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package org.apache.juneau.encoders; | |
import static org.apache.juneau.internal.CollectionUtils.*; | |
import java.util.*; | |
import java.util.concurrent.*; | |
import org.apache.juneau.http.*; | |
/** | |
* Represents the group of {@link Encoder encoders} keyed by codings. | |
* | |
* <h5 class='topic'>Description</h5> | |
* | |
* Maintains a set of encoders and the codings that they can handle. | |
* | |
* <p> | |
* The {@link #getEncoderMatch(String)} and {@link #getEncoder(String)} methods are then used to find appropriate | |
* encoders for specific <c>Accept-Encoding</c> and <c>Content-Encoding</c> header values. | |
* | |
* <h5 class='topic'>Match ordering</h5> | |
* | |
* Encoders are matched against <c>Accept-Encoding</c> strings in the order they exist in this group. | |
* | |
* <p> | |
* Adding new entries will cause the entries to be prepended to the group. | |
* This allows for previous encoders to be overridden through subsequent calls. | |
* | |
* <p> | |
* For example, calling <code>groupBuilder.append(E1.<jk>class</jk>,E2.<jk>class</jk>).append(E3.<jk>class</jk>, | |
* E4.<jk>class</jk>)</code> will result in the order <c>E3, E4, E1, E2</c>. | |
* | |
* <h5 class='section'>Example:</h5> | |
* <p class='bcode w800'> | |
* <jc>// Create an encoder group with support for gzip compression.</jc> | |
* EncoderGroup g = EncoderGroup.<jsm>create</jsm>().append(GzipEncoder.<jk>class</jk>).build(); | |
* | |
* <jc>// Should return "gzip"</jc> | |
* String matchedCoding = g.findMatch(<js>"compress;q=1.0, gzip;q=0.8, identity;q=0.5, *;q=0"</js>); | |
* | |
* <jc>// Get the encoder</jc> | |
* IEncoder encoder = g.getEncoder(matchedCoding); | |
* </p> | |
*/ | |
public final class EncoderGroup { | |
/** | |
* A default encoder group consisting of identity and G-Zip encoding. | |
*/ | |
public static final EncoderGroup DEFAULT = create().append(IdentityEncoder.class, GzipEncoder.class).build(); | |
// Maps Accept-Encoding headers to matching encoders. | |
private final ConcurrentHashMap<String,EncoderMatch> cache = new ConcurrentHashMap<>(); | |
private final String[] encodings; | |
private final List<String> encodingsList; | |
private final Encoder[] encodingsEncoders; | |
private final List<Encoder> encoders; | |
/** | |
* Instantiates a new clean-slate {@link EncoderGroupBuilder} object. | |
* | |
* <p> | |
* This is equivalent to simply calling <code><jk>new</jk> EncoderGroupBuilder()</code>. | |
* | |
* @return A new {@link EncoderGroupBuilder} object. | |
*/ | |
public static EncoderGroupBuilder create() { | |
return new EncoderGroupBuilder(); | |
} | |
/** | |
* Returns a builder that's a copy of the settings on this encoder group. | |
* | |
* @return A new {@link EncoderGroupBuilder} initialized to this group. | |
*/ | |
public EncoderGroupBuilder builder() { | |
return new EncoderGroupBuilder(this); | |
} | |
/** | |
* Constructor | |
* | |
* @param encoders The encoders to add to this group. | |
*/ | |
public EncoderGroup(Encoder[] encoders) { | |
this.encoders = immutableList(encoders); | |
List<String> lc = new ArrayList<>(); | |
List<Encoder> l = new ArrayList<>(); | |
for (Encoder e : encoders) { | |
for (String c: e.getCodings()) { | |
lc.add(c); | |
l.add(e); | |
} | |
} | |
this.encodings = lc.toArray(new String[lc.size()]); | |
this.encodingsList = unmodifiableList(lc); | |
this.encodingsEncoders = l.toArray(new Encoder[l.size()]); | |
} | |
/** | |
* Returns the coding string for the matching encoder that can handle the specified <c>Accept-Encoding</c> | |
* or <c>Content-Encoding</c> header value. | |
* | |
* <p> | |
* Returns <jk>null</jk> if no encoders can handle it. | |
* | |
* <p> | |
* This method is fully compliant with the RFC2616/14.3 and 14.11 specifications. | |
* | |
* @param acceptEncoding The <c>Accept-Encoding</c> or <c>Content-Encoding</c> value. | |
* @return The coding value (e.g. <js>"gzip"</js>). | |
*/ | |
public EncoderMatch getEncoderMatch(String acceptEncoding) { | |
EncoderMatch em = cache.get(acceptEncoding); | |
if (em != null) | |
return em; | |
AcceptEncoding ae = AcceptEncoding.forString(acceptEncoding); | |
int match = ae.findMatch(encodings); | |
if (match >= 0) { | |
em = new EncoderMatch(encodings[match], encodingsEncoders[match]); | |
cache.putIfAbsent(acceptEncoding, em); | |
} | |
return cache.get(acceptEncoding); | |
} | |
/** | |
* Returns the encoder registered with the specified coding (e.g. <js>"gzip"</js>). | |
* | |
* @param encoding The coding string. | |
* @return The encoder, or <jk>null</jk> if encoder isn't registered with that coding. | |
*/ | |
public Encoder getEncoder(String encoding) { | |
EncoderMatch em = getEncoderMatch(encoding); | |
return (em == null ? null : em.getEncoder()); | |
} | |
/** | |
* Returns the set of codings supported by all encoders in this group. | |
* | |
* @return An unmodifiable list of codings supported by all encoders in this group. Never <jk>null</jk>. | |
*/ | |
public List<String> getSupportedEncodings() { | |
return encodingsList; | |
} | |
/** | |
* Returns the encoders in this group. | |
* | |
* @return An unmodifiable list of encoders in this group. | |
*/ | |
public List<Encoder> getEncoders() { | |
return encoders; | |
} | |
} |