refactor: use slf4j API instead of log4j-api

pom.xml

@@ -68,18 +68,13 @@
       <artifactId>jsap</artifactId>
       <version>2.1</version>
     </dependency>
+    <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
     <dependency>
-        <!-- doc: https://logging.apache.org/log4j/2.0/faq.html -->
-        <groupId>org.apache.logging.log4j</groupId>
-      <artifactId>log4j-api</artifactId>
-      <version>2.14.0</version>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-api</artifactId>
+      <version>1.7.30</version>
     </dependency>
-    <dependency>
-        <groupId>org.apache.logging.log4j</groupId>
-        <artifactId>log4j-to-slf4j</artifactId>
-        <version>2.14.0</version>
-    </dependency>
-    <dependency>
+      <dependency>
       <groupId>commons-io</groupId>
       <artifactId>commons-io</artifactId>
       <version>2.8.0</version>

spoon-pom/pom.xml

@@ -34,7 +34,7 @@
     </repositories>
 
     <dependencies>
-        
+
         <!-- we all depend on Junit with scope=test -->
         <dependency>
             <groupId>org.junit.vintage</groupId>
@@ -102,24 +102,6 @@
 
     <build>
         <defaultGoal>clean install</defaultGoal>
-
-        <resources>
-            <resource>
-                <directory>src/main/resources</directory>
-                <filtering>true</filtering>
-                <excludes>
-                    <exclude>log4j.properties</exclude>
-                </excludes>
-            </resource>
-            <resource>
-                <directory>src/main/resources</directory>
-                <filtering>false</filtering>
-                <includes>
-                    <include>log4j.properties</include>
-                </includes>
-            </resource>
-        </resources>
-
         <plugins>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>

src/main/java/spoon/Launcher.java

@@ -17,9 +17,9 @@
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.io.filefilter.IOFileFilter;
 import org.apache.commons.lang3.StringUtils;
-import org.apache.logging.log4j.Level;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.event.Level;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import spoon.SpoonModelBuilder.InputType;
 import spoon.compiler.Environment;
 import spoon.compiler.SpoonResource;
@@ -46,6 +46,7 @@
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.lang.invoke.MethodHandles;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -540,7 +541,7 @@ protected void processArguments() {
 
 	protected void reportClassPathMode() {
 		String cpmode = jsapActualArgs.getString("cpmode").toUpperCase();
-		Launcher.LOGGER.info("Running in " + cpmode + " mode (doc: http://spoon.gforge.inria.fr/launcher.html).");
+		factory.getEnvironment().report(null, Level.INFO, "Running in " + cpmode + " mode (doc: http://spoon.gforge.inria.fr/launcher.html).");
 	}
 
 	/**
@@ -591,7 +592,7 @@ protected JSAPResult parseArgs() {
 	/**
 	 * A default logger to be used by Spoon.
 	 */
-	public static final Logger LOGGER = LogManager.getLogger();
+	public static final Logger LOGGER = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
 	/**
 	 * Creates a new Spoon Java compiler in order to process and compile Java

src/main/java/spoon/MavenLauncher.java

@@ -7,11 +7,12 @@
  */
 package spoon;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import spoon.support.compiler.SpoonPom;
 
 import java.io.File;
+import java.lang.invoke.MethodHandles;
 import java.util.List;
 import java.util.regex.Pattern;
 
@@ -23,7 +24,7 @@ public class MavenLauncher extends Launcher {
 	private SOURCE_TYPE sourceType;
 	private SpoonPom model;
 	private boolean forceRefresh = false;
-	private static final Logger LOGGER  = LogManager.getLogger();
+	private static final Logger LOGGER  = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
 	/**
 	 * @return SpoonPom corresponding to the pom file used by the launcher

src/main/java/spoon/compiler/Environment.java

@@ -7,7 +7,7 @@
  */
 package spoon.compiler;
 
-import org.apache.logging.log4j.Level;
+import org.slf4j.event.Level;
 import spoon.OutputType;
 import spoon.compiler.builder.EncodingProvider;
 import spoon.processing.FileGenerator;

src/main/java/spoon/processing/AbstractProcessor.java

@@ -7,7 +7,7 @@
  */
 package spoon.processing;
 
