Appengine with Google Cloud Endpoints and Guice - google-app-engine

Question

So i want to use Guice in Appengine with Cloud Endpoints to inject my services, or daos - pretty common I guess, but I found no tutorial for this.
Official Guice for Appengine documentation seems to be here: https://github.com/google/guice/wiki/GoogleAppEngine
When configuring Guice you set up the com.google.inject.servlet.GuiceFilter to intercept every request "/*". And at some point you must initialize the modules. Like the documentation says a good place to do that is a ServletContextListener.
One special kind of Module are ServletModules, that map request-Paths to Servlet-Classes, instead of doing this in the web.xml you can now do this programmatically.
Pretty straight forward up until here. But how do I configure Guice to also include the Endpoint-Classes?

Answer 1

Turns out there is a GuiceSystemServiceServletModule that handles exactly this.
public class GuiceSSSModule extends GuiceSystemServiceServletModule {
#Override
protected void configureServlets() {
super.configureServlets();
Set<Class<?>> serviceClasses = new HashSet<Class<?>>();
serviceClasses.add(MyEndpoint.class);
serviceClasses.add(AnotherAndpoint.class);
this.serveGuiceSystemServiceServlet("/_ah/spi/*", serviceClasses);
}
}
Include this module in the Injector construction in your ServletContextListener:
public class MyGSCL extends GuiceServletContextListener {
#Override
protected Injector getInjector() {
return Guice.createInjector(new GuiceSSSModule(), new BaseModule());
}
}
and use this listener in your web.xml:
<listener>
<listener-class>de.mypkg.MyGSCL</listener-class>
</listener>
Also make sure to include the Guice filter in your web.xml:
<!-- GUICE -->
<filter>
<filter-name>guiceFilter</filter-name>
<filter-class>com.google.inject.servlet.GuiceFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>guiceFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
Your endpoints will be available under /_ah/api/... again and you can use #Inject in your endpoint classes.