Refactor loggers and make Checker a final, non abstract class

src/main/java/de/thetaphi/forbiddenapis/AbstractCheckMojo.java

@@ -215,22 +215,19 @@ public void execute() throws MojoExecutionException, MojoFailureException {
       if (failOnMissingClasses) options.add(FAIL_ON_MISSING_CLASSES);
       if (failOnViolation) options.add(FAIL_ON_VIOLATION);
       if (failOnUnresolvableSignatures) options.add(FAIL_ON_UNRESOLVABLE_SIGNATURES);
-      final Checker checker = new Checker(loader, options) {
-        @Override
-        protected void logError(String msg) {
+      final Checker checker = new Checker(new Logger() {
+        public void error(String msg) {
           log.error(msg);
         }
 
-        @Override
-        protected void logWarn(String msg) {
+        public void warn(String msg) {
           log.warn(msg);
         }
 
-        @Override
-        protected void logInfo(String msg) {
+        public void info(String msg) {
           log.info(msg);
         }
-      };
+      }, loader, options);
 
       if (!checker.isSupportedJDK) {
         final String msg = String.format(Locale.ENGLISH, 

src/main/java/de/thetaphi/forbiddenapis/AntTask.java

@@ -85,23 +85,20 @@ public void execute() throws BuildException {
       if (failOnMissingClasses) options.add(FAIL_ON_MISSING_CLASSES);
       if (failOnViolation) options.add(FAIL_ON_VIOLATION);
       if (failOnUnresolvableSignatures) options.add(FAIL_ON_UNRESOLVABLE_SIGNATURES);
-      final Checker checker = new Checker(loader, options) {
-        @Override
-        protected void logError(String msg) {
+      final Checker checker = new Checker(new Logger() {
+        public void error(String msg) {
           log(msg, Project.MSG_ERR);
         }
 
-        @Override
-        protected void logWarn(String msg) {
+        public void warn(String msg) {
           // ANT has no real log levels printed, so prefix with "WARNING":
           log("WARNING: " + msg, Project.MSG_WARN);
         }
 
-        @Override
-        protected void logInfo(String msg) {
+        public void info(String msg) {
           log(msg, Project.MSG_INFO);
         }
-      };
+      }, loader, options);
 
       if (!checker.isSupportedJDK) {
         final String msg = String.format(Locale.ENGLISH, 

src/main/java/de/thetaphi/forbiddenapis/Checker.java

@@ -56,7 +56,7 @@
  * and the system classloader. It uses the local classpath in preference to the system classpath
  * (which violates the spec).
  */
-public abstract class Checker implements RelatedClassLookup {
+public final class Checker implements RelatedClassLookup {
 
   public static enum Option {
     INTERNAL_RUNTIME_FORBIDDEN,
@@ -69,6 +69,8 @@ public static enum Option {
 
   private final long start;
 
+  final Logger logger;
+
   final Set<File> bootClassPathJars;
   final Set<String> bootClassPathDirs;
   final ClassLoader loader;
@@ -90,15 +92,12 @@ public static enum Option {
   // descriptors (not internal names) of all annotations that suppress:
   final Set<String> suppressAnnotations = new LinkedHashSet<String>();
 
-  protected abstract void logError(String msg);
-  protected abstract void logWarn(String msg);
-  protected abstract void logInfo(String msg);
-
-  public Checker(ClassLoader loader, Option... options) {
-    this(loader, (options.length == 0) ? EnumSet.noneOf(Option.class) : EnumSet.copyOf(Arrays.asList(options)));
+  public Checker(Logger logger, ClassLoader loader, Option... options) {
+    this(logger, loader, (options.length == 0) ? EnumSet.noneOf(Option.class) : EnumSet.copyOf(Arrays.asList(options)));
   }
 
-  public Checker(ClassLoader loader, EnumSet<Option> options) {
+  public Checker(Logger logger, ClassLoader loader, EnumSet<Option> options) {
+    this.logger = logger;
     this.loader = loader;
     this.options = options;
     this.start = System.currentTimeMillis();
@@ -228,7 +227,7 @@ public ClassSignature lookupRelatedClass(String internalName) {
       if (options.contains(Option.FAIL_ON_MISSING_CLASSES)) {
         throw new WrapperRuntimeException(cnfe);
       } else {
-        logWarn(String.format(Locale.ENGLISH,
+        logger.warn(String.format(Locale.ENGLISH,
           "The referenced class '%s' cannot be loaded. Please fix the classpath!",
           type.getClassName()
         ));
@@ -241,7 +240,7 @@ private void reportParseFailed(boolean failOnUnresolvableSignatures, String mess
     if (failOnUnresolvableSignatures) {
       throw new ParseException(String.format(Locale.ENGLISH, "%s while parsing signature: %s", message, signature));
     } else {
-      logWarn(String.format(Locale.ENGLISH, "%s while parsing signature: %s [signature ignored]", message, signature));
+      logger.warn(String.format(Locale.ENGLISH, "%s while parsing signature: %s [signature ignored]", message, signature));
     }
   }
 