-import org.apache.logging.log4j.Level;
+import org.slf4j.event.Level;
 import spoon.Launcher;
 import spoon.compiler.Environment;
 import spoon.reflect.declaration.CtElement;

src/main/java/spoon/reflect/visitor/DefaultJavaPrettyPrinter.java

@@ -7,8 +7,8 @@
  */
 package spoon.reflect.visitor;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import spoon.SpoonException;
 import spoon.compiler.Environment;
 import spoon.experimental.CtUnresolvedImport;
@@ -120,6 +120,7 @@
 import spoon.support.util.ModelList;
 
 import java.lang.annotation.Annotation;
+import java.lang.invoke.MethodHandles;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -244,7 +245,7 @@ public DefaultJavaPrettyPrinter setLineSeparator(String lineSeparator) {
 	}
 
 
-	protected static final Logger LOGGER = LogManager.getLogger();
+	protected static final Logger LOGGER = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 	public static final String ERROR_MESSAGE_TO_STRING = "Error in printing the node. One parent isn't initialized!";
 	/**
 	 * Prints an element. This method shall be called by the toString() method of an element.

src/main/java/spoon/reflect/visitor/ModelConsistencyChecker.java

@@ -7,7 +7,7 @@
  */
 package spoon.reflect.visitor;
 
-import org.apache.logging.log4j.Level;
+import org.slf4j.event.Level;
 import spoon.compiler.Environment;
 import spoon.reflect.declaration.CtElement;
 import spoon.reflect.declaration.CtNamedElement;

src/main/java/spoon/support/RuntimeProcessingManager.java

@@ -7,7 +7,7 @@
  */
 package spoon.support;
 
-import org.apache.logging.log4j.Level;
+import org.slf4j.event.Level;
 import spoon.processing.ProcessInterruption;
 import spoon.processing.ProcessingManager;
 import spoon.processing.Processor;

src/main/java/spoon/support/StandardEnvironment.java

@@ -8,8 +8,8 @@
 package spoon.support;
 
 
-import org.apache.logging.log4j.Level;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.event.Level;
+import org.slf4j.Logger;
 import spoon.Launcher;
 import spoon.OutputType;
 import spoon.SpoonException;
@@ -98,7 +98,7 @@ public void setPrettyPrintingMode(PRETTY_PRINTING_MODE prettyPrintingMode) {
 
 	private transient  Logger logger = Launcher.LOGGER;
 
-	private Level level = Level.OFF;
+	private Level level = Level.ERROR;
 
 	private boolean shouldCompile = false;
 
@@ -193,7 +193,13 @@ private Level toLevel(String level) {
 		if (level == null || level.isEmpty()) {
 			throw new SpoonException("Wrong level given at Spoon.");
 		}
-		return Level.toLevel(level, Level.ALL);
+		Level levelEnum;
+		try {
+			levelEnum = Level.valueOf(level);
+		} catch (IllegalArgumentException e) {
+			return Level.TRACE;
+		}
+		return levelEnum;
 	}
 
 	@Override
@@ -273,8 +279,18 @@ public void report(Processor<?> processor, Level level, String message) {
 	}
 
 	private void print(String message, Level messageLevel) {
-		if (messageLevel.isMoreSpecificThan(this.level)) {
-			logger.log(messageLevel, message);
+		if (messageLevel.toInt() >= this.level.toInt()) {
+			switch (messageLevel) {
+				case ERROR: logger.error(message);
+					break;
+				case WARN: logger.warn(message);
+					break;
+				case INFO: logger.info(message);
+					break;
+				case DEBUG: logger.debug(message);
+					break;
+				case TRACE: logger.trace(message);
+			}
 		}
 	}
 

src/main/java/spoon/support/compiler/SpoonPom.java

@@ -7,7 +7,7 @@
  */
 package spoon.support.compiler;
 
