Migrate to SLF4J for logging

As noted in diffplug#1116, it'd be ideal if we moved to SLF4J as our logging
interface.

We can do this pretty easily, making sure we remove our `package-list`
reference, as well as making sure the SLF4J API is only used for
compilation.

We also need to map the error logging levels that most closely mirror
what `java.util.logging` uses.

Closes diffplug#1116.

gradle/javadoc/java8/package-list

@@ -55,7 +55,6 @@ java.util.concurrent.atomic
 java.util.concurrent.locks
 java.util.function
 java.util.jar
-java.util.logging
 java.util.prefs
 java.util.regex
 java.util.spi

lib/build.gradle

@@ -21,6 +21,7 @@ for (glue in NEEDS_GLUE) {
 }
 
 dependencies {
+	compileOnly 'org.slf4j:slf4j-api:1.7.35'
 	// zero runtime reqs is a hard requirements for spotless-lib
 	// if you need a dep, put it in lib-extra
 	testImplementation "org.junit.jupiter:junit-jupiter:$VER_JUNIT"
@@ -29,6 +30,7 @@ dependencies {
 
 	// used for pom sorting
 	sortPomCompileOnly 'com.github.ekryd.sortpom:sortpom-sorter:3.0.0'
+	sortPomCompileOnly 'org.slf4j:slf4j-api:1.7.35'
 
 	palantirJavaFormatCompileOnly 'com.palantir.javaformat:palantir-java-format:1.1.0'
 

lib/src/ktlint/java/com/diffplug/spotless/glue/ktlint/KtlintFormatterFunc.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 DiffPlug
+ * Copyright 2021-2022 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

lib/src/main/java/com/diffplug/spotless/FormatExceptionPolicyLegacy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 DiffPlug
+ * Copyright 2016-2022 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,13 +15,13 @@
  */
 package com.diffplug.spotless;
 
-import java.util.logging.Level;
-import java.util.logging.Logger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 class FormatExceptionPolicyLegacy extends NoLambda.EqualityBasedOnSerialization implements FormatExceptionPolicy {
 	private static final long serialVersionUID = 1L;
 
-	private static final Logger logger = Logger.getLogger(Formatter.class.getName());
+	private static final Logger logger = LoggerFactory.getLogger(Formatter.class.getName());
 
 	@Override
 	public void handleError(Throwable e, FormatterStep step, String relativePath) {
@@ -34,10 +34,10 @@ public void handleError(Throwable e, FormatterStep step, String relativePath) {
 	}
 
 	static void error(Throwable e, FormatterStep step, String relativePath) {
-		logger.log(Level.SEVERE, "Step '" + step.getName() + "' found problem in '" + relativePath + "':\n" + e.getMessage(), e);
+		logger.error("Step '" + step.getName() + "' found problem in '" + relativePath + "':\n" + e.getMessage(), e);
 	}
 
 	static void warning(Throwable e, FormatterStep step, String relativePath) {
-		logger.log(Level.WARNING, "Unable to apply step '" + step.getName() + "' to '" + relativePath + "'", e);
+		logger.warn("Unable to apply step '" + step.getName() + "' to '" + relativePath + "'", e);
 	}
 }

lib/src/main/java/com/diffplug/spotless/markdown/FreshMarkStep.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 DiffPlug
+ * Copyright 2016-2022 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,9 @@
 import java.util.Objects;
 import java.util.TreeMap;
 import java.util.function.Consumer;
-import java.util.logging.Logger;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import com.diffplug.spotless.FormatterFunc;
 import com.diffplug.spotless.FormatterStep;
@@ -78,8 +80,8 @@ private static class State implements Serializable {
 		}
 
 		FormatterFunc createFormat() throws Exception {
-			Logger logger = Logger.getLogger(FreshMarkStep.class.getName());
-			Consumer<String> loggingStream = logger::warning;
+			Logger logger = LoggerFactory.getLogger(FreshMarkStep.class.getName());
+			Consumer<String> loggingStream = logger::warn;
 
 			ClassLoader classLoader = jarState.getClassLoader();
 

lib/src/main/java/com/diffplug/spotless/npm/NpmFormatterStepStateBase.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 DiffPlug
+ * Copyright 2016-2022 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,7 +27,9 @@
 import java.util.Map.Entry;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
-import java.util.logging.Logger;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import com.diffplug.spotless.FileSignature;
 import com.diffplug.spotless.FormatterFunc;
@@ -36,7 +38,7 @@
 
 abstract class NpmFormatterStepStateBase implements Serializable {
 
-	private static final Logger logger = Logger.getLogger(NpmFormatterStepStateBase.class.getName());
+	private static final Logger logger = LoggerFactory.getLogger(NpmFormatterStepStateBase.class.getName());
 
 	private static final long serialVersionUID = 1460749955865959948L;
 
