BAEL-3321 Flogger fluent logging (eugenp#7824)

* Added Flogger maven dependency

* Implemented Flogger logging examples

* Finished implementing Flogger logging examples

* Changed Flogger Test to Integration tests

Author: Alfred-Samanga

logging-modules/flogger/pom.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>logging-modules</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>flogger</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.google.flogger</groupId>
+            <artifactId>flogger</artifactId>
+            <version>0.4</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.flogger</groupId>
+            <artifactId>flogger-system-backend</artifactId>
+            <version>0.4</version>
+            <scope>runtime</scope>
+        </dependency>
+    </dependencies>
+</project>

logging-modules/flogger/src/main/java/com/baeldung/flogger/FloggerExamples.java

@@ -0,0 +1,17 @@
+package com.baeldung.flogger;
+
+import com.google.common.flogger.FluentLogger;
+import com.google.common.flogger.LoggerConfig;
+
+import java.util.logging.Level;
+
+public class FloggerExamples {
+
+    private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+    public static void main(String[] args) {
+        LoggerConfig.of(logger).setLevel(Level.FINE);
+        Exception exception = new Exception("This is a test exception.");
+        logger.atInfo().withCause(exception).log("Log message with: %s", "Alfred");
+    }
+}

logging-modules/flogger/src/test/java/com/baeldung/flogger/FloggerIntegrationTest.java

@@ -0,0 +1,73 @@
+package com.baeldung.flogger;
+
+import com.google.common.flogger.FluentLogger;
+import com.google.common.flogger.LoggerConfig;
+import com.google.common.flogger.StackSize;
+import org.junit.Test;
+
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.stream.IntStream;
+
+import static com.google.common.flogger.LazyArgs.lazy;
+
+public class FloggerIntegrationTest {
+    private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+    @Test
+    public void givenAnInterval_shouldLogAfterEveryInterval() {
+        IntStream.range(0, 100).forEach(value -> {
+            logger.atInfo().every(40).log("This log shows [every 40 iterations] => %d", value);
+        });
+    }
+
+    @Test
+    public void givenATimeInterval_shouldLogAfterEveryTimeInterval() {
+        IntStream.range(0, 1_000_0000).forEach(value -> {
+            logger.atInfo().atMostEvery(10, TimeUnit.SECONDS).log("This log shows [every 10 seconds] => %d", value);
+        });
+    }
+
+    @Test
+    public void givenASimpleOperation_shouldLogTheResult() {
+        int result = 45 / 3;
+        logger.atInfo().log("The result is %d", result);
+    }
+
+    @Test
+    public void givenCodeThatThrowsAndException_shouldLogTheException() {
+        try {
+            int result = 45 / 0;
+        } catch (RuntimeException re) {
+            logger.atInfo().withStackTrace(StackSize.FULL).withCause(re).log("Message");
+        }
+    }
+
+    @Test
+    public void givenALoggingConfiguration_shouldLogAtTheConfiguredLevel() {
+        LoggerConfig.of(logger).setLevel(Level.FINE);
+        logger.atInfo().log("Info Message");
+        logger.atWarning().log("Warning Message");
+        logger.atSevere().log("Severe Message");
+        logger.atFinest().log("Finest Message");
+        logger.atFine().log("Fine Message");
+        logger.atFiner().log("Finer Message");
+        logger.atConfig().log("Config Message");
+    }
+
+    @Test
+    public void givenALongRunningMethodForStats_shouldCallTheMethodLazily() {
+        //Wrong way of doing it
+        logger.atFine().log("stats=%s", collectSummaries());
+
+        // Almost no work done at the log site and structure is preserved.
+        logger.atFine().log("stats=%s", lazy(() -> collectSummaries()));
+    }
+
+    public static String collectSummaries() {
+        //compute summaries in a long-running process
+        int items = 110;
+        int s = 30;
+        return String.format("%d seconds elapsed so far. %d items pending processing", s, items);
+    }
+}

logging-modules/pom.xml

@@ -18,6 +18,7 @@
         <module>log4j2</module>
         <module>logback</module>
         <module>log-mdc</module>
+        <module>flogger</module>
     </modules>
 
 </project>