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 import org.apache.maven.model.Build;
 import org.apache.maven.model.BuildBase;
 import org.apache.maven.model.Model;

src/main/java/spoon/support/compiler/jdt/JDTBasedSpoonCompiler.java

@@ -8,7 +8,7 @@
 package spoon.support.compiler.jdt;
 
 import org.apache.commons.io.IOUtils;
-import org.apache.logging.log4j.Level;
+import org.slf4j.event.Level;
 import org.eclipse.jdt.core.compiler.CategorizedProblem;
 import org.eclipse.jdt.core.compiler.IProblem;
 import org.eclipse.jdt.internal.compiler.ASTVisitor;

src/main/java/spoon/support/compiler/jdt/JDTCommentBuilder.java

@@ -7,8 +7,8 @@
  */
 package spoon.support.compiler.jdt;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.eclipse.jdt.internal.compiler.ast.CompilationUnitDeclaration;
 import org.eclipse.jdt.internal.compiler.env.ICompilationUnit;
 import spoon.SpoonException;
@@ -61,6 +61,7 @@
 import java.io.Reader;
 import java.io.StringReader;
 import java.lang.annotation.Annotation;
+import java.lang.invoke.MethodHandles;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
@@ -71,7 +72,7 @@
  */
 public class JDTCommentBuilder {
 
-	private static final Logger LOGGER = LogManager.getLogger();
+	private static final Logger LOGGER = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
 	private final CompilationUnitDeclaration declarationUnit;
 	private CompilationUnit spoonUnit;

src/main/java/spoon/support/compiler/jdt/JDTTreeBuilder.java

@@ -7,8 +7,7 @@
  */
 package spoon.support.compiler.jdt;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 import org.eclipse.jdt.core.compiler.CharOperation;
 import org.eclipse.jdt.internal.compiler.ASTVisitor;
 import org.eclipse.jdt.internal.compiler.ast.AND_AND_Expression;
@@ -113,6 +112,7 @@
 import org.eclipse.jdt.internal.compiler.lookup.Scope;
 import org.eclipse.jdt.internal.compiler.lookup.TypeBinding;
 import org.eclipse.jdt.internal.compiler.lookup.VariableBinding;
+import org.slf4j.LoggerFactory;
 import spoon.SpoonException;
 import spoon.reflect.code.BinaryOperatorKind;
 import spoon.reflect.code.CtArrayAccess;
@@ -159,6 +159,8 @@
 import spoon.support.compiler.jdt.ContextBuilder.CastInfo;
 import spoon.support.reflect.CtExtendedModifier;
 
+import java.lang.invoke.MethodHandles;
+
 import static spoon.support.compiler.jdt.JDTTreeBuilderQuery.getBinaryOperatorKind;
 import static spoon.support.compiler.jdt.JDTTreeBuilderQuery.getModifiers;
 import static spoon.support.compiler.jdt.JDTTreeBuilderQuery.getUnaryOperator;
@@ -187,7 +189,7 @@ public static Logger getLogger() {
 		return LOGGER;
 	}
 
-	private static final Logger LOGGER = LogManager.getLogger();
+	private static final Logger LOGGER = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
 	public PositionBuilder getPositionBuilder() {
 		return position;

src/main/java/spoon/support/reflect/declaration/CtElementImpl.java

@@ -7,8 +7,8 @@
  */
 package spoon.support.reflect.declaration;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import spoon.reflect.ModelElementContainerDefaultCapacities;
 import spoon.reflect.annotations.MetamodelPropertyField;
 import spoon.reflect.code.CtBlock;
@@ -57,6 +57,7 @@
 
 import java.io.Serializable;
 import java.lang.annotation.Annotation;
+import java.lang.invoke.MethodHandles;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -74,7 +75,7 @@
  */
 public abstract class CtElementImpl implements CtElement, Serializable {
 	private static final long serialVersionUID = 1L;
-	protected static final Logger LOGGER = LogManager.getLogger();
+	protected static final Logger LOGGER = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 	public static final String ERROR_MESSAGE_TO_STRING = "Error in printing the node. One parent isn't initialized!";
 	private static final Factory DEFAULT_FACTORY = new FactoryImpl(new DefaultCoreFactory(), new StandardEnvironment());