feat: support for jdk 21 (#265)

Author: alexey-anufriev

.github/workflows/ci.yaml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-latest, windows-latest ]
-        java: [ 8.0.345, 8, 11, 17, 20 ]
+        java: [ 8.0.345, 8, 11, 17, 20, 21 ]
       fail-fast: false
       max-parallel: 64
     name: Fast CI on Java ${{ matrix.java }} OS ${{ matrix.os }}

.github/workflows/strong_ci.yaml

@@ -27,6 +27,7 @@ jobs:
             11
             17
             20
+            21
           distribution: zulu
           cache: maven
 

README.md

@@ -27,7 +27,7 @@
 Java Dns Cache Manipulator(`DCM`) contains 2 subprojects:
 
 - [**`DCM` Library**](library)  
-  A tiny 0-dependency thread-safe lib for setting/viewing dns programmatically without touching host file, make unit/integration test portable. Support `Java 8~20`, support `IPv6`.
+  A tiny 0-dependency thread-safe lib for setting/viewing dns programmatically without touching host file, make unit/integration test portable. Support `Java 8~21`, support `IPv6`.
 - [**`DCM` Tool**](tool)  
   A tiny tool for setting/viewing dns of running JVM processes.
 

library/pom.xml

@@ -14,7 +14,7 @@
 	<description>
 		🌏 a tiny 0-dependency thread-safe Java™ lib
 		for setting/viewing dns programmatically without touching host file,
-		make unit/integration test portable. support Java 8~20, support IPv6.
+		make unit/integration test portable. support Java 8~21, support IPv6.
 	</description>
 	<url>https://github.com/alibaba/java-dns-cache-manipulator</url>
 	<inceptionYear>2015</inceptionYear>

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

@@ -80,7 +80,15 @@ private static Object newCachedAddresses(String host, String[] ips, long expirat
             // double check
             if (constructorOfInetAddress$CachedAddresses != null) return constructorOfInetAddress$CachedAddresses;
 
-            final Class<?> clazz = Class.forName(inetAddress$CachedAddresses_ClassName);
+            Class<?> clazz;
+
+            try {
+                clazz = Class.forName(inetAddress$CachedAddresses_ClassName);
+            } catch (ClassNotFoundException e) {
+                // jdk 21 support
+                // due to https://github.com/openjdk/jdk/commit/8b127262a3dff9c4420945e902f6a688f8d05e2e
+                clazz = Class.forName(inetAddress$CachedLookup_ClassName);
+            }
 
             // InetAddress.CacheEntry has only one constructor:
             //
@@ -89,6 +97,8 @@ private static Object newCachedAddresses(String host, String[] ips, long expirat
             //   https://hg.openjdk.java.net/jdk9/jdk9/jdk/file/65464a307408/src/java.base/share/classes/java/net/InetAddress.java#l783
             // code in jdk 11:
             //   https://hg.openjdk.java.net/jdk/jdk11/file/1ddf9a99e4ad/src/java.base/share/classes/java/net/InetAddress.java#l787
+            // code in jdk 21:
+            //   https://github.com/openjdk/jdk/blob/jdk-21-ga/src/java.base/share/classes/java/net/InetAddress.java#L979
             final Constructor<?> constructor = clazz.getDeclaredConstructors()[0];
             constructor.setAccessible(true);
 
@@ -235,7 +245,10 @@ public static DnsCache listInetAddressCache()
 
         final InetAddress[] inetAddresses;
         final long expiration;
-        if (addressesClassName.equals(inetAddress$CachedAddresses_ClassName)) {
+        if (addressesClassName.equals(inetAddress$CachedAddresses_ClassName)
+                // jdk 21 support
+                || addressesClassName.equals(inetAddress$CachedLookup_ClassName)) {
+
             inetAddresses = (InetAddress[]) inetAddressesFieldOfInetAddress$CacheAddress.get(addresses);
 
             long expiryTimeNanos = expiryTimeFieldOfInetAddress$CacheAddress.getLong(addresses);
@@ -254,6 +267,7 @@ public static DnsCache listInetAddressCache()
     }
 
     private static final String inetAddress$CachedAddresses_ClassName = "java.net.InetAddress$CachedAddresses";
+    private static final String inetAddress$CachedLookup_ClassName = "java.net.InetAddress$CachedLookup";
     private static final String inetAddress$NameServiceAddresses_ClassName = "java.net.InetAddress$NameServiceAddresses";
 
     // Fields of InetAddress$CachedAddresses
@@ -275,7 +289,14 @@ private static void initFieldsOfAddresses() throws ClassNotFoundException, NoSuc
             ///////////////////////////////////////////////
             // Fields of InetAddress$CachedAddresses
             ///////////////////////////////////////////////
-            final Class<?> cachedAddresses_Class = Class.forName(inetAddress$CachedAddresses_ClassName);
+            Class<?> cachedAddresses_Class;
+
+            try {
+                cachedAddresses_Class = Class.forName(inetAddress$CachedAddresses_ClassName);
+            } catch (ClassNotFoundException e) {
+                // jdk 21 support
+                cachedAddresses_Class = Class.forName(inetAddress$CachedLookup_ClassName);
+            }
 
             final Field inetAddressesFiled = cachedAddresses_Class.getDeclaredField("inetAddresses");
             inetAddressesFiled.setAccessible(true);

scripts/integration_test

@@ -55,6 +55,7 @@ readonly CI_JDKS=(
   "$default_build_jdk_version"
   17
   20
+  21
 )
 
 # here use `install` and `-D performRelease` intended

tool/pom.xml

@@ -13,7 +13,7 @@
 	<name>Java Dns Cache Manipulator(DCM) Tool</name>
 	<description>
 		🌏 a tiny tool for setting/viewing dns of running JVM process.
-		support Java 8~20, support IPv6.
+		support Java 8~21, support IPv6.
 	</description>
 	<url>https://github.com/alibaba/java-dns-cache-manipulator</url>
 	<inceptionYear>2015</inceptionYear>