Most cache APIs are very close to a map in terms of their behavior—you can put some data with put(key, value) and retrieve it back with the same key through a get(key) invocation.
This means that a poor man's cache can be implemented with ConcurrentMap of the JRE:
private final ConcurrentMap<Long, Optional<Quote>> quoteCache = new ConcurrentHashMap<>();@GET@Path("{id}")public JsonQuote findById(@PathParam("id") final long id) { return quoteCache.computeIfAbsent(id, identifier -> quoteService.findById(identifier)) .map(this::convertQuote) .orElseThrow(() -> new WebApplicationException(Response.Status.NO_CONTENT));}
In this implementation, we wrapped the database access in a concurrent map access, which triggers the database ...