@@ -166,13 +168,13 @@ public String getBaseUrl() {
 		@Override
 		public void close() throws Exception {
 			try {
-				logger.fine("Closing npm server in directory <" + serverPortFile.getParent() + "> and port <" + serverPort + ">");
+				logger.trace("Closing npm server in directory <" + serverPortFile.getParent() + "> and port <" + serverPort + ">");
 				if (server.isAlive()) {
 					boolean ended = server.waitFor(5, TimeUnit.SECONDS);
 					if (!ended) {
 						logger.info("Force-Closing npm server in directory <" + serverPortFile.getParent() + "> and port <" + serverPort + ">");
 						server.destroyForcibly().waitFor();
-						logger.fine("Force-Closing npm server in directory <" + serverPortFile.getParent() + "> and port <" + serverPort + "> -- Finished");
+						logger.trace("Force-Closing npm server in directory <" + serverPortFile.getParent() + "> and port <" + serverPort + "> -- Finished");
 					}
 				}
 			} finally {

lib/src/main/java/com/diffplug/spotless/npm/PrettierFormatterStep.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 DiffPlug
+ * Copyright 2016-2022 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,11 +23,12 @@
 import java.util.Collections;
 import java.util.Map;
 import java.util.TreeMap;
-import java.util.logging.Level;
-import java.util.logging.Logger;
 
 import javax.annotation.Nonnull;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import com.diffplug.spotless.FormatterFunc;
 import com.diffplug.spotless.FormatterFunc.Closeable;
 import com.diffplug.spotless.FormatterStep;
@@ -36,7 +37,7 @@
 
 public class PrettierFormatterStep {
 
-	private static final Logger logger = Logger.getLogger(PrettierFormatterStep.class.getName());
+	private static final Logger logger = LoggerFactory.getLogger(PrettierFormatterStep.class.getName());
 
 	public static final String NAME = "prettier-format";
 
@@ -95,7 +96,7 @@ private void endServer(PrettierRestService restService, ServerProcessInfo restSe
 			try {
 				restService.shutdown();
 			} catch (Throwable t) {
-				logger.log(Level.INFO, "Failed to request shutdown of rest service via api. Trying via process.", t);
+				logger.info("Failed to request shutdown of rest service via api. Trying via process.", t);
 			}
 			restServer.close();
 		}

lib/src/main/java/com/diffplug/spotless/npm/TsFmtFormatterStep.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 DiffPlug
+ * Copyright 2016-2022 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,12 +21,13 @@
 import java.io.IOException;
 import java.io.Serializable;
 import java.util.*;
-import java.util.logging.Level;
-import java.util.logging.Logger;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import com.diffplug.spotless.FormatterFunc;
 import com.diffplug.spotless.FormatterFunc.Closeable;
 import com.diffplug.spotless.FormatterStep;
@@ -35,7 +36,7 @@
 
 public class TsFmtFormatterStep {
 
-	private static final Logger logger = Logger.getLogger(TsFmtFormatterStep.class.getName());
+	private static final Logger logger = LoggerFactory.getLogger(TsFmtFormatterStep.class.getName());
 
 	public static final String NAME = "tsfmt-format";
 
@@ -115,7 +116,7 @@ private void endServer(TsFmtRestService restService, ServerProcessInfo restServe
 			try {
 				restService.shutdown();
 			} catch (Throwable t) {
-				logger.log(Level.INFO, "Failed to request shutdown of rest service via api. Trying via process.", t);
+				logger.info("Failed to request shutdown of rest service via api. Trying via process.", t);
 			}
 			restServer.close();
 		}

lib/src/sortPom/java/com/diffplug/spotless/glue/pom/SortPomFormatterFunc.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 DiffPlug
+ * Copyright 2021-2022 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,9 +18,10 @@
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
-import java.util.logging.Logger;
 
 import org.apache.commons.io.IOUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import com.diffplug.spotless.FormatterFunc;
 import com.diffplug.spotless.pom.SortPomCfg;
@@ -30,7 +31,7 @@
 import sortpom.parameter.PluginParameters;
 
 public class SortPomFormatterFunc implements FormatterFunc {
-	private static final Logger logger = Logger.getLogger(SortPomFormatterFunc.class.getName());
+	private static final Logger logger = LoggerFactory.getLogger(SortPomFormatterFunc.class.getName());
 	private final SortPomCfg cfg;
 
 	public SortPomFormatterFunc(SortPomCfg cfg) {
@@ -61,7 +62,7 @@ public String apply(String input) throws Exception {
 	private static class MySortPomLogger implements SortPomLogger {
 		@Override
 		public void warn(String content) {
-			logger.warning(content);
+			logger.warn(content);
 		}
 
 		@Override
@@ -71,7 +72,7 @@ public void info(String content) {
 
 		@Override
 		public void error(String content) {
-			logger.severe(content);
+			logger.error(content);
 		}
 	}
 }

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/GradleProvisioner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 DiffPlug
+ * Copyright 2016-2022 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,8 +20,6 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
-import java.util.logging.Level;
-import java.util.logging.Logger;
 
 import org.gradle.api.GradleException;
 import org.gradle.api.Project;
@@ -30,6 +28,8 @@
 import org.gradle.api.artifacts.dsl.DependencyHandler;
 import org.gradle.api.attributes.Bundling;
 import org.gradle.api.initialization.dsl.ScriptHandler;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import com.diffplug.common.base.Unhandled;
 import com.diffplug.common.collect.ImmutableList;
@@ -127,8 +127,7 @@ private static Provisioner forConfigurationContainer(Project project, Configurat
 				if (!projName.isEmpty()) {
 					projName = projName + "/";
 				}
-				logger.log(
-						Level.SEVERE,
+				logger.error(
 						"You need to add a repository containing the '" + mavenCoords + "' artifact in '" + projName + "build.gradle'.\n" +
 								"E.g.: 'repositories { mavenCentral() }'",
 						e);
@@ -137,7 +136,7 @@ private static Provisioner forConfigurationContainer(Project project, Configurat
 		};
 	}
 
-	private static final Logger logger = Logger.getLogger(GradleProvisioner.class.getName());
+	private static final Logger logger = LoggerFactory.getLogger(GradleProvisioner.class.getName());
 
 	/** Models a request to the provisioner. */
 	private static class Request {