Add "quiet" parameter

Closes #103

README.md

@@ -92,7 +92,7 @@ Retrolambda takes Java 8 classes and backports lambda expressions and
 some other language features to work on Java 7, 6 or 5.
 Web site: https://github.com/orfjackal/retrolambda
 
-Copyright (c) 2013-2016  Esko Luontola and other Retrolambda contributors
+Copyright (c) 2013-2017  Esko Luontola and other Retrolambda contributors
 This software is released under the Apache License 2.0.
 The license text is at http://www.apache.org/licenses/LICENSE-2.0
 
@@ -136,6 +136,10 @@ Configurable system properties:
       Alternative to retrolambda.includedFiles for avoiding the command line
       length limit. The file must list one file per line with UTF-8 encoding.
 
+  retrolambda.quiet
+      Reduces the amount of logging.
+      Disabled by default. Enable by setting to "true"
+
 If the Java agent is used, then Retrolambda will use it to capture the
 lambda classes generated by Java. Otherwise Retrolambda will hook into
 Java's internal lambda dumping API, which is more susceptible to suddenly
@@ -226,6 +230,8 @@ Version History
 
 ### Upcoming
 
+- Added an option to reduce the amount of logging
+  ([Issue #103](https://github.com/orfjackal/retrolambda/issues/103))
 - Removes `java/lang/invoke/LambdaForm$Hidden` annotations from the generated 
   lambda classes to avoid issues with ProGuard 
   ([Pull request #118](https://github.com/orfjackal/retrolambda/pull/118))

retrolambda-maven-plugin/src/main/java/net/orfjackal/retrolambda/maven/ProcessClassesMojo.java

@@ -1,4 +1,4 @@
-// Copyright © 2013-2015 Esko Luontola <www.orfjackal.net>
+// Copyright © 2013-2017 Esko Luontola and other Retrolambda contributors
 // This software is released under the Apache License 2.0.
 // The license text is at http://www.apache.org/licenses/LICENSE-2.0
 
@@ -78,6 +78,14 @@ abstract class ProcessClassesMojo extends AbstractMojo {
     @Parameter(defaultValue = "false", property = "retrolambdaDefaultMethods", required = true)
     public boolean defaultMethods;
 
+    /**
+     * Reduces the amount of logging.
+     *
+     * @since 2.4.0
+     */
+    @Parameter(defaultValue = "false", property = "retrolambdaQuiet", required = true)
+    public boolean quiet;
+
     /**
      * Forces Retrolambda to run in a separate process. The default is not to fork,
      * in which case Maven has to run under Java 8, or this plugin will fall back
@@ -128,6 +136,7 @@ private void processClassesInCurrentProcess() throws MojoExecutionException {
             Properties p = new Properties();
             p.setProperty(SystemPropertiesConfig.BYTECODE_VERSION, "" + targetBytecodeVersions.get(target));
             p.setProperty(SystemPropertiesConfig.DEFAULT_METHODS, "" + defaultMethods);
+            p.setProperty(SystemPropertiesConfig.QUIET, "" + quiet);
             p.setProperty(SystemPropertiesConfig.INPUT_DIR, getInputDir().getAbsolutePath());
             p.setProperty(SystemPropertiesConfig.OUTPUT_DIR, getOutputDir().getAbsolutePath());
             p.setProperty(SystemPropertiesConfig.CLASSPATH, getClasspath());
@@ -159,6 +168,7 @@ private void processClassesInForkedProcess() throws MojoExecutionException {
                                             attribute("failonerror", "true")),
                                     element("arg", attribute("value", "-Dretrolambda.bytecodeVersion=" + targetBytecodeVersions.get(target))),
                                     element("arg", attribute("value", "-Dretrolambda.defaultMethods=" + defaultMethods)),
+                                    element("arg", attribute("value", "-Dretrolambda.quiet=" + quiet)),
                                     element("arg", attribute("value", "-Dretrolambda.inputDir=" + getInputDir().getAbsolutePath())),
                                     element("arg", attribute("value", "-Dretrolambda.outputDir=" + getOutputDir().getAbsolutePath())),
                                     element("arg", attribute("value", "-Dretrolambda.classpathFile=" + classpathFile)),

retrolambda/src/main/java/net/orfjackal/retrolambda/Config.java

@@ -1,4 +1,4 @@
-// Copyright © 2013-2015 Esko Luontola <www.orfjackal.net>
+// Copyright © 2013-2017 Esko Luontola and other Retrolambda contributors
 // This software is released under the Apache License 2.0.
 // The license text is at http://www.apache.org/licenses/LICENSE-2.0
 
@@ -20,4 +20,6 @@ public interface Config {
     List<Path> getClasspath();
 
     List<Path> getIncludedFiles();
+
+    boolean isQuiet();
 }

retrolambda/src/main/java/net/orfjackal/retrolambda/Retrolambda.java

@@ -24,6 +24,11 @@ public static void run(Config config) throws Throwable {
         Path outputDir = config.getOutputDir();
         List<Path> classpath = config.getClasspath();
         List<Path> includedFiles = config.getIncludedFiles();
+        if (config.isQuiet()) {
+            Log.WARN();
+        } else {
+            Log.INFO();
+        }
         Log.info("Bytecode version: " + bytecodeVersion + " (" + Bytecode.getJavaVersion(bytecodeVersion) + ")");
         Log.info("Default methods:  " + defaultMethodsEnabled);
         Log.info("Input directory:  " + inputDir);

retrolambda/src/main/java/net/orfjackal/retrolambda/SystemPropertiesConfig.java

@@ -1,4 +1,4 @@
-// Copyright © 2013-2016 Esko Luontola and other Retrolambda contributors
+// Copyright © 2013-2017 Esko Luontola and other Retrolambda contributors
 // This software is released under the Apache License 2.0.
 // The license text is at http://www.apache.org/licenses/LICENSE-2.0
 
@@ -22,6 +22,7 @@ public class SystemPropertiesConfig implements Config {
     public static final String CLASSPATH_FILE = CLASSPATH + "File";
     public static final String INCLUDED_FILES = PREFIX + "includedFiles";
     public static final String INCLUDED_FILES_FILE = INCLUDED_FILES + "File";
+    public static final String QUIET = PREFIX + "quiet";
 
     private static final List<String> requiredProperties = new ArrayList<>();
     private static final Map<String, String> alternativeProperties = new HashMap<>();
@@ -199,6 +200,21 @@ public List<Path> getIncludedFiles() {
     }
 
 
+    // quiet
+
+    static {
+        optionalParameterHelp(QUIET,
+                "Reduces the amount of logging.",
+                "Disabled by default. Enable by setting to \"true\"");
+
+    }
+
+    @Override
+    public boolean isQuiet() {
+        return Boolean.parseBoolean(p.getProperty(QUIET, "false"));
+    }
+
+
     // help
 
     public String getHelp() {
@@ -212,7 +228,7 @@ public String getHelp() {
                 "some other language features to work on Java 7, 6 or 5.\n" +
                 "Web site: https://github.com/orfjackal/retrolambda\n" +
                 "\n" +
-                "Copyright (c) 2013-2016  Esko Luontola and other Retrolambda contributors\n" +
+                "Copyright (c) 2013-2017  Esko Luontola and other Retrolambda contributors\n" +
                 "This software is released under the Apache License 2.0.\n" +
                 "The license text is at http://www.apache.org/licenses/LICENSE-2.0\n" +
                 "\n" +