Replace anonymous class with method reference (apache#2929)

* Replace anonymous class with method reference

* Revert changes as per @beiwei30 code review

dubbo-common/src/main/java/org/apache/dubbo/common/json/GenericJSONConverter.java

@@ -130,12 +130,7 @@ public void encode(Object obj, JSONWriter jb) throws IOException {
         GlobalEncoderMap.put(Date.class, e);
 
         // init decoder map.
-        Decoder d = new Decoder() {
-            @Override
-            public Object decode(Object jv) {
-                return jv.toString();
-            }
-        };
+        Decoder d = Object::toString;
         GlobalDecoderMap.put(String.class, d);
 
         d = new Decoder() {

dubbo-common/src/test/java/org/apache/dubbo/common/concurrent/CompletableFutureTaskTest.java

@@ -78,12 +78,7 @@ public void testListener() throws InterruptedException {
 
         }, executor);
         final CountDownLatch countDownLatch = new CountDownLatch(1);
-        completableFuture.thenRunAsync(new Runnable() {
-            @Override
-            public void run() {
-                countDownLatch.countDown();
-            }
-        });
+        completableFuture.thenRunAsync(countDownLatch::countDown);
         countDownLatch.await();
     }
 

dubbo-common/src/test/java/org/apache/dubbo/common/concurrent/ExecutionListTest.java

@@ -54,12 +54,7 @@ public void testAddRunnableToExecutor() {
     @Test
     public void testExecuteRunnableWithDefaultExecutor() throws InterruptedException {
         final CountDownLatch countDownLatch = new CountDownLatch(1);
-        this.executionList.add(new Runnable() {
-            @Override
-            public void run() {
-                countDownLatch.countDown();
-            }
-        }, null);
+        this.executionList.add(countDownLatch::countDown, null);
 
         this.executionList.execute();
         countDownLatch.await();

dubbo-common/src/test/java/org/apache/dubbo/common/threadlocal/InternalThreadLocalTest.java

@@ -49,12 +49,7 @@ protected Integer initialValue() throws Exception {
         };
 
         for (int i = 0; i < THREADS; i++) {
-            Thread t = new Thread(new Runnable() {
-                @Override
-                public void run() {
-                    internalThreadLocal.get();
-                }
-            });
+            Thread t = new Thread(internalThreadLocal::get);
             t.start();
         }
 

dubbo-config/dubbo-config-api/src/main/java/org/apache/dubbo/config/ServiceConfig.java

@@ -206,12 +206,7 @@ public synchronized void export() {
         }
 
         if (delay != null && delay > 0) {
-            delayExportExecutor.schedule(new Runnable() {
-                @Override
-                public void run() {
-                    doExport();
-                }
-            }, delay, TimeUnit.MILLISECONDS);
+            delayExportExecutor.schedule(this::doExport, delay, TimeUnit.MILLISECONDS);
         } else {
             doExport();
         }

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/support/AbstractRegistry.java

@@ -245,12 +245,7 @@ public List<URL> lookup(URL url) {
             }
         } else {
             final AtomicReference<List<URL>> reference = new AtomicReference<List<URL>>();
-            NotifyListener listener = new NotifyListener() {
-                @Override
-                public void notify(List<URL> urls) {
-                    reference.set(urls);
-                }
-            };
+            NotifyListener listener = reference::set;
             subscribe(url, listener); // Subscribe logic guarantees the first notify to return
             List<URL> urls = reference.get();
             if (urls != null && !urls.isEmpty()) {

dubbo-remoting/dubbo-remoting-zookeeper/src/main/java/org/apache/dubbo/remoting/zookeeper/zkclient/ZkclientZookeeperClient.java

@@ -114,13 +114,7 @@ public void doClose() {
 
     @Override
     public IZkChildListener createTargetChildListener(String path, final ChildListener listener) {
-        return new IZkChildListener() {
-            @Override
-            public void handleChildChange(String parentPath, List<String> currentChilds)
-                    throws Exception {
-                listener.childChanged(parentPath, currentChilds);
-            }
-        };
+        return listener::childChanged;
     }
 
     @Override

dubbo-rpc/dubbo-rpc-rmi/src/main/java/org/apache/dubbo/rpc/protocol/rmi/RmiProtocol.java

@@ -22,12 +22,9 @@
 import org.apache.dubbo.rpc.RpcException;
 import org.apache.dubbo.rpc.protocol.AbstractProxyProtocol;
 
-import org.aopalliance.intercept.MethodInvocation;
 import org.springframework.remoting.RemoteAccessException;
 import org.springframework.remoting.rmi.RmiProxyFactoryBean;
 import org.springframework.remoting.rmi.RmiServiceExporter;
-import org.springframework.remoting.support.RemoteInvocation;
-import org.springframework.remoting.support.RemoteInvocationFactory;
 
 import java.io.IOException;
 import java.net.SocketTimeoutException;
@@ -80,12 +77,7 @@ protected <T> T doRefer(final Class<T> serviceType, final URL url) throws RpcExc
         // RMI needs extra parameter since it uses customized remote invocation object
         if (url.getParameter(Constants.DUBBO_VERSION_KEY, Version.getProtocolVersion()).equals(Version.getProtocolVersion())) {
             // Check dubbo version on provider, this feature only support
-            rmiProxyFactoryBean.setRemoteInvocationFactory(new RemoteInvocationFactory() {
-                @Override
-                public RemoteInvocation createRemoteInvocation(MethodInvocation methodInvocation) {
-                    return new RmiRemoteInvocation(methodInvocation);
-                }
-            });
+            rmiProxyFactoryBean.setRemoteInvocationFactory(RmiRemoteInvocation::new);
         }
         rmiProxyFactoryBean.setServiceUrl(url.toIdentityString());
         rmiProxyFactoryBean.setServiceInterface(serviceType);