How to deploy and read a textfile on glassfish, so that I can use it with jpa and jsf?

Question

I want to use the content of a textfile (it is .xml, but I treat it as a plaintext file) to fill my database via jpa, so I need to place the file somewhere and retrieve it on the (glassfish) server, therefore I use this class:

@Singleton
@Startup
public class Initializer {

    @PostConstruct
    public void populate() {

I found this:

ServletContext context = session.getServletContext();
String realContextPath = context.getRealPath(request.getContextPath());

But I don't know where to get that sessionobject. And I tried this:

ServletContext ctx = (ServletContext) FacesContext.getCurrentInstance().getExternalContext().getContext();
String filename = ctx.getRealPath("/WEB-INF/filename.xml");

This gives me a NullPointerException in the first line.

I've also seen this, but it does not work for me:

ClassLoader classLoader = getClass().getClassLoader();
File file = new File(classLoader.getResource("filename.xml").getFile());

Later I will download the file from another location, but for testing purposes I do not want to download it every time.

Update:

InputStream inputStream;
inputStream = Initializer.class.getResourceAsStream("filename.xml");

This is placed in the same directory as Initializer, but inputStream is null.

And here:

InputStream inputStream;

ServletContext ctx = (ServletContext) FacesContext.getCurrentInstance().getExternalContext().getContext();
inputStream = ctx.getResourceAsStream("/WEB-INF/filename.xml");

The ServletContext is null.

Also null:

InputStream inputStream = getClass().getClassLoader().getResourceAsStream("filename.xml");

And also null (file is in /src/main/java/de/name/):

URL defaultFile = Initializer.class.getResource("/de/name/filename.xml");

Okay, here a different approach - I use the primefaces-extensions showcase in my application and that is able to get file content.

public class ShowcaseUtil {
    public static String getFileContent(final String fullPathToFile) {
        try {
            // Finding in WEB ...
            FacesContext fc = FacesContext.getCurrentInstance();
            InputStream is = fc.getExternalContext().getResourceAsStream(fullPathToFile);
            if (is != null) {
                return FileContentMarkerUtil.readFileContent(fullPathToFile, is);
            }

            // Finding in ClassPath ...
            is = ShowcaseUtil.class.getResourceAsStream(fullPathToFile);
            if (is != null) {
                return FileContentMarkerUtil.readFileContent(fullPathToFile, is);
            }
        } catch (Exception e) {
            throw new IllegalStateException("Internal error: file " + fullPathToFile + " could not be read", e);
        }

        return "";
    }
}

They use it like this:

            <ui:define name="contentTab2">
${showcase:getFileContent('/org/primefaces/extensions/showcase/controller/AjaxErrorHandlerController.java')}
            </ui:define>

So I tried:

String document = ShowcaseUtil.getFileContent("/org/primefaces/extensions/showcase/controller/AjaxErrorHandlerController.java");

But that is not working. So maybe it's because of the Singleton-Environment? I have no clue, so I find it a bit difficult to find a start for looking for answers.