package org.jboss.resteasy.core.request;

import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Variant;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Map.Entry;


Variant selection.
Author:Pascal S. de Kloe
See Also:
  • RFC 2296
/** * {@link Variant} selection. * * @author Pascal S. de Kloe * @see "RFC 2296" */
public class ServerDrivenNegotiation { private Map<MediaType, QualityValue> requestedMediaTypes = null; private Map<String, QualityValue> requestedCharacterSets = null; private Map<String, QualityValue> requestedEncodings = null; private Map<Locale, QualityValue> requestedLanguages = null; private int mediaRadix = 1; public ServerDrivenNegotiation() { } public void setAcceptHeaders(List<String> headerValues) { requestedMediaTypes = null; if (headerValues == null) return; Map<MediaType, QualityValue> requested = null; for (String headerValue : headerValues) { Map<MediaType, QualityValue> mapping = AcceptHeaders.getMediaTypeQualityValues(headerValue); if (mapping == null) return; if (requested == null) requested = mapping; else requested.putAll(mapping); } requestedMediaTypes = requested; for (Iterator<MediaType> it = requested.keySet().iterator(); it.hasNext(); ) { mediaRadix = Math.max(mediaRadix, it.next().getParameters().size()); } } public void setAcceptCharsetHeaders(List<String> headerValues) { requestedCharacterSets = null; if (headerValues == null) return; Map<String, QualityValue> requested = null; for (String headerValue : headerValues) { Map<String, QualityValue> mapping = AcceptHeaders.getStringQualityValues(headerValue); if (mapping == null) return; if (requested == null) requested = mapping; else requested.putAll(mapping); } requestedCharacterSets = requested; } public void setAcceptEncodingHeaders(List<String> headerValues) { requestedEncodings = null; if (headerValues == null) return; Map<String, QualityValue> requested = null; for (String headerValue : headerValues) { Map<String, QualityValue> mapping = AcceptHeaders.getStringQualityValues(headerValue); if (mapping == null) return; if (requested == null) requested = mapping; else requested.putAll(mapping); } requestedEncodings = requested; } public void setAcceptLanguageHeaders(List<String> headerValues) { requestedLanguages = null; if (headerValues == null) return; Map<Locale, QualityValue> requested = null; for (String headerValue : headerValues) { Map<Locale, QualityValue> mapping = AcceptHeaders.getLocaleQualityValues(headerValue); if (mapping == null) return; if (requested == null) requested = mapping; else requested.putAll(mapping); } requestedLanguages = requested; } public Variant getBestMatch(List<Variant> available) { // BigDecimal bestQuality = BigDecimal.ZERO; VariantQuality bestQuality = null; Variant bestOption = null; for (Variant option : available) { VariantQuality quality = new VariantQuality(); if (!applyMediaType(option, quality)) continue; if (!applyCharacterSet(option, quality)) continue; if (!applyEncoding(option, quality)) continue; if (!applyLanguage(option, quality)) continue; // BigDecimal optionQuality = quality.getOverallQuality(); // if (isBetterOption(bestQuality, bestOption, optionQuality, option)) if (isBetterOption(bestQuality, bestOption, quality, option)) { // bestQuality = optionQuality; bestQuality = quality; bestOption = option; } } return bestOption; }
Tests whether option is preferable over the current bestOption.
/** * Tests whether {@code option} is preferable over the current {@code bestOption}. */
// private static boolean isBetterOption(BigDecimal bestQuality, Variant best, // BigDecimal optionQuality, Variant option) private static boolean isBetterOption(VariantQuality bestQuality, Variant best, VariantQuality optionQuality, Variant option) { if (best == null) return true; // Compare overall quality. int signum = bestQuality.getOverallQuality().compareTo(optionQuality.getOverallQuality()); if (signum != 0) return signum < 0; // Overall quality is the same. // Assuming the request has an Accept header, a VariantQuality has a non-null // requestMediaType if and only if it the corresponding Variant has a non-null mediaType. // If bestQuality and optionQuality both have a non-null requestMediaType, we compare them // for specificity. MediaType bestRequestMediaType = bestQuality.getRequestMediaType(); MediaType optionRequestMediaType = optionQuality.getRequestMediaType(); if (bestRequestMediaType != null && optionRequestMediaType != null) { if (bestRequestMediaType.getType().equals(optionRequestMediaType.getType())) { if (bestRequestMediaType.getSubtype().equals(optionRequestMediaType.getSubtype())) { int bestCount = bestRequestMediaType.getParameters().size(); int optionCount = optionRequestMediaType.getParameters().size(); if (optionCount > bestCount) { return true; // more matching parameters } else if (optionCount < bestCount) { return false; // less matching parameters } } else if (bestRequestMediaType.getSubtype().equals("*")) { return true; } else if (optionRequestMediaType.getSubtype().equals("*")) { return false; } } else if (bestRequestMediaType.getType().equals("*")) { return true; } else if (optionRequestMediaType.getType().equals("*")) { return false; } } // Compare variant media types for specificity. MediaType bestType = best.getMediaType(); MediaType optionType = option.getMediaType(); if (bestType != null && optionType != null) { if (bestType.getType().equals(optionType.getType())) { // Same type if (bestType.getSubtype().equals(optionType.getSubtype())) { // Same subtype int bestCount = bestType.getParameters().size(); int optionCount = optionType.getParameters().size(); if (optionCount > bestCount) return true; // more matching parameters else if (optionCount < bestCount) return false; // less matching parameters } else if ("*".equals(bestType.getSubtype())) { return true; // more specific subtype } else if ("*".equals(optionType.getSubtype())) { return false; // less specific subtype } } else if ("*".equals(bestType.getType())) { return true; // more specific type } else if ("*".equals(optionType.getType())) { return false; // less specific type; } } // Finally, compare specificity of the variants. return getExplicitness(best) < getExplicitness(option); } private static int getExplicitness(Variant variant) { int explicitness = 0; if (variant.getMediaType() != null) ++explicitness; if (variant.getEncoding() != null) ++explicitness; if (variant.getLanguage() != null) ++explicitness; return explicitness; } private boolean applyMediaType(Variant option, VariantQuality quality) { if (requestedMediaTypes == null) return true; MediaType mediaType = option.getMediaType(); if (mediaType == null) return true; String type = mediaType.getType(); if ("*".equals(type)) type = null; String subtype = mediaType.getSubtype(); if ("*".equals(subtype)) subtype = null; Map<String, String> parameters = mediaType.getParameters(); if (parameters.isEmpty()) parameters = null; QualityValue bestQuality = QualityValue.NOT_ACCEPTABLE; int bestMatchCount = -1; MediaType bestRequestMediaType = null; for (MediaType requested : requestedMediaTypes.keySet()) { int matchCount = 0; if (type != null) { String requestedType = requested.getType(); if (requestedType.equals(type)) matchCount += mediaRadix * 100; else if (!"*".equals(requestedType)) continue; } if (subtype != null) { String requestedSubtype = requested.getSubtype(); if (requestedSubtype.equals(subtype)) matchCount += mediaRadix * 10; else if (!"*".equals(requestedSubtype)) continue; } Map<String, String> requestedParameters = requested.getParameters(); if (requestedParameters != null && requestedParameters.size() > 0) { if (!hasRequiredParameters(requestedParameters, parameters)) continue; matchCount += requestedParameters.size(); } if (matchCount > bestMatchCount) { bestMatchCount = matchCount; bestQuality = requestedMediaTypes.get(requested); bestRequestMediaType = requested; } else if (matchCount == bestMatchCount) { QualityValue qualityValue = requestedMediaTypes.get(requested); if (bestQuality.compareTo(qualityValue) < 0) { bestQuality = qualityValue; bestRequestMediaType = requested; } } } if (!bestQuality.isAcceptable()) return false; quality.setMediaTypeQualityValue(bestQuality); quality.setRequestMediaType(bestRequestMediaType); return true; } private boolean hasRequiredParameters(Map<String, String> required, Map<String, String> available) { if (available == null) { return false; } for (Entry<String, String> requiredEntry : required.entrySet()) { String name = requiredEntry.getKey(); String value = requiredEntry.getValue(); String availableValue = available.get(name); if (availableValue == null && "charset".equals(name)) { if (requestedCharacterSets != null && !requestedCharacterSets.containsKey(null) && !requestedCharacterSets.containsKey(value)) return false; } else if (!value.equals(availableValue)) return false; } return true; } private boolean applyCharacterSet(Variant option, VariantQuality quality) { if (requestedCharacterSets == null) return true; MediaType mediaType = option.getMediaType(); if (mediaType == null) return true; String charsetParameter = mediaType.getParameters().get("charset"); if (charsetParameter == null) return true; QualityValue value = requestedCharacterSets.get(charsetParameter); if (value == null) // try wildcard value = requestedCharacterSets.get(null); if (value == null) // no match return false; if (!value.isAcceptable()) return false; quality.setCharacterSetQualityValue(value); return true; } private boolean applyEncoding(Variant option, VariantQuality quality) { if (requestedEncodings == null) return true; String encoding = option.getEncoding(); if (encoding == null) return true; QualityValue value = requestedEncodings.get(encoding); if (value == null) // try wildcard value = requestedEncodings.get(null); if (value == null) // no match return false; if (!value.isAcceptable()) return false; quality.setEncodingQualityValue(value); return true; } private boolean hasCountry(Locale locale) { return locale.getCountry() != null && !"".equals(locale.getCountry().trim()); } private boolean applyLanguage(Variant option, VariantQuality quality) { if (requestedLanguages == null) return true; Locale language = option.getLanguage(); if (language == null) return true; QualityValue value = null; for (Entry<Locale, QualityValue> entry : requestedLanguages.entrySet()) { Locale locale = entry.getKey(); QualityValue qualityValue = entry.getValue(); if (locale == null) continue; if (locale.getLanguage().equalsIgnoreCase(language.getLanguage())) { if (hasCountry(locale) && hasCountry(language)) { if (locale.getCountry().equalsIgnoreCase(language.getCountry())) { value = qualityValue; break; } else { continue; } } else if (hasCountry(locale) == hasCountry(language)) { value = qualityValue; break; } else { value = qualityValue; // might be a better match so re-loop } } } if (value == null) // try wildcard value = requestedLanguages.get(null); if (value == null) // no match return false; if (!value.isAcceptable()) return false; quality.setLanguageQualityValue(value); return true; } }