! fix method_complexity InetAddressCacheUtilForJava8Minus#inetAddress$CacheEntry2DnsCacheEntry #65

Author: oldratlee

library/src/main/java/com/alibaba/dcm/internal/InetAddressCacheUtilForJava8Minus.java

@@ -221,7 +221,7 @@ public static DnsCache listInetAddressCache()
         return new DnsCache(convert(cache), convert(negativeCache));
     }
 
-    private static List<DnsCacheEntry> convert(Map<String, Object> cache) throws IllegalAccessException {
+    private static List<DnsCacheEntry> convert(Map<String, Object> cache) throws IllegalAccessException, ClassNotFoundException {
         final List<DnsCacheEntry> ret = new ArrayList<DnsCacheEntry>();
         for (Map.Entry<String, Object> entry : cache.entrySet()) {
             final String host = entry.getKey();
@@ -234,41 +234,8 @@ private static List<DnsCacheEntry> convert(Map<String, Object> cache) throws Ill
         return ret;
     }
 
-
-    private static volatile Field expirationFieldOfInetAddress$CacheEntry = null;
-    private static volatile Field addressesFieldOfInetAddress$CacheEntry = null;
-
-    private static DnsCacheEntry inetAddress$CacheEntry2DnsCacheEntry(String host, Object entry) throws IllegalAccessException {
-        if (expirationFieldOfInetAddress$CacheEntry == null || addressesFieldOfInetAddress$CacheEntry == null) {
-            synchronized (InetAddressCacheUtilForJava8Minus.class) {
-                if (expirationFieldOfInetAddress$CacheEntry == null || addressesFieldOfInetAddress$CacheEntry == null) { // double check
-                    Class<?> cacheEntryClass = entry.getClass();
-                    // InetAddress.CacheEntry has 2 filed:
-                    // - for jdk 6, address and expiration
-                    // - for jdk 7+, addresses(*renamed*!) and expiration
-                    // code in jdk 6:
-                    //   https://hg.openjdk.java.net/jdk6/jdk6/jdk/file/8deef18bb749/src/share/classes/java/net/InetAddress.java#l739
-                    // code in jdk 7:
-                    //   https://hg.openjdk.java.net/jdk7u/jdk7u/jdk/file/4dd5e486620d/src/share/classes/java/net/InetAddress.java#l742
-                    // code in jdk 8:
-                    //   https://hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/45e4e636b757/src/share/classes/java/net/InetAddress.java#l748
-                    final Field[] fields = cacheEntryClass.getDeclaredFields();
-                    for (Field field : fields) {
-                        final String name = field.getName();
-                        if (name.equals("expiration")) {
-                            field.setAccessible(true);
-                            expirationFieldOfInetAddress$CacheEntry = field;
-                        } else if (name.startsWith("address")) { // use startWith so works for jdk 6 and jdk 7+
-                            field.setAccessible(true);
-                            addressesFieldOfInetAddress$CacheEntry = field;
-                        } else {
-                            throw new IllegalStateException("JDK add new Field " + name +
-                                    " for class InetAddress.CacheEntry, report issue for dns-cache-manipulator lib!");
-                        }
-                    }
-                }
-            }
-        }
+    private static DnsCacheEntry inetAddress$CacheEntry2DnsCacheEntry(String host, Object entry) throws IllegalAccessException, ClassNotFoundException {
+        initFieldsOfInetAddress$CacheEntry();
 
         final long expiration = expirationFieldOfInetAddress$CacheEntry.getLong(entry);
 
@@ -278,6 +245,49 @@ private static List<DnsCacheEntry> convert(Map<String, Object> cache) throws Ill
         return new DnsCacheEntry(host, ips, expiration);
     }
 
+    /**
+     * {@link InetAddress.CacheEntry.expiration}
+     */
+    private static volatile Field expirationFieldOfInetAddress$CacheEntry = null;
+    /**
+     * {@link InetAddress.CacheEntry.expiration}
+     */
+    private static volatile Field addressesFieldOfInetAddress$CacheEntry = null;
+
+    private static void initFieldsOfInetAddress$CacheEntry() throws ClassNotFoundException {
+        if (expirationFieldOfInetAddress$CacheEntry != null && addressesFieldOfInetAddress$CacheEntry != null) return;
+
+        final Class<?> cacheEntryClass = Class.forName("java.net.InetAddress$CacheEntry");
+        synchronized (InetAddressCacheUtilForJava8Minus.class) {
+            // double check
+            if (expirationFieldOfInetAddress$CacheEntry != null && addressesFieldOfInetAddress$CacheEntry != null) return;
+
+            // InetAddress.CacheEntry has 2 filed:
+            // - for jdk 6, address and expiration
+            // - for jdk 7+, addresses(*renamed*!) and expiration
+            // code in jdk 6:
+            //   https://hg.openjdk.java.net/jdk6/jdk6/jdk/file/8deef18bb749/src/share/classes/java/net/InetAddress.java#l739
+            // code in jdk 7:
+            //   https://hg.openjdk.java.net/jdk7u/jdk7u/jdk/file/4dd5e486620d/src/share/classes/java/net/InetAddress.java#l742
+            // code in jdk 8:
+            //   https://hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/45e4e636b757/src/share/classes/java/net/InetAddress.java#l748
+            final Field[] fields = cacheEntryClass.getDeclaredFields();
+            for (Field field : fields) {
+                final String name = field.getName();
+                if (name.equals("expiration")) {
+                    field.setAccessible(true);
+                    expirationFieldOfInetAddress$CacheEntry = field;
+                } else if (name.startsWith("address")) { // use startWith so works for jdk 6 and jdk 7+
+                    field.setAccessible(true);
+                    addressesFieldOfInetAddress$CacheEntry = field;
+                } else {
+                    throw new IllegalStateException("JDK add new Field " + name +
+                            " for class InetAddress.CacheEntry, report issue for dns-cache-manipulator lib!");
+                }
+            }
+        }
+    }
+
     public static void clearInetAddressCache() throws NoSuchFieldException, IllegalAccessException, ClassNotFoundException {
         synchronized (getAddressCacheOfInetAddress()) {
             getCache().clear();