public static PagingContext getPagingContext(
final ResourceContext context, final PagingContext defaultContext) {
String startString =
ArgumentUtils.argumentAsString(
context.getParameter(RestConstants.START_PARAM), RestConstants.START_PARAM);
String countString =
ArgumentUtils.argumentAsString(
context.getParameter(RestConstants.COUNT_PARAM), RestConstants.COUNT_PARAM);
try {
int defaultStart =
defaultContext == null ? RestConstants.DEFAULT_START : defaultContext.getStart();
int defaultCount =
defaultContext == null ? RestConstants.DEFAULT_COUNT : defaultContext.getCount();
int start =
startString == null || StringUtils.isEmpty(startString.trim())
? defaultStart
: Integer.parseInt(startString);
int count =
countString == null || StringUtils.isEmpty(countString.trim())
? defaultCount
: Integer.parseInt(countString);
if (count < 0 || start < 0) {
throw new RoutingException("start/count parameters must be non-negative", 400);
}
return new PagingContext(start, count, startString != null, countString != null);
} catch (NumberFormatException e) {
throw new RoutingException("Invalid (non-integer) start/count parameters", 400);
}
}
@Finder("searchWithPostFilter")
public CollectionResult<Greeting, Empty> searchWithPostFilter(
@PagingContextParam PagingContext ctx) {
List<Greeting> greetings = new ArrayList<Greeting>();
int idx = 0;
int start = ctx.getStart();
int stop = start + ctx.getCount();
for (Greeting g : _db.values()) {
if (idx++ >= ctx.getStart()) {
greetings.add(g);
if (idx == stop) {
break;
}
}
}
if (greetings.size() > 0)
greetings.remove(0); // for testing, using a post-filter that just removes the first element
int total = _db.values().size();
// but we keep the numElements returned as the full count despite the fact that with the filter
// removed 1
// this is to keep paging consistent even in the presence of a post filter.
return new CollectionResult<Greeting, Empty>(greetings, total, null, PageIncrement.FIXED);
}
private static Integer getNextPageStart(
int elementsOnCurrentPage,
final Integer totalResults,
PagingContext pagingContext,
final PageIncrement pageIncrement) {
if (pageIncrement == PageIncrement.RELATIVE) {
if ((totalResults != null
&& (pagingContext.getStart() + elementsOnCurrentPage < totalResults))
|| (elementsOnCurrentPage == pagingContext.getCount())) {
return pagingContext.getStart() + elementsOnCurrentPage;
} else {
return null; // no next page
}
} else if (pageIncrement == PageIncrement.FIXED) {
if (totalResults == null)
throw new IllegalStateException(
"'total' must be non-null when PageIncrement is FIXED"); // this is also checked by the
// CollectionResult constructor
if (pagingContext.getStart() + pagingContext.getCount() < totalResults) {
return pagingContext.getStart() + pagingContext.getCount();
} else {
return null; // no next page
}
} else {
throw new IllegalStateException("Unrecognized enumeration value: " + pageIncrement);
}
}
@Finder("search")
public List<Greeting> search(
@PagingContextParam PagingContext ctx, @QueryParam("tone") @Optional Tone tone) {
List<Greeting> greetings = new ArrayList<Greeting>();
int idx = 0;
int start = ctx.getStart();
int stop = start + ctx.getCount();
for (Greeting g : _db.values()) {
if (idx++ >= ctx.getStart()) {
if (tone == null || g.getTone().equals(tone)) {
greetings.add(g);
}
if (idx == stop) {
break;
}
}
}
return greetings;
}
@Finder("searchWithTones")
public List<Greeting> searchWithTones(
@PagingContextParam PagingContext ctx, @QueryParam("tones") @Optional Tone[] tones) {
Set<Tone> toneSet = new HashSet<Tone>(Arrays.asList(tones));
List<Greeting> greetings = new ArrayList<Greeting>();
int idx = 0;
int start = ctx.getStart();
int stop = start + ctx.getCount();
for (Greeting g : _db.values()) {
if (idx++ >= ctx.getStart()) {
if (tones == null || toneSet.contains(g.getTone())) {
greetings.add(g);
}
if (idx == stop) {
break;
}
}
}
return greetings;
}
public static CollectionMetadata buildMetadata(
final URI requestUri,
final ResourceContext resourceContext,
final ResourceMethodDescriptor methodDescriptor,
final List<?> resultElements,
final PageIncrement pageIncrement,
final Integer totalResults) {
CollectionMetadata metadata = new CollectionMetadata();
List<Parameter<?>> pagingContextParams =
methodDescriptor.getParametersWithType(Parameter.ParamType.PAGING_CONTEXT_PARAM);
PagingContext defaultPagingContext =
pagingContextParams.isEmpty()
? null
: (PagingContext) pagingContextParams.get(0).getDefaultValue();
PagingContext pagingContext = getPagingContext(resourceContext, defaultPagingContext);
metadata.setCount(pagingContext.getCount());
metadata.setStart(pagingContext.getStart());
if (totalResults != null) {
metadata.setTotal(totalResults);
} else {
metadata.removeTotal();
}
LinkArray links = new LinkArray();
String bestEncoding = RestConstants.HEADER_VALUE_APPLICATION_JSON;
if (resourceContext.getRawRequest() != null) {
bestEncoding =
pickBestEncoding(resourceContext.getRequestHeaders().get(RestConstants.HEADER_ACCEPT));
}
// links use count as the step interval, so links don't make sense with count==0
if (pagingContext.getCount() > 0) {
// prev link
if (pagingContext.getStart() > 0) {
int prevStart = Math.max(0, pagingContext.getStart() - pagingContext.getCount());
String prevUri = buildPaginatedUri(requestUri, prevStart, pagingContext.getCount());
Link prevLink = new Link();
prevLink.setRel("prev");
prevLink.setHref(prevUri);
prevLink.setType(bestEncoding);
links.add(prevLink);
}
// next link if there are more results, or we returned a full page
Integer nextStart =
getNextPageStart(resultElements.size(), totalResults, pagingContext, pageIncrement);
if (nextStart != null) {
// R2 doesn't expose host/port => can't build absolute URI (this is ok, as
// relative URIs internally
String nextUri = buildPaginatedUri(requestUri, nextStart, pagingContext.getCount());
Link nextLink = new Link();
nextLink.setRel("next");
nextLink.setHref(nextUri);
nextLink.setType(bestEncoding);
links.add(nextLink);
}
metadata.setLinks(links);
}
return metadata;
}