@@ -428,7 +427,7 @@ private int checkClass(final ClassReader reader, Pattern suppressAnnotationsPatt
     final Pattern splitter = Pattern.compile(Pattern.quote("\n"));
     for (final ForbiddenViolation v : violations) {
       for (final String line : splitter.split(v.format(className, scanner.getSourceFile()))) {
-        logError(line);
+        logger.error(line);
       }
     }
     return violations.size();
@@ -450,10 +449,10 @@ public final void run() throws ForbiddenApiException {
         "Scanned %d (and %d related) class file(s) for forbidden API invocations (in %.2fs), %d error(s).",
         classesToCheck.size(), classesToCheck.isEmpty() ? 0 : classpathClassCache.size(), (System.currentTimeMillis() - start) / 1000.0, errors);
     if (options.contains(Option.FAIL_ON_VIOLATION) && errors > 0) {
-      logError(message);
+      logger.error(message);
       throw new ForbiddenApiException("Check for forbidden API calls failed, see log.");
     } else {
-      logInfo(message);
+      logger.info(message);
     }
   }
 

src/main/java/de/thetaphi/forbiddenapis/CliMain.java

@@ -51,6 +51,8 @@ public final class CliMain {
     internalruntimeforbiddenOpt, allowmissingclassesOpt, allowunresolvablesignaturesOpt, versionOpt, helpOpt;
   private final CommandLine cmd;
 
+  private static final Logger LOG = StdIoLogger.INSTANCE;
+
   public static final int EXIT_SUCCESS = 0;
   public static final int EXIT_VIOLATION = 1;
   public static final int EXIT_ERR_CMDLINE = 2;
@@ -148,24 +150,9 @@ public CliMain(String... args) throws ExitException {
     }
   }
 
-  @SuppressForbidden
-  void logError(String msg) {
-    System.err.println("ERROR: " + msg);
-  }
-
-  @SuppressForbidden
-  void logWarn(String msg) {
-    System.err.println("WARNING: " + msg);
-  }
-
-  @SuppressForbidden
-  void logInfo(String msg) {
-    System.out.println(msg);
-  }
-
   private void printVersion() {
     final Package pkg = this.getClass().getPackage();
-    logInfo(String.format(Locale.ENGLISH,
+    LOG.info(String.format(Locale.ENGLISH,
       "%s %s",
       pkg.getImplementationTitle(), pkg.getImplementationVersion()
     ));
@@ -227,22 +214,7 @@ public void run() throws ExitException {
       if (cmd.hasOption(internalruntimeforbiddenOpt.getLongOpt())) options.add(INTERNAL_RUNTIME_FORBIDDEN);
       if (!cmd.hasOption(allowmissingclassesOpt.getLongOpt())) options.add(FAIL_ON_MISSING_CLASSES);
       if (!cmd.hasOption(allowunresolvablesignaturesOpt.getLongOpt())) options.add(FAIL_ON_UNRESOLVABLE_SIGNATURES);
-      final Checker checker = new Checker(loader, options) {
-        @Override
-        protected void logError(String msg) {
-          CliMain.this.logError(msg);
-        }
-
-        @Override
-        protected void logWarn(String msg) {
-          CliMain.this.logWarn(msg);
-        }
-
-        @Override
-        protected void logInfo(String msg) {
-          CliMain.this.logInfo(msg);
-        }
-      };
+      final Checker checker = new Checker(LOG, loader, options);
 
       if (!checker.isSupportedJDK) {
         throw new ExitException(EXIT_UNSUPPORTED_JDK, String.format(Locale.ENGLISH, 
@@ -255,7 +227,7 @@ protected void logInfo(String msg) {
         checker.addSuppressAnnotation(a);
       }
 
