add Log4j2ContextFilter demo

pom.xml

@@ -76,6 +76,16 @@
 			<version>3.19.0-GA</version>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.apache.logging.log4j</groupId>
+			<artifactId>log4j-api</artifactId>
+			<version>2.3</version>
+		</dependency>
+		<dependency>
+			<groupId>org.apache.logging.log4j</groupId>
+			<artifactId>log4j-core</artifactId>
+			<version>2.3</version>
+		</dependency>
 		<!-- Testing frameworks and related dependencies -->
 		<dependency>
 			<groupId>junit</groupId>

src/test/java/log4j2/Log4j2ContextFilter.java

@@ -0,0 +1,68 @@
+package log4j2;
+
+import com.alibaba.mtc.MtContextRunnable;
+import com.alibaba.mtc.MtContextThreadLocal;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.apache.logging.log4j.ThreadContext;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+/**
+ * @author ding.lid
+ */
+public class Log4j2ContextFilter {
+    static Logger logger = LogManager.getLogger(Log4j2ContextFilter.class);
+
+    // log4j2 context
+    static MtContextThreadLocal<Map<String, String>> mtc = new MtContextThreadLocal<Map<String, String>>() {
+        @Override
+        protected void beforeExecute() {
+            final Map<String, String> log4j2Context = get();
+            for (Map.Entry<String, String> entry : log4j2Context.entrySet()) {
+                ThreadContext.put(entry.getKey(), entry.getValue());
+            }
+        }
+
+        @Override
+        protected void afterExecute() {
+            ThreadContext.clearAll();
+        }
+
+        @Override
+        protected Map<String, String> initialValue() {
+            return new HashMap<String, String>();
+        }
+    };
+
+    public static void main(String[] args) throws Exception {
+        // Init Log Context, set MTC
+        // More KV if needed
+        final String TRACE_ID = "trace-id";
+        final String TRACE_ID_VALUE = "XXX-YYY-ZZZ";
+        ThreadContext.put(TRACE_ID, TRACE_ID_VALUE);
+        mtc.get().put(TRACE_ID, TRACE_ID_VALUE);
+
+        // Log in Main Thread
+        logger.info("Log in main!");
+
+        // Run task in thread pool
+        final ExecutorService executorService = Executors.newFixedThreadPool(1);
+        final Runnable task = new Runnable() {
+            @Override
+            public void run() {
+                // Log in thread pool
+                logger.info("Log in Runnable!");
+            }
+        };
+        final Future<?> submit = executorService.submit(MtContextRunnable.get(task));
+        submit.get();
+
+        executorService.shutdown();
+    }
+}

src/test/resources/log4j2.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="WARN">
+	<Appenders>
+		<Console name="Console" target="SYSTEM_OUT">
+			<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} %X{trace-id} - %msg%n"/>
+		</Console>
+	</Appenders>
+	<Loggers>
+		<Root level="INFO">
+			<AppenderRef ref="Console"/>
+		</Root>
+	</Loggers>
+</Configuration>