Refactor VersionStrategy in WebFlux

Collapse the base interface VersionPathStrategy into its extension
VersionStrategy and then turn the prefix nad fliename based
implementations into abstract base classes (vs delegate strategies).

It is simpler to have one VersionStrategy hierarchy vs that plus a
separate VersionPathStrategy as a delegate. In practice each
VersionStrategy is suited to be prefix or filename based. Also none
of our code cares about the distinction between those two interfaces.

Author: rstoyanchev

spring-webflux/src/main/java/org/springframework/web/reactive/resource/AbstractFileNameVersionStrategy.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2002-2016 the original author or authors.
+ *
+ * Licensed 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.springframework.web.reactive.resource;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.util.StringUtils;
+
+/**
+ * Abstract base class for filename suffix based {@link VersionStrategy}
+ * implementations, e.g. "static/myresource-version.js"
+ *
+ * @author Rossen Stoyanchev
+ * @author Brian Clozel
+ * @since 5.0
+ */
+public abstract class AbstractFileNameVersionStrategy implements VersionStrategy {
+
+	protected final Log logger = LogFactory.getLog(getClass());
+
+	private static final Pattern pattern = Pattern.compile("-(\\S*)\\.");
+
+
+	@Override
+	public String extractVersion(String requestPath) {
+		Matcher matcher = pattern.matcher(requestPath);
+		if (matcher.find()) {
+			String match = matcher.group(1);
+			return (match.contains("-") ? match.substring(match.lastIndexOf('-') + 1) : match);
+		}
+		else {
+			return null;
+		}
+	}
+
+	@Override
+	public String removeVersion(String requestPath, String version) {
+		return StringUtils.delete(requestPath, "-" + version);
+	}
+
+	@Override
+	public String addVersion(String requestPath, String version) {
+		String baseFilename = StringUtils.stripFilenameExtension(requestPath);
+		String extension = StringUtils.getFilenameExtension(requestPath);
+		return (baseFilename + '-' + version + '.' + extension);
+	}
+
+}

spring-webflux/src/main/java/org/springframework/web/reactive/resource/AbstractPrefixVersionStrategy.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2002-2016 the original author or authors.
+ *
+ * Licensed 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.springframework.web.reactive.resource;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.util.Assert;
+
+/**
+ * Abstract base class for {@link VersionStrategy} implementations that insert
+ * a prefix into the URL path, e.g. "version/static/myresource.js".
+ *
+ * @author Rossen Stoyanchev
+ * @author Brian Clozel
+ * @since 5.0
+ */
+public abstract class AbstractPrefixVersionStrategy implements VersionStrategy {
+
+	protected final Log logger = LogFactory.getLog(getClass());
+
+
+	private final String prefix;
+
+
+	protected AbstractPrefixVersionStrategy(String version) {
+		Assert.hasText(version, "'version' must not be empty");
+		this.prefix = version;
+	}
+
+
+	public String getPrefix() {
+		return this.prefix;
+	}
+
+
+	@Override
+	public String extractVersion(String requestPath) {
+		return requestPath.startsWith(this.prefix) ? this.prefix : null;
+	}
+
+	@Override
+	public String removeVersion(String requestPath, String version) {
+		return requestPath.substring(this.prefix.length());
+	}
+
+	@Override
+	public String addVersion(String path, String version) {
+		if (path.startsWith(".")) {
+			return path;
+		}
+		else if (this.prefix.endsWith("/") || path.startsWith("/")) {
+			return this.prefix + path;
+		}
+		else {
+			return this.prefix + '/' + path;
+		}
+	}
+
+}

spring-webflux/src/main/java/org/springframework/web/reactive/resource/AbstractVersionStrategy.java

@@ -31,12 +31,7 @@
  * @since 5.0
  * @see VersionResourceResolver
  */
-public class ContentVersionStrategy extends AbstractVersionStrategy {
-
-
-	public ContentVersionStrategy() {
-		super(new FileNameVersionPathStrategy());
-	}
+public class ContentVersionStrategy extends AbstractFileNameVersionStrategy {
 
 
 	@Override

spring-webflux/src/main/java/org/springframework/web/reactive/resource/ContentVersionStrategy.java

@@ -31,24 +31,21 @@
  * @since 5.0
  * @see VersionResourceResolver
  */
-public class FixedVersionStrategy extends AbstractVersionStrategy {
-
-	private final String version;
+public class FixedVersionStrategy extends AbstractPrefixVersionStrategy {
 
 
 	/**
 	 * Create a new FixedVersionStrategy with the given version string.
 	 * @param version the fixed version string to use
 	 */
 	public FixedVersionStrategy(String version) {
-		super(new PrefixVersionPathStrategy(version));
-		this.version = version;
+		super(version);
 	}
 
 
 	@Override
 	public String getResourceVersion(Resource resource) {
-		return this.version;
+		return getPrefix();
 	}
 
 }