-      logInfo("Scanning for classes to check...");
+      LOG.info("Scanning for classes to check...");
       if (!classesDirectory.exists()) {
         throw new ExitException(EXIT_ERR_OTHER, "Directory with class files does not exist: " + classesDirectory);
       }
@@ -281,13 +253,13 @@ protected void logInfo(String msg) {
       try {
         final String[] bundledSignatures = cmd.getOptionValues(bundledsignaturesOpt.getLongOpt());
         if (bundledSignatures != null) for (String bs : bundledSignatures) {
-          logInfo("Reading bundled API signatures: " + bs);
+          LOG.info("Reading bundled API signatures: " + bs);
           checker.parseBundledSignatures(bs, null);
         }
         final String[] signaturesFiles = cmd.getOptionValues(signaturesfileOpt.getLongOpt());
         if (signaturesFiles != null) for (String sf : signaturesFiles) {
           final File f = new File(sf).getAbsoluteFile();
-          logInfo("Reading API signatures: " + f);
+          LOG.info("Reading API signatures: " + f);
           checker.parseSignaturesFile(new FileInputStream(f));
         }
       } catch (IOException ioe) {
@@ -303,7 +275,7 @@ protected void logInfo(String msg) {
         ));
       }
 
-      logInfo("Loading classes to check...");
+      LOG.info("Loading classes to check...");
       try {
         for (String f : files) {
           checker.addClassToCheck(new FileInputStream(new File(classesDirectory, f)));
@@ -312,7 +284,7 @@ protected void logInfo(String msg) {
         throw new ExitException(EXIT_ERR_OTHER, "Failed to load one of the given class files: " + ioe);
       }
 
-      logInfo("Scanning for API signatures and dependencies...");
+      LOG.info("Scanning for API signatures and dependencies...");
       try {
         checker.run();
       } catch (ForbiddenApiException fae) {

src/main/java/de/thetaphi/forbiddenapis/Logger.java

@@ -0,0 +1,23 @@
+package de.thetaphi.forbiddenapis;
+
+/*
+ * (C) Copyright Uwe Schindler (Generics Policeman) and others.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public interface Logger {
+  abstract void error(String msg);
+  abstract void warn(String msg);
+  abstract void info(String msg);
+}

src/main/java/de/thetaphi/forbiddenapis/StdIoLogger.java

@@ -0,0 +1,38 @@
+package de.thetaphi.forbiddenapis;
+
+/*
+ * (C) Copyright Uwe Schindler (Generics Policeman) and others.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+@SuppressForbidden
+public final class StdIoLogger implements Logger {
+
+  public static final Logger INSTANCE = new StdIoLogger();
+
+  private StdIoLogger() {}
+
+  public void error(String msg) {
+    System.err.println("ERROR: " + msg);
+  }
+
+  public void warn(String msg) {
+    System.err.println("WARNING: " + msg);
+  }
+
+  public void info(String msg) {
+    System.out.println(msg);
+  }
+
+}

src/test/java/de/thetaphi/forbiddenapis/CheckerSetupTest.java

@@ -28,33 +28,11 @@
 
 public final class CheckerSetupTest {
 
-  @SuppressForbidden
-  static final class MyChecker extends Checker {
-    public MyChecker() {
-      super(ClassLoader.getSystemClassLoader(), INTERNAL_RUNTIME_FORBIDDEN, FAIL_ON_MISSING_CLASSES, FAIL_ON_VIOLATION, FAIL_ON_UNRESOLVABLE_SIGNATURES);
-    }
-
-    @Override
-    protected void logError(String msg) {
-      System.err.println("ERROR: " + msg);
-    }
-
-    @Override
-    protected void logWarn(String msg) {
-      System.err.println("WARN: " + msg);
-    }
-
-    @Override
-    protected void logInfo(String msg) {
-      System.err.println(msg);
-    }
-  }
-
   protected Checker checker;
 
   @Before
   public void setUp() {
-    checker = new MyChecker();
+    checker = new Checker(StdIoLogger.INSTANCE, ClassLoader.getSystemClassLoader(), INTERNAL_RUNTIME_FORBIDDEN, FAIL_ON_MISSING_CLASSES, FAIL_ON_VIOLATION, FAIL_ON_UNRESOLVABLE_SIGNATURES);
     assumeTrue("This test only works with a supported JDK (see docs)", checker.isSupportedJDK);
     assertEquals(EnumSet.of(INTERNAL_RUNTIME_FORBIDDEN, FAIL_ON_MISSING_CLASSES, FAIL_ON_VIOLATION, FAIL_ON_UNRESOLVABLE_SIGNATURES), checker.options);
   }
@@ -105,11 +83,7 @@ public void testMethodSignature() throws Exception {
 
   @Test
   public void testEmptyCtor() throws Exception {
-    Checker chk = new Checker(ClassLoader.getSystemClassLoader()) {
-      @Override protected void logError(String msg) { }
-      @Override protected void logWarn(String msg) { }
-      @Override protected void logInfo(String msg) { }
-    };
+    Checker chk = new Checker(StdIoLogger.INSTANCE, ClassLoader.getSystemClassLoader());
     assertEquals(EnumSet.noneOf(Checker.Option.class), chk.options);
   }