Add EncodingNegotiator

Author: Long9725

java/org/apache/coyote/CompressionConfig.java

@@ -274,7 +274,7 @@ public OutputFilterFactory useCompression(Request request, Response response, Li
                 return null;
             }
 
-            teFactory = negotiateTE(factories, tes);
+            teFactory = EncodingNegotiator.negotiateTE(factories, tes);
             if(teFactory != null) {
                 useTransferEncoding = true;
                 break;
@@ -308,7 +308,7 @@ public OutputFilterFactory useCompression(Request request, Response response, Li
                     return null;
                 }
 
-                selectedFactory = negotiateAcceptEncoding(factories, acceptEncodings);
+                selectedFactory = EncodingNegotiator.negotiateAcceptEncoding(factories, acceptEncodings);
                 if (selectedFactory != null) {
                     break;
                 }
@@ -350,74 +350,6 @@ public OutputFilterFactory useCompression(Request request, Response response, Li
         return selectedFactory;
     }
 
-    /**
-     * Negotiate the best encoding from TE header entries against available factories
-     */
-    private OutputFilterFactory negotiateTE(List<OutputFilterFactory> factories, List<TE> entries) {
-        OutputFilterFactory bestFactory = null;
-        double bestQuality = 0;
-        int bestServerPriority = Integer.MAX_VALUE;
-
-        for (int i = 0; i < factories.size(); i++) {
-            OutputFilterFactory factory = factories.get(i);
-            String factoryEncoding = factory.getEncodingName().toLowerCase(Locale.ENGLISH);
-
-            for (TE entry : entries) {
-                String entryEncoding = entry.getEncoding().toLowerCase(Locale.ENGLISH);
-                double quality = entry.getQuality();
-
-                if (quality <= 0) {
-                    continue;
-                }
-
-                if (factoryEncoding.equals(entryEncoding) || "*".equals(entryEncoding)) {
-                    if (quality > bestQuality || (quality == bestQuality && i < bestServerPriority)) {
-                        bestFactory = factory;
-                        bestQuality = quality;
-                        bestServerPriority = i;
-                    }
-                }
-            }
-        }
-
-        return bestFactory;
-    }
-
-    /**
-     * Negotiate the best encoding from Accept-Encoding entries against available factories.
-     */
-    private OutputFilterFactory negotiateAcceptEncoding(
-            List<OutputFilterFactory> factories,
-            List<AcceptEncoding> acceptEncodings) {
-        OutputFilterFactory bestFactory = null;
-        double bestQuality = 0;
-        int bestServerPriority = Integer.MAX_VALUE;
-
-        for (int i = 0; i < factories.size(); i++) {
-            OutputFilterFactory factory = factories.get(i);
-            String factoryEncoding = factory.getEncodingName().toLowerCase(Locale.ENGLISH);
-
-            for (AcceptEncoding ae : acceptEncodings) {
-                String aeEncoding = ae.getEncoding().toLowerCase(Locale.ENGLISH);
-                double quality = ae.getQuality();
-
-                if (quality <= 0) {
-                    continue;
-                }
-
-                if (factoryEncoding.equals(aeEncoding) || "*".equals(aeEncoding)) {
-                    if (quality > bestQuality || (quality == bestQuality && i < bestServerPriority)) {
-                        bestFactory = factory;
-                        bestQuality = quality;
-                        bestServerPriority = i;
-                    }
-                }
-            }
-        }
-
-        return bestFactory;
-    }
-
     /**
      * Checks if any entry in the string array starts with the specified value
      *

java/org/apache/coyote/EncodingNegotiator.java

@@ -0,0 +1,100 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.apache.coyote;
+
+import java.util.List;
+import java.util.Locale;
+import java.util.function.Function;
+import java.util.function.ToDoubleFunction;
+
+import org.apache.coyote.http11.filters.OutputFilterFactory;
+import org.apache.tomcat.util.http.parser.AcceptEncoding;
+import org.apache.tomcat.util.http.parser.TE;
+
+/**
+ * Utility class for negotiating transfer/content encodings using TE and
+ * Accept-Encoding headers.
+ */
+public class EncodingNegotiator {
+
+    /**
+     * Selects the best {@link OutputFilterFactory} for the HTTP {@code TE} header.
+     * <p>Rules:
+     * - Prefer the entry with the highest quality (q) value; entries with {@code q <= 0} are ignored.
+     * - Wildcard ({@code *}) matches any server factory.
+     * - On quality ties, prefer the factory with the lowest server priority (its index in {@code factories}).
+     * - Encoding name matching is case-insensitive.
+     *
+     * @param factories The available factories in server-priority order (index 0 is highest)
+     * @param entries    The parsed {@code TE} header entries
+     * @return The selected factory or {@code null} if no match
+     */
+    public static OutputFilterFactory negotiateTE(List<OutputFilterFactory> factories, List<TE> entries) {
+        return negotiateEncodings(factories, entries, TE::getEncoding, TE::getQuality);
+    }
+
+    /**
+     * Selects the best {@link OutputFilterFactory} for the HTTP {@code Accept-Encoding} header.
+     * <p>Rules:
+     * - Prefer the entry with the highest quality (q) value; entries with {@code q <= 0} are ignored.
+     * - Wildcard ({@code *}) matches any server factory.
+     * - On quality ties, prefer the factory with the lowest server priority (its index in {@code factories}).
+     * - Encoding name matching is case-insensitive.
+     *
+     * @param factories       The available factories in server-priority order (index 0 is highest)
+     * @param acceptEncodings The parsed {@code Accept-Encoding} entries
+     * @return The selected factory or {@code null} if no match
+     */
+    public static OutputFilterFactory negotiateAcceptEncoding(
+            List<OutputFilterFactory> factories, List<AcceptEncoding> acceptEncodings) {
+        return negotiateEncodings(factories, acceptEncodings, AcceptEncoding::getEncoding, AcceptEncoding::getQuality);
+    }
+
+    private static <T> OutputFilterFactory negotiateEncodings(
+            List<OutputFilterFactory> factories,
+            List<T> entries,
+            Function<T,String> encodingFn,
+            ToDoubleFunction<T> qualityFn) {
+        OutputFilterFactory bestFactory = null;
+        double bestQuality = 0;
+        int bestServerPriority = Integer.MAX_VALUE;
+
+        for (int i = 0; i < factories.size(); i++) {
+            OutputFilterFactory factory = factories.get(i);
+            String factoryEncoding = factory.getEncodingName().toLowerCase(Locale.ENGLISH);
+
+            for (T entry : entries) {
+                String entryEncoding = encodingFn.apply(entry).toLowerCase(Locale.ENGLISH);
+                double quality = qualityFn.applyAsDouble(entry);
+
+                if (quality <= 0) {
+                    continue;
+                }
+
+                if (factoryEncoding.equals(entryEncoding) || "*".equals(entryEncoding)) {
+                    if (quality > bestQuality || (quality == bestQuality && i < bestServerPriority)) {
+                        bestFactory = factory;
+                        bestQuality = quality;
+                        bestServerPriority = i;
+                    }
+                }
+            }
+        }
+
+        return bestFactory;
+    }
+}