, and loading the resources:

public void contextInitialized(ServletContextEvent sce) {

String path = "/WEB-INF/classes";

try {

sce.getServletContext().getResource(path);

} catch (MalformedURLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}