Bind different maps using guice

Question

I have a map in my file like:

workflowProperties1 = { "key1" : "value1"; "key2": "value2"; };

workflowProperties2 = { "key1" : "value1"; "key2": "value2"; };

I want to inject this map in a constructor of a class using guice. I am doing something like:

@Inject public myClass(@Named("workflowProperties1") Map<String,String> someMap) { }

Can some one suggest how I inject one of the two maps (workflowProperties1 or workflowProperties2) in myClass above based on a static parameter value?

Answer 1

A solution might be to use Guice Multibindings. Please note that the multibinders are not included in the core Guice so you will need an extra dependency to com.google.inject.extensions:guice-multibindings.

Then you may define your binding module, something like this (in reality you will extract the key/value-s from your file):

@Override
protected void configure()
{
    MapBinder<String, String> wf1Binder = MapBinder.newMapBinder(
                    binder(), 
                    String.class, 
                    String.class, Names.named("workflowProperties1"));

    wf1Binder.addBinding("WF1Key").toInstance("WF1Value");

    MapBinder<String, String> wf2Binder = MapBinder.newMapBinder(
                    binder(), 
                    String.class, 
                    String.class, Names.named("workflowProperties2"));

    wf2Binder.addBinding("WF2Key").toInstance("WF2Value");
}

Then you can easily inject the right map "based on a static parameter value" as you asked e.g:

private static final String STATIC_PARAMETER_VALUE = "workflowProperties1";

@Inject
@Named(STATIC_PARAMETER_VALUE) 
Map<String,String> someMap;