Merge pull request #8125 from eugenp/revert-8119-BAEL-3275-2

Revert "BAEL-3275: Using blocking queue for pub-sub"

logging-modules/log4j2/src/main/java/com/baeldung/logging/log4j2/Log4j2ComparisonSysout.java

@@ -0,0 +1,18 @@
+package com.baeldung.logging.log4j2;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.PrintStream;
+
+public class Log4j2ComparisonSysout {
+
+    public static void main(String[] args) throws FileNotFoundException {
+        PrintStream outStream = new PrintStream(new File("outFile.txt"));
+        System.setOut(outStream);
+        System.out.println("This is a baeldung article");
+        
+        PrintStream errStream = new PrintStream(new File("errFile.txt"));
+        System.setErr(errStream);
+        System.err.println("This is a baeldung article error");
+    }
+}

logging-modules/log4j2/src/main/java/com/baeldung/logging/log4j2/Log4j2Example.java

@@ -0,0 +1,19 @@
+package com.baeldung.logging.log4j2;
+
+import org.apache.logging.log4j.Logger;
+import org.apache.logging.log4j.LogManager;
+
+public class Log4j2Example {
+
+    private static final Logger logger = LogManager.getLogger(Log4j2Example.class);
+
+    public static void main(String[] args) {
+        logger.debug("Debug log message");
+        logger.info("Info log message");
+        logger.error("Error log message");
+        logger.warn("Warn log message");
+        logger.fatal("Fatal log message");
+        logger.trace("Trace log message");
+    }
+
+}

logging-modules/log4j2/src/main/java/com/baeldung/logging/log4j2/appender/MapAppender.java

@@ -0,0 +1,54 @@
+/**
+ * 
+ */
+package com.baeldung.logging.log4j2.appender;
+
+import java.time.Instant;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.Appender;
+import org.apache.logging.log4j.core.Core;
+import org.apache.logging.log4j.core.Filter;
+import org.apache.logging.log4j.core.LogEvent;
+import org.apache.logging.log4j.core.appender.AbstractAppender;
+import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
+import org.apache.logging.log4j.core.config.plugins.PluginElement;
+import org.apache.logging.log4j.core.config.plugins.PluginFactory;
+
+@Plugin(name = "MapAppender", category = Core.CATEGORY_NAME, elementType = Appender.ELEMENT_TYPE)
+public class MapAppender extends AbstractAppender {
+
+    private ConcurrentMap<String, LogEvent> eventMap = new ConcurrentHashMap<>();
+
+    protected MapAppender(String name, Filter filter) {
+        super(name, filter, null);
+    }
+
+    @PluginFactory
+    public static MapAppender createAppender(@PluginAttribute("name") String name, @PluginElement("Filter") final Filter filter) {
+        return new MapAppender(name, filter);
+    }
+
+    @Override
+    public void append(LogEvent event) {
+        if (event.getLevel()
+            .isLessSpecificThan(Level.WARN)) {
+            error("Unable to log less than WARN level.");
+            return;
+        }
+        eventMap.put(Instant.now()
+            .toString(), event);
+    }
+
+    public ConcurrentMap<String, LogEvent> getEventMap() {
+        return eventMap;
+    }
+
+    public void setEventMap(ConcurrentMap<String, LogEvent> eventMap) {
+        this.eventMap = eventMap;
+    }
+
+}