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package org.apache.any23.servlet.conneg; |
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import java.util.ArrayList; |
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import java.util.Collection; |
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import java.util.Collections; |
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import java.util.Iterator; |
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import java.util.List; |
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import java.util.regex.Pattern; |
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30 | 0 | public class ContentTypeNegotiator { |
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32 | 0 | private List<VariantSpec> variantSpecs = new ArrayList<VariantSpec>(); |
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34 | 0 | private List<MediaRangeSpec> defaultAcceptRanges = Collections.singletonList(MediaRangeSpec.parseRange("*/*")); |
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36 | 0 | private Collection<AcceptHeaderOverride> userAgentOverrides = new ArrayList<AcceptHeaderOverride>(); |
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38 | 0 | protected ContentTypeNegotiator(){} |
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public MediaRangeSpec getBestMatch(String accept) { |
48 | 0 | return getBestMatch(accept, null); |
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} |
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public MediaRangeSpec getBestMatch(String accept, String userAgent) { |
61 | 0 | if (userAgent == null) { |
62 | 0 | userAgent = ""; |
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} |
64 | 0 | Iterator<AcceptHeaderOverride> it = userAgentOverrides.iterator(); |
65 | 0 | String overriddenAccept = accept; |
66 | 0 | while (it.hasNext()) { |
67 | 0 | AcceptHeaderOverride override = it.next(); |
68 | 0 | if (override.matches(accept, userAgent)) { |
69 | 0 | overriddenAccept = override.getReplacement(); |
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} |
71 | 0 | } |
72 | 0 | return new Negotiation(toAcceptRanges(overriddenAccept)).negotiate(); |
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} |
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protected VariantSpec addVariant(String mediaType) { |
76 | 0 | VariantSpec result = new VariantSpec(mediaType); |
77 | 0 | variantSpecs.add(result); |
78 | 0 | return result; |
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} |
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protected void setDefaultAccept(String accept) { |
87 | 0 | this.defaultAcceptRanges = MediaRangeSpec.parseAccept(accept); |
88 | 0 | } |
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protected void addUserAgentOverride( |
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Pattern userAgentString, |
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String originalAcceptHeader, |
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String newAcceptHeader |
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) { |
106 | 0 | this.userAgentOverrides.add( |
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new AcceptHeaderOverride(userAgentString, originalAcceptHeader, newAcceptHeader) |
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); |
109 | 0 | } |
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private List<MediaRangeSpec> toAcceptRanges(String accept) { |
112 | 0 | if (accept == null) { |
113 | 0 | return defaultAcceptRanges; |
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} |
115 | 0 | List<MediaRangeSpec> result = MediaRangeSpec.parseAccept(accept); |
116 | 0 | if (result.isEmpty()) { |
117 | 0 | return defaultAcceptRanges; |
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} |
119 | 0 | return result; |
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} |
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122 | 0 | protected class VariantSpec { |
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private MediaRangeSpec type; |
125 | 0 | private List<MediaRangeSpec> aliases = new ArrayList<MediaRangeSpec>(); |
126 | 0 | private boolean isDefault = false; |
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128 | 0 | public VariantSpec(String mediaType) { |
129 | 0 | type = MediaRangeSpec.parseType(mediaType); |
130 | 0 | } |
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public VariantSpec addAliasMediaType(String mediaType) { |
133 | 0 | aliases.add(MediaRangeSpec.parseType(mediaType)); |
134 | 0 | return this; |
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} |
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public void makeDefault() { |
138 | 0 | isDefault = true; |
139 | 0 | } |
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public MediaRangeSpec getMediaType() { |
142 | 0 | return type; |
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} |
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public boolean isDefault() { |
146 | 0 | return isDefault; |
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} |
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public List<MediaRangeSpec> getAliases() { |
150 | 0 | return aliases; |
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} |
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} |
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private class Negotiation { |
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private final List<MediaRangeSpec> ranges; |
157 | 0 | private MediaRangeSpec bestMatchingVariant = null; |
158 | 0 | private MediaRangeSpec bestDefaultVariant = null; |
159 | 0 | private double bestMatchingQuality = 0; |
160 | 0 | private double bestDefaultQuality = 0; |
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162 | 0 | Negotiation(List<MediaRangeSpec> ranges) { |
163 | 0 | this.ranges = ranges; |
164 | 0 | } |
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MediaRangeSpec negotiate() { |
167 | 0 | Iterator<VariantSpec> it = variantSpecs.iterator(); |
168 | 0 | while (it.hasNext()) { |
169 | 0 | VariantSpec variant = it.next(); |
170 | 0 | if (variant.isDefault) { |
171 | 0 | evaluateDefaultVariant(variant.getMediaType()); |
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} |
173 | 0 | evaluateVariant(variant.getMediaType()); |
174 | 0 | Iterator<MediaRangeSpec> aliasIt = variant.getAliases().iterator(); |
175 | 0 | while (aliasIt.hasNext()) { |
176 | 0 | MediaRangeSpec alias = aliasIt.next(); |
177 | 0 | evaluateVariantAlias(alias, variant.getMediaType()); |
178 | 0 | } |
179 | 0 | } |
180 | 0 | return (bestMatchingVariant == null) ? bestDefaultVariant : bestMatchingVariant; |
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} |
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private void evaluateVariantAlias(MediaRangeSpec variant, MediaRangeSpec isAliasFor) { |
184 | 0 | if (variant.getBestMatch(ranges) == null) return; |
185 | 0 | double q = variant.getBestMatch(ranges).getQuality(); |
186 | 0 | if (q * variant.getQuality() > bestMatchingQuality) { |
187 | 0 | bestMatchingVariant = isAliasFor; |
188 | 0 | bestMatchingQuality = q * variant.getQuality(); |
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} |
190 | 0 | } |
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private void evaluateVariant(MediaRangeSpec variant) { |
193 | 0 | evaluateVariantAlias(variant, variant); |
194 | 0 | } |
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private void evaluateDefaultVariant(MediaRangeSpec variant) { |
197 | 0 | if (variant.getQuality() > bestDefaultQuality) { |
198 | 0 | bestDefaultVariant = variant; |
199 | 0 | bestDefaultQuality = 0.00001 * variant.getQuality(); |
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} |
201 | 0 | } |
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} |
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private class AcceptHeaderOverride { |
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private Pattern userAgentPattern; |
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private String original; |
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private String replacement; |
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211 | 0 | AcceptHeaderOverride(Pattern userAgentPattern, String original, String replacement) { |
212 | 0 | this.userAgentPattern = userAgentPattern; |
213 | 0 | this.original = original; |
214 | 0 | this.replacement = replacement; |
215 | 0 | } |
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boolean matches(String acceptHeader) { |
218 | 0 | return matches(acceptHeader, null); |
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} |
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boolean matches(String acceptHeader, String userAgentHeader) { |
222 | 0 | return (userAgentPattern == null |
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|| userAgentPattern.matcher(userAgentHeader).find()) |
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&& (original == null || original.equals(acceptHeader)); |
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} |
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String getReplacement() { |
228 | 0 | return replacement; |
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} |
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} |
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} |