CODEWITHSUNDEEP
javaapache-camel
andPat
andPat

Reputation: 4513

Switch case in Apache Camel

Is there a construct in Apache Camel (in Java DSL) similar to Java switch-case?

For example:

 from( incomingRoute )
    .choice()
    .when( simple( "${body.getType} == '" + TYPE.A.name() + "'" ) )
                .to( A_Endpoint )
    .when( simple( "${body.getType} == '" + TYPE.B.name() + "'" ) )
                .to( B_Endpoint )
    .when( simple( "${body.getType} == '" + TYPE.C.name() + "'" ) )
                .to( C_Endpoint )
   .otherwise()
                .to( errorEndpoint );

Can be translated into something else more similar to switch? I mean that I do not want to use simple predicates, only value of type of body element. Or is my approach completely wrong? (That could reasonably be)

Upvotes: 4

Views: 4790

Answers (1)

Miloš Milivojević
Miloš Milivojević

Reputation: 5369

I generally prefer using Java 8 lambdas in that particular scenario:

public void configure() throws Exception {
  from( incomingRoute )
     .choice()
     .when( bodyTypeIs( TYPE.A ) )
                 .to( A_Endpoint )
     .when( bodyTypeIs(  TYPE.B ) )
                 .to( B_Endpoint )
     .when( bodyTypeIs(  TYPE.C ) )
                 .to( C_Endpoint )
     .otherwise()
                 .to( errorEndpoint );
}

private Predicate bodyTypeIs(TYPE type) {
  return e -> e.getIn().getBody(BodyType.class).getType() == type;
}

Also, using Camel's Predicates with Java 8 allows for some awesome fluent API building, like adding your own type of functional Predicate:

@FunctionalInterface
public interface ComposablePredicate extends Predicate, java.util.function.Predicate<Exchange> {

  @Override
  default boolean matches(Exchange exchange) {
    return test(exchange);
  }

  @Override
  default ComposablePredicate and(java.util.function.Predicate<? super Exchange> other) {
    Objects.requireNonNull(other);
    return (t) -> test(t) && other.test(t);
  }

  @Override
  default ComposablePredicate negate() {
    return (t) -> !test(t);
  }

  @Override
  default ComposablePredicate or(java.util.function.Predicate<? super Exchange> other) {
    Objects.requireNonNull(other);
    return (t) -> test(t) || other.test(t);
  }
}

Which allows you to write stuff like: 

public void configure() throws Exception {
  from( incomingRoute )
     .choice()
     .when( bodyTypeIs( TYPE.A ) .or ( bodyTypeIs( TYPE.A1 ) ) )
                 .to( A_Endpoint )
     .when( bodyTypeIs(  TYPE.B ).negate() )
                 .to( NOT_B_Endpoint )
     .when( bodyTypeIs(  TYPE.C ) .and ( bodyNameIs( "name" ) ) )
                 .to( C_Endpoint )
     .otherwise()
                 .to( errorEndpoint );
}

private ComposablePredicate bodyTypeIs(TYPE type) {
  return e -> bodyFrom(e).getType() == type;
}

private BodyType bodyFrom(Exchange e) {
  return e.getIn().getBody(BodyType.class);
}

private ComposablePredicate bodyNameIs(String name) {
  return e -> bodyFrom(e).getName().equals(name);
}

Upvotes: 5

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