Java tutorial
package com.tdclighthouse.prototype.utils; import java.util.Collection; import java.util.Collections; import java.util.HashMap; import java.util.LinkedList; import java.util.List; import java.util.Map; import org.apache.commons.lang.StringUtils; import org.apache.commons.lang.math.NumberUtils; import org.apache.commons.lang3.builder.EqualsBuilder; import org.apache.commons.lang3.builder.HashCodeBuilder; /** * MIME-Type Parser * * This class provides basic functions for handling mime-types. It can handle * matching mime-types against a list of media-ranges. See section 14.1 of the * HTTP specification [RFC 2616] for a complete explanation. * * http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1 * * A port to Java of Joe Gregorio's MIME-Type Parser: * * http://code.google.com/p/mimeparse/ * * Ported by Tom Zellman <tzellman@gmail.com>. * * * This code has been adopted from and it is licensed under <a * href="http://opensource.org/licenses/mit-license.php">MIT License</a> * */ public final class MIMEParse { private static final String ASTERISK = "*"; /** * Parse results container */ protected static class ParseResults { String type; String subType; // !a dictionary of all the parameters for the media range Map<String, String> params; @Override public String toString() { StringBuilder s = new StringBuilder("('" + type + "', '" + subType + "', {"); for (String k : params.keySet()) { s.append("'" + k + "':'" + params.get(k) + "',"); } return s.append("})").toString(); } } /** * Carves up a mime-type and returns a ParseResults object * * For example, the media range 'application/xhtml;q=0.5' would get parsed * into: * * ('application', 'xhtml', {'q', '0.5'}) */ protected static ParseResults parseMimeType(String mimeType) { String[] parts = StringUtils.split(mimeType, ";"); ParseResults results = new ParseResults(); results.params = new HashMap<String, String>(); for (int i = 1; i < parts.length; ++i) { String p = parts[i]; String[] subParts = StringUtils.split(p, '='); if (subParts.length == 2) { results.params.put(subParts[0].trim(), subParts[1].trim()); } } String fullType = parts[0].trim(); // Java URLConnection class sends an Accept header that includes a // single "*" - Turn it into a legal wildcard. if (fullType.equals(ASTERISK)) { fullType = "*/*"; } String[] types = StringUtils.split(fullType, "/"); results.type = types[0].trim(); results.subType = types[1].trim(); return results; } /** * Carves up a media range and returns a ParseResults. * * For example, the media range 'application/*;q=0.5' would get parsed into: * * ('application', '*', {'q', '0.5'}) * * In addition this function also guarantees that there is a value for 'q' * in the params dictionary, filling it in with a proper default if * necessary. * * @param range */ protected static ParseResults parseMediaRange(String range) { ParseResults results = parseMimeType(range); String q = results.params.get("q"); float f = NumberUtils.toFloat(q, 1); if (StringUtils.isBlank(q) || f < 0 || f > 1) { results.params.put("q", "1"); } return results; } /** * Structure for holding a fitness/quality combo */ protected static class FitnessAndQuality implements Comparable<FitnessAndQuality> { int fitness; float quality; // optionally used String mimeType; public FitnessAndQuality(int fitness, float quality) { this.fitness = fitness; this.quality = quality; } public int compareTo(FitnessAndQuality o) { if (fitness == o.fitness) { if (quality == o.quality) { return 0; } else { return quality < o.quality ? -1 : 1; } } else { return fitness < o.fitness ? -1 : 1; } } @Override public boolean equals(Object obj) { boolean result; if (obj instanceof FitnessAndQuality) { FitnessAndQuality rhs = (FitnessAndQuality) obj; result = new EqualsBuilder().appendSuper(super.equals(obj)).append(fitness, rhs.fitness) .append(quality, rhs.quality).isEquals(); } else { result = false; } return result; } @Override public int hashCode() { return new HashCodeBuilder(93, 131).append(fitness).append(quality).toHashCode(); } } /** * Find the best match for a given mimeType against a list of media_ranges * that have already been parsed by MimeParse.parseMediaRange(). Returns a * tuple of the fitness value and the value of the 'q' quality parameter of * the best match, or (-1, 0) if no match was found. Just as for * quality_parsed(), 'parsed_ranges' must be a list of parsed media ranges. * * @param mimeType * @param parsedRanges */ protected static FitnessAndQuality fitnessAndQualityParsed(String mimeType, Collection<ParseResults> parsedRanges) { int bestFitness = -1; float bestFitQ = 0; ParseResults target = parseMediaRange(mimeType); for (ParseResults range : parsedRanges) { if ((target.type.equals(range.type) || range.type.equals(ASTERISK) || target.type.equals(ASTERISK)) && (target.subType.equals(range.subType) || range.subType.equals(ASTERISK) || target.subType.equals(ASTERISK))) { for (String k : target.params.keySet()) { int paramMatches = 0; if (!"q".equals(k) && range.params.containsKey(k) && target.params.get(k).equals(range.params.get(k))) { paramMatches++; } int fitness = (range.type.equals(target.type)) ? 100 : 0; fitness += (range.subType.equals(target.subType)) ? 10 : 0; fitness += paramMatches; if (fitness > bestFitness) { bestFitness = fitness; bestFitQ = NumberUtils.toFloat(range.params.get("q"), 0); } } } } return new FitnessAndQuality(bestFitness, bestFitQ); } /** * Find the best match for a given mime-type against a list of ranges that * have already been parsed by parseMediaRange(). Returns the 'q' quality * parameter of the best match, 0 if no match was found. This function * bahaves the same as quality() except that 'parsed_ranges' must be a list * of parsed media ranges. * * @param mimeType * @param parsedRanges * @return */ protected static float qualityParsed(String mimeType, Collection<ParseResults> parsedRanges) { return fitnessAndQualityParsed(mimeType, parsedRanges).quality; } /** * Returns the quality 'q' of a mime-type when compared against the * mediaRanges in ranges. For example: * * @param mimeType * @param parsedRanges */ public static float quality(String mimeType, String ranges) { List<ParseResults> results = new LinkedList<ParseResults>(); for (String r : StringUtils.split(ranges, ',')) { results.add(parseMediaRange(r)); } return qualityParsed(mimeType, results); } /** * Takes a list of supported mime-types and finds the best match for all the * media-ranges listed in header. The value of header must be a string that * conforms to the format of the HTTP Accept: header. The value of * 'supported' is a list of mime-types. * * MimeParse.bestMatch(Arrays.asList(new String[]{"application/xbel+xml", * "text/xml"}), "text/*;q=0.5,*; q=0.1") 'text/xml' * * @param supported * @param header * @return */ public static String bestMatch(Collection<String> supported, String header) { List<ParseResults> parseResults = new LinkedList<ParseResults>(); List<FitnessAndQuality> weightedMatches = new LinkedList<FitnessAndQuality>(); for (String r : StringUtils.split(header, ',')) { parseResults.add(parseMediaRange(r)); } for (String s : supported) { FitnessAndQuality fitnessAndQuality = fitnessAndQualityParsed(s, parseResults); fitnessAndQuality.mimeType = s; weightedMatches.add(fitnessAndQuality); } Collections.sort(weightedMatches); FitnessAndQuality lastOne = weightedMatches.get(weightedMatches.size() - 1); return NumberUtils.compare(lastOne.quality, 0) != 0 ? lastOne.mimeType : ""; } // hidden private MIMEParse() { } }