WW-4492 Add support for Log4J2 as a struts and xwork logging backend

pom.xml

@@ -857,12 +857,18 @@
             <dependency>
                 <groupId>org.slf4j</groupId>
                 <artifactId>slf4j-api</artifactId>
-                <version>1.7.2</version>
+                <version>1.7.12</version>
             </dependency>
             <dependency>
                 <groupId>org.slf4j</groupId>
                 <artifactId>slf4j-simple</artifactId>
-                <version>1.7.2</version>
+                <version>1.7.12</version>
+            </dependency>
+
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-api</artifactId>
+                <version>2.2</version>
             </dependency>
 
             <dependency>

xwork-core/pom.xml

@@ -219,6 +219,13 @@
             <artifactId>slf4j-simple</artifactId>
             <optional>true</optional>
         </dependency>
+
+        <!-- Log4J2 support -->
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-api</artifactId>
+            <optional>true</optional>
+        </dependency>
     </dependencies>
 
 </project>

xwork-core/src/main/java/com/opensymphony/xwork2/util/logging/log4j2/Log4j2Logger.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright 2002-2006,2009 The Apache Software Foundation.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.opensymphony.xwork2.util.logging.log4j2;
+
+import com.opensymphony.xwork2.util.logging.Logger;
+import com.opensymphony.xwork2.util.logging.LoggerUtils;
+
+/**
+ * Simple logger that delegates to log4j2 logging
+ */
+public class Log4j2Logger implements Logger {
+
+    private org.apache.logging.log4j.Logger log;
+
+    public Log4j2Logger(org.apache.logging.log4j.Logger log) {
+        this.log = log;
+    }
+
+    public void error(String msg, String... args) {
+        log.error(LoggerUtils.format(msg, args));
+    }
+
+    public void error(String msg, Object... args) {
+        log.error(LoggerUtils.format(msg, args));
+    }
+
+    public void error(String msg, Throwable ex, String... args) {
+        log.error(LoggerUtils.format(msg, args), ex);
+    }
+
+    public void info(String msg, String... args) {
+        log.info(LoggerUtils.format(msg, args));
+    }
+
+    public void info(String msg, Throwable ex, String... args) {
+        log.info(LoggerUtils.format(msg, args), ex);
+    }
+
+    public boolean isInfoEnabled() {
+        return log.isInfoEnabled();
+    }
+
+    public void warn(String msg, String... args) {
+        log.warn(LoggerUtils.format(msg, args));
+    }
+
+    public void warn(String msg, Object... args) {
+        log.warn(LoggerUtils.format(msg, args));
+    }
+
+    public void warn(String msg, Throwable ex, String... args) {
+        log.warn(LoggerUtils.format(msg, args), ex);
+    }
+
+    public boolean isDebugEnabled() {
+        return log.isDebugEnabled();
+    }
+
+    public void debug(String msg, String... args) {
+        log.debug(LoggerUtils.format(msg, args));
+    }
+
+    public void debug(String msg, Object... args) {
+        log.debug(LoggerUtils.format(msg, args));
+    }
+
+    public void debug(String msg, Throwable ex, String... args) {
+        log.debug(LoggerUtils.format(msg, args), ex);
+    }
+
+    public boolean isTraceEnabled() {
+        return log.isTraceEnabled();
+    }
+
+    public void trace(String msg, String... args) {
+        log.trace(LoggerUtils.format(msg, args));
+    }
+
+    public void trace(String msg, Object... args) {
+        log.trace(LoggerUtils.format(msg, args));
+    }
+
+    public void trace(String msg, Throwable ex, String... args) {
+        log.trace(LoggerUtils.format(msg, args), ex);
+    }
+
+
+    public void fatal(String msg, String... args) {
+        log.fatal(LoggerUtils.format(msg, args));
+    }
+
+    public void fatal(String msg, Throwable ex, String... args) {
+        log.fatal(LoggerUtils.format(msg, args), ex);
+    }
+
+    public boolean isErrorEnabled() {
+        return log.isErrorEnabled();
+    }
+
+    public boolean isFatalEnabled() {
+        return log.isFatalEnabled();
+    }
+
+    public boolean isWarnEnabled() {
+        return log.isWarnEnabled();
+    }
+
+}

xwork-core/src/main/java/com/opensymphony/xwork2/util/logging/log4j2/Log4j2LoggerFactory.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2002-2006,2009 The Apache Software Foundation.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.opensymphony.xwork2.util.logging.log4j2;
+
+import com.opensymphony.xwork2.util.logging.Logger;
+import com.opensymphony.xwork2.util.logging.LoggerFactory;
+
+/**
+ * Creates log4j2-logging-backed loggers
+ *
+ * You can use the same to explicit tell the framework which implementation to use and don't depend on class discovery:
+ * <pre>
+ *   -Dxwork.loggerFactory=com.opensymphony.xwork2.util.logging.log4j2.Log4j2LoggerFactory
+ * </pre>
+ */
+public class Log4j2LoggerFactory extends LoggerFactory {
+
+    @Override
+    protected Logger getLoggerImpl(Class<?> cls) {
+        return new Log4j2Logger(org.apache.logging.log4j.LogManager.getLogger(cls));
+    }
+
+    @Override
+    protected Logger getLoggerImpl(String name) {
+        return new Log4j2Logger(org.apache.logging.log4j.LogManager.getLogger(name));
+    }
+
+}

xwork-core/src/main/java/com/opensymphony/xwork2/util/logging/slf4j/Slf4jLoggerFactory.java

@@ -20,6 +20,11 @@
 
 /**
  * Creates slf4j-logging-backed loggers
+ *
+ * You can use the same to explicit tell the framework which implementation to use and don't depend on class discovery:
+ * <pre>
+ *   -Dxwork.loggerFactory=com.opensymphony.xwork2.util.logging.slf4j.Slf4jLoggerFactory
+ * </pre>
  */
 public class Slf4jLoggerFactory extends LoggerFactory {