The strategy design pattern dynamically chooses an implementation algorithm, a strategy, at runtime. The pattern can be used to select different business algorithms depending on the circumstances.
We could define different algorithm implementations as separate classes. Or we make use of Java SE 8 lambdas and functions, that serve as lightweight strategy implementation here.
CDI is capable of injecting parameterized types:
public class Greeter {
@Inject
Function<String, String> greetingStrategy;
public String greet(String name) {
return greetingStrategy.apply(name);
}
}A CDI producer creates and exposes the greeting depending on the dynamic logic. The actual strategy is represented by the Function type and being selected dynamically:
public class GreetingStrategyExposer {
private final Function<String, String> formalGreeting = name -> "Dear " + name;
private final Function<String, String> informalGreeting = name -> "Hey " + name;
@Produces
public Function<String, String> exposeStrategy() {
// select a strategy
...
return strategy;
}
}| Published on Java Code Geeks with permission by Sebastian Daschner, partner at our JCG program. See the original article here: Strategy Pattern with CDI and lambdas Opinions expressed by Java Code Geeks contributors are their own. |
