Hi,
I'm evaluating Flink with the intent to integrate it into a Java project
that uses a lot of dependency injection via Guice. What would be the best
way to work with DI/Guice given that injected fields aren't Serializable?
I looked at this StackOverflow answer so far. To my understanding the
strategy is as follows but I'm not sure about step 3:
1. Use a RichFunction any time injection required.
2. Do not use @Inject, instead mark each injected field as transient.
3. Implement open() / close() and manually assign values to injected
fields using Injector.getInstance(SomeClass.class)? But where do I get the
injector? Create one on the spot each time? Keep one as a static var
somewhere and use everywhere?
Example:
public class MyFilter extends FilterFunction<String> {
private transient DbClient dbClient;
//@Inject DbClient dbClient; //typical Guice field injection
public void open(Configuration parameters) {
// where am I suppose to get the injector?
// keep it as a static variable somewhere and init it in Main?
this.dbClient =
MyInjectorHolder.injector().getInstance(DbClient.class);
}
public boolean filter(String value) {
return this.dbClient.query(value);
}
}
I haven't setup a Flink environment to try the above yet though.
Does anyone know of a less verbose way?
I imagine this could get quite verbose with multiple injected fields.
Thanks,
Xiaochuan Yu
