[[fluent-java-routes-api]]
= Fluent Java Routes API

To allow for simple configuration in Java, the `RouteLocatorBuilder` bean includes a fluent API.
The following listing shows how it works:

.GatewaySampleApplication.java
[source,java]
----
// static imports from GatewayFilters and RoutePredicates
@Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder, ThrottleGatewayFilterFactory throttle) {
    return builder.routes()
            .route(r -> r.host("**.abc.org").and().path("/image/png")
                .filters(f ->
                        f.addResponseHeader("X-TestHeader", "foobar"))
                .uri("http://httpbin.org:80")
            )
            .route(r -> r.path("/image/webp")
                .filters(f ->
                        f.addResponseHeader("X-AnotherHeader", "baz"))
                .uri("http://httpbin.org:80")
                .metadata("key", "value")
            )
            .route(r -> r.order(-1)
                .host("**.throttle.org").and().path("/get")
                .filters(f -> f.filter(throttle.apply(1,
                        1,
                        10,
                        TimeUnit.SECONDS)))
                .uri("http://httpbin.org:80")
                .metadata("key", "value")
            )
            .build();
}
----

This style also allows for more custom predicate assertions.
The predicates defined by `RouteDefinitionLocator` beans are combined using logical `and`.
By using the fluent Java API, you can use the `and()`, `or()`, and `negate()` operators on the `Predicate` class.