How to check whether code is executed on server or client side in GWT?

Question

I've got one class which is used in both server and client side. How can I do checking in its constructor that it has been called either from client or server class?

I've done it in dirty way - just try if GWT.create() method throws an exception an if it does, run server side code. But how can I avoid this?

    public PrintManager() {
    try {
        factory = GWT.create(MapConfigFactory.class);   //clientsiede factory creation
    } catch (Exception ex) {
        factory = AutoBeanFactorySource.create(MapConfigFactory.class); //serverside factory creator
    }
}

Answer 1

com.google.gwt.core.client.GWT.isScript() returns true when the code is running as JavaScript on the client.

com.google.gwt.core.client.GWT.isClient() returns false when the code is running on the server JVM (shared code).

Answer 2

AutoBeanFactorySource is not shared code, so you cannot use this code on the client. in this case, you need to either:

• use dependency-injection, so that the instance of MapConfigFactory can be provided differently on client-side and server-side
• use super-source to have two files for the same class: one for the client-side, and another one for the server-side. super-source is explained in the Overriding one package implementation with another section of http://code.google.com/webtoolkit/doc/latest/DevGuideOrganizingProjects.html#DevGuideModuleXml, it is used by GWT for the Java runtime emulation and, for instance, for the com.google.gwt.regexp and com.google.gwt.safehtml packages, to provide a unified API that can run in both client and server side.