osgi - guice - select different providers while running -


i want change provider i'm using @ runtime without having stop jvm. example, isn't i'm trying do, idea same: say, want switch amazon s3 google cloud storage in middle of running application.

is can within guice?

i have have jars available @ runtime , configure modules @ startup. then, later once application started, i'd have use provider can determine instance inject @ startup , later on when changes.

or, better restart application after updating configuration , system proceed configuration , if needs change, application again need restarted.

would osgi here?

you don't need extra: guice can out-of-the-box. but... you'll have use providers instead of direct instance.

in module

bind(cloud.class)   .annotatedwith(names.named("google"))   .to(googlecloud.class); bind(cloud.class)   .annotatedwith(names.named("amazon"))   .to(amazoncloud.class); bind(cloud.class)   .toprovider(switchingcloudprovider.class);

somewhere

class switchingcloudprovider implements provider<cloud> {   @inject @named("google") provider<cloud> googlecloudprovider;   @inject @named("amazon") provider<cloud> amazoncloudprovider;   @inject configuration configuration;        // used switch "commander"   public cloud get() {     switch(configuration.getcloudname()) {       case "google": return googlecloudprovider.get();       case "amazon": return amazoncloudprovider.get();       default:          // whatever want, exception.     }   } }

or in provider method in module

@provides cloud providecloud(     @named("google") provider<cloud> googlecloudprovider,     @named("amazon") provider<cloud> amazoncloudprovider,     configuration configuration) {   switch(configuration.getcloudname()) {     case "google": return googlecloudprovider.get();     case "amazon": return amazoncloudprovider.get();     default:        // whatever want, exception.   } }

usage

class foo {   @inject provider<cloud> cloudprovider; // not inject cloud directly or won't changes come up.   public void bar() {     cloud cloud = cloudprovider.get();     // use cloud   } }

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