Class Scanner

corpus/java/training/guava/reflect/ClassPath.java:326–448

Abstract class that scans through the class path represented by a ClassLoader and calls #scanDirectory and #scanJarFile for directories and jar files on the class path respectively.

   * respectively.
   */
  abstract static class Scanner {

    // We only scan each file once independent of the classloader that resource might be associated
    // with.
    private final Set<File> scannedUris = Sets.newHashSet();

    public final void scan(ClassLoader classloader) throws IOException {
      for (Map.Entry<File, ClassLoader> entry : getClassPathEntries(classloader).entrySet()) {
        scan(entry.getKey(), entry.getValue());
      }
    }

    /** Called when a directory is scanned for resource files. */
    protected abstract void scanDirectory(ClassLoader loader, File directory) throws IOException;

    /** Called when a jar file is scanned for resource entries. */
    protected abstract void scanJarFile(ClassLoader loader, JarFile file) throws IOException;

    @VisibleForTesting
    final void scan(File file, ClassLoader classloader) throws IOException {
      if (scannedUris.add(file.getCanonicalFile())) {
        scanFrom(file, classloader);
      }
    }

    private void scanFrom(File file, ClassLoader classloader) throws IOException {
      if (!file.exists()) {
        return;
      }
      if (file.isDirectory()) {
        scanDirectory(classloader, file);
      } else {
        scanJar(file, classloader);
      }
    }

    private void scanJar(File file, ClassLoader classloader) throws IOException {
      JarFile jarFile;
      try {
        jarFile = new JarFile(file);
      } catch (IOException e) {
        // Not a jar file
        return;
      }
      try {
        for (File path : getClassPathFromManifest(file, jarFile.getManifest())) {
          scan(path, classloader);
        }
        scanJarFile(classloader, jarFile);
      } finally {
        try {
          jarFile.close();
        } catch (IOException ignored) {
        }
      }
    }

    /**