Code review (apache#3094)

* movde compareTo into Configurator as a default method

* adjust javado

* optimize diamond

* polish the code

Author: beiwei30

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/Configurator.java

@@ -35,32 +35,36 @@
 public interface Configurator extends Comparable<Configurator> {
 
     /**
-     * get the configurator url.
+     * Get the configurator url.
      *
      * @return configurator url.
      */
     URL getUrl();
 
     /**
      * Configure the provider url.
-     * O
      *
-     * @param url - old rovider url.
+     * @param url - old provider url.
      * @return new provider url.
      */
     URL configure(URL url);
 
 
     /**
-     * Convert override urls to map for use when re-refer.
-     * Send all rules every time, the urls will be reassembled and calculated
+     * Convert override urls to map for use when re-refer. Send all rules every time, the urls will be reassembled and
+     * calculated
      *
-     * @param urls Contract:
-     *             </br>1.override://0.0.0.0/...( or override://ip:port...?anyhost=true)&para1=value1... means global rules (all of the providers take effect)
-     *             </br>2.override://ip:port...?anyhost=false Special rules (only for a certain provider)
-     *             </br>3.override:// rule is not supported... ,needs to be calculated by registry itself.
-     *             </br>4.override://0.0.0.0/ without parameters means clearing the override
-     * @return
+     * URL contract:
+     * <ol>
+     * <li>override://0.0.0.0/...( or override://ip:port...?anyhost=true)&para1=value1... means global rules
+     * (all of the providers take effect)</li>
+     * <li>override://ip:port...?anyhost=false Special rules (only for a certain provider)</li>
+     * <li>override:// rule is not supported... ,needs to be calculated by registry itself</li>
+     * <li>override://0.0.0.0/ without parameters means clearing the override</li>
+     * </ol>
+     *
+     * @param urls URL list to convert
+     * @return converted configurator list
      */
     static Optional<List<Configurator>> toConfigurators(List<URL> urls) {
         if (CollectionUtils.isEmpty(urls)) {
@@ -70,13 +74,13 @@ static Optional<List<Configurator>> toConfigurators(List<URL> urls) {
         ConfiguratorFactory configuratorFactory = ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class)
                 .getAdaptiveExtension();
 
-        List<Configurator> configurators = new ArrayList<Configurator>(urls.size());
+        List<Configurator> configurators = new ArrayList<>(urls.size());
         for (URL url : urls) {
             if (Constants.EMPTY_PROTOCOL.equals(url.getProtocol())) {
                 configurators.clear();
                 break;
             }
-            Map<String, String> override = new HashMap<String, String>(url.getParameters());
+            Map<String, String> override = new HashMap<>(url.getParameters());
             //The anyhost parameter of override may be added automatically, it can't change the judgement of changing url
             override.remove(Constants.ANYHOST_KEY);
             if (override.size() == 0) {
@@ -88,4 +92,25 @@ static Optional<List<Configurator>> toConfigurators(List<URL> urls) {
         Collections.sort(configurators);
         return Optional.of(configurators);
     }
+
+    /**
+     * Sort by host, then by priority
+     * 1. the url with a specific host ip should have higher priority than 0.0.0.0
+     * 2. if two url has the same host, compare by priority value；
+     */
+    default int compareTo(Configurator o) {
+        if (o == null) {
+            return -1;
+        }
+
+        int ipCompare = getUrl().getHost().compareTo(o.getUrl().getHost());
+        // host is the same, sort by priority
+        if (ipCompare == 0) {
+            int i = getUrl().getParameter(Constants.PRIORITY_KEY, 0);
+            int j = o.getUrl().getParameter(Constants.PRIORITY_KEY, 0);
+            return Integer.compare(i, j);
+        } else {
+            return ipCompare;
+        }
+    }
 }

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/configurator/AbstractConfigurator.java

@@ -131,32 +131,6 @@ private URL configureIfMatch(String host, URL url) {
         return url;
     }
 
-    /**
-     * Sort by host, priority
-     * 1. the url with a specific host ip should have higher priority than 0.0.0.0
-     * 2. if two url has the same host, compare by priority value；
-     *
-     * @param o
-     * @return
-     */
-    @Override
-    public int compareTo(Configurator o) {
-        if (o == null) {
-            return -1;
-        }
-
-        int ipCompare = getUrl().getHost().compareTo(o.getUrl().getHost());
-        if (ipCompare == 0) {//host is the same, sort by priority
-            int i = getUrl().getParameter(Constants.PRIORITY_KEY, 0),
-                    j = o.getUrl().getParameter(Constants.PRIORITY_KEY, 0);
-            return Integer.compare(i, j);
-        } else {
-            return ipCompare;
-        }
-
-
-    }
-
     protected abstract URL doConfigure(URL currentUrl, URL configUrl);
 
 }