BAEL-1767 - Java 9 Platform Logging API (#5071)

* java 9 logger

* slf4j + logback modules added

* new module for slf4j

* logback config

* cleanup

* format

core-java-9/logging.sh

@@ -0,0 +1,15 @@
+# compile logging  module
+# javac --module-path mods -d mods/com.baeldung.logging src/modules/com.baeldung.logging/module-info.java src/modules/com.baeldung.logging/com/baeldung/logging/*.java
+
+# compile logging slf4j module
+javac --module-path mods -d mods/com.baeldung.logging.slf4j src/modules/com.baeldung.logging.slf4j/module-info.java src/modules/com.baeldung.logging.slf4j/com/baeldung/logging/slf4j/*.java
+
+
+# compile logging main app module
+javac --module-path mods -d mods/com.baeldung.logging.app src/modules/com.baeldung.logging.app/module-info.java src/modules/com.baeldung.logging.app/com/baeldung/logging/app/*.java
+
+# run logging main app
+# java --module-path mods -m com.baeldung.logging.app/com.baeldung.logging.app.MainApp
+
+# run looging main app using logback
+java --module-path mods -Dlogback.configurationFile=mods/logback.xml -m com.baeldung.logging.app/com.baeldung.logging.app.MainApp

core-java-9/mods/logback.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
+            <pattern>
+                %d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} -- %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root>
+        <appender-ref ref="STDOUT"/>
+    </root>
+
+</configuration>

core-java-9/src/modules/com.baeldung.logging.app/com/baeldung/logging/app/MainApp.java

@@ -0,0 +1,13 @@
+package com.baeldung.logging.app;
+
+import static java.lang.System.Logger.*;
+
+public class MainApp {
+
+    private static System.Logger LOGGER = System.getLogger("MainApp");
+
+    public static void main(String[] args) {
+        LOGGER.log(Level.ERROR, "error test");
+        LOGGER.log(Level.INFO, "info test");
+    }
+}

core-java-9/src/modules/com.baeldung.logging.app/module-info.java

@@ -0,0 +1,2 @@
+module com.baeldung.logging.app {
+}

core-java-9/src/modules/com.baeldung.logging.slf4j/com/baeldung/logging/slf4j/Slf4jLogger.java

@@ -0,0 +1,99 @@
+package com.baeldung.logging.slf4j;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ResourceBundle;
+
+public class Slf4jLogger implements System.Logger {
+
+    private final String name;
+    private final Logger logger;
+
+    public Slf4jLogger(String name) {
+        this.name = name;
+        logger = LoggerFactory.getLogger(name);
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public boolean isLoggable(Level level) {
+        switch (level) {
+        case OFF:
+            return false;
+        case TRACE:
+            return logger.isTraceEnabled();
+        case DEBUG:
+            return logger.isDebugEnabled();
+        case INFO:
+            return logger.isInfoEnabled();
+        case WARNING:
+            return logger.isWarnEnabled();
+        case ERROR:
+            return logger.isErrorEnabled();
+        case ALL:
+        default:
+            return true;
+        }
+    }
+
+    @Override
+    public void log(Level level, ResourceBundle bundle, String msg, Throwable thrown) {
+        if (!isLoggable(level)) {
+            return;
+        }
+
+        switch (level) {
+        case TRACE:
+            logger.trace(msg, thrown);
+            break;
+        case DEBUG:
+            logger.debug(msg, thrown);
+            break;
+        case INFO:
+            logger.info(msg, thrown);
+            break;
+        case WARNING:
+            logger.warn(msg, thrown);
+            break;
+        case ERROR:
+            logger.error(msg, thrown);
+            break;
+        case ALL:
+        default:
+            logger.info(msg, thrown);
+        }
+    }
+
+    @Override
+    public void log(Level level, ResourceBundle bundle, String format, Object... params) {
+        if (!isLoggable(level)) {
+            return;
+        }
+
+        switch (level) {
+        case TRACE:
+            logger.trace(format, params);
+            break;
+        case DEBUG:
+            logger.debug(format, params);
+            break;
+        case INFO:
+            logger.info(format, params);
+            break;
+        case WARNING:
+            logger.warn(format, params);
+            break;
+        case ERROR:
+            logger.error(format, params);
+            break;
+        case ALL:
+        default:
+            logger.info(format, params);
+        }
+    }
+}

core-java-9/src/modules/com.baeldung.logging.slf4j/com/baeldung/logging/slf4j/Slf4jLoggerFinder.java

@@ -0,0 +1,8 @@
+package com.baeldung.logging.slf4j;
+
+public class Slf4jLoggerFinder extends System.LoggerFinder {
+    @Override
+    public System.Logger getLogger(String name, Module module) {
+        return new Slf4jLogger(name);
+    }
+}

core-java-9/src/modules/com.baeldung.logging.slf4j/module-info.java

@@ -0,0 +1,6 @@
+module com.baeldung.logging.slf4j {
+    requires org.slf4j;
+    provides java.lang.System.LoggerFinder
+      with com.baeldung.logging.slf4j.Slf4jLoggerFinder;
+    exports com.baeldung.logging.slf4j;
+}

core-java-9/src/modules/com.baeldung.logging/com/baeldung/logging/ConsoleLogger.java

@@ -0,0 +1,27 @@
+package com.baeldung.logging;
+
+import java.text.MessageFormat;
+import java.util.ResourceBundle;
+
+public class ConsoleLogger implements System.Logger {
+
+    @Override
+    public String getName() {
+        return "ConsoleLogger";
+    }
+
+    @Override
+    public boolean isLoggable(Level level) {
+        return true;
+    }
+
+    @Override
+    public void log(Level level, ResourceBundle bundle, String msg, Throwable thrown) {
+        System.out.printf("ConsoleLogger [%s]: %s - %s%n", level, msg, thrown);
+    }
+
+    @Override
+    public void log(Level level, ResourceBundle bundle, String format, Object... params) {
+        System.out.printf("ConsoleLogger [%s]: %s%n", level, MessageFormat.format(format, params));
+    }
+}

core-java-9/src/modules/com.baeldung.logging/com/baeldung/logging/CustomLoggerFinder.java

@@ -0,0 +1,9 @@
+package com.baeldung.logging;
+
+public class CustomLoggerFinder extends System.LoggerFinder {
+
+    @Override
+    public System.Logger getLogger(String name, Module module) {
+        return new ConsoleLogger();
+    }
+}

core-java-9/src/modules/com.baeldung.logging/module-info.java

@@ -0,0 +1,5 @@
+module com.baeldung.logging {
+    provides java.lang.System.LoggerFinder
+      with com.baeldung.logging.CustomLoggerFinder;
+    exports com.baeldung.logging;
+}