从 jar 文件中复制目录

感谢您的解决方案！对于其他人，以下内容不使用辅助类（StringUtils除外）

/我为此解决方案添加了额外的信息，检查代码的末尾，Zegor V/

public class FileUtils {
  public static boolean copyFile(final File toCopy, final File destFile) {
    try {
      return FileUtils.copyStream(new FileInputStream(toCopy),
          new FileOutputStream(destFile));
    } catch (final FileNotFoundException e) {
      e.printStackTrace();
    }
    return false;
  }

  private static boolean copyFilesRecusively(final File toCopy,
      final File destDir) {
    assert destDir.isDirectory();

    if (!toCopy.isDirectory()) {
      return FileUtils.copyFile(toCopy, new File(destDir, toCopy.getName()));
    } else {
      final File newDestDir = new File(destDir, toCopy.getName());
      if (!newDestDir.exists() && !newDestDir.mkdir()) {
        return false;
      }
      for (final File child : toCopy.listFiles()) {
        if (!FileUtils.copyFilesRecusively(child, newDestDir)) {
          return false;
        }
      }
    }
    return true;
  }

  public static boolean copyJarResourcesRecursively(final File destDir,
      final JarURLConnection jarConnection) throws IOException {

    final JarFile jarFile = jarConnection.getJarFile();

    for (final Enumeration<JarEntry> e = jarFile.entries(); e.hasMoreElements();) {
      final JarEntry entry = e.nextElement();
      if (entry.getName().startsWith(jarConnection.getEntryName())) {
        final String filename = StringUtils.removeStart(entry.getName(), //
            jarConnection.getEntryName());

        final File f = new File(destDir, filename);
        if (!entry.isDirectory()) {
          final InputStream entryInputStream = jarFile.getInputStream(entry);
          if(!FileUtils.copyStream(entryInputStream, f)){
            return false;
          }
          entryInputStream.close();
        } else {
          if (!FileUtils.ensureDirectoryExists(f)) {
            throw new IOException("Could not create directory: "
                + f.getAbsolutePath());
          }
        }
      }
    }
    return true;
  }

  public static boolean copyResourcesRecursively( //
      final URL originUrl, final File destination) {
    try {
      final URLConnection urlConnection = originUrl.openConnection();
      if (urlConnection instanceof JarURLConnection) {
        return FileUtils.copyJarResourcesRecursively(destination,
            (JarURLConnection) urlConnection);
      } else {
        return FileUtils.copyFilesRecusively(new File(originUrl.getPath()),
            destination);
      }
    } catch (final IOException e) {
      e.printStackTrace();
    }
    return false;
  }

  private static boolean copyStream(final InputStream is, final File f) {
    try {
      return FileUtils.copyStream(is, new FileOutputStream(f));
    } catch (final FileNotFoundException e) {
      e.printStackTrace();
    }
    return false;
  }

  private static boolean copyStream(final InputStream is, final OutputStream os) {
    try {
      final byte[] buf = new byte[1024];

      int len = 0;
      while ((len = is.read(buf)) > 0) {
        os.write(buf, 0, len);
      }
      is.close();
      os.close();
      return true;
    } catch (final IOException e) {
      e.printStackTrace();
    }
    return false;
  }

  private static boolean ensureDirectoryExists(final File f) {
    return f.exists() || f.mkdir();
  }
}

它只使用Apache软件基金会的一个外部库，但是使用的函数只有：

  public static String removeStart(String str, String remove) {
      if (isEmpty(str) || isEmpty(remove)) {
          return str;
      }
      if (str.startsWith(remove)){
          return str.substring(remove.length());
      }
      return str;
  }
  public static boolean isEmpty(CharSequence cs) {
      return cs == null || cs.length() == 0;
  }

我对Apache许可证的了解有限，但您可以在没有库的代码中使用此方法。但是，如果有的话，我不负责许可证问题。

使用Java7 +，这可以通过创建然后使用递归复制文件来实现。FileSystemwalkFileTree

public void copyFromJar(String source, final Path target) throws URISyntaxException, IOException {
    URI resource = getClass().getResource("").toURI();
    FileSystem fileSystem = FileSystems.newFileSystem(
            resource,
            Collections.<String, String>emptyMap()
    );


    final Path jarPath = fileSystem.getPath(source);

    Files.walkFileTree(jarPath, new SimpleFileVisitor<Path>() {

        private Path currentTarget;

        @Override
        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
            currentTarget = target.resolve(jarPath.relativize(dir).toString());
            Files.createDirectories(currentTarget);
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
            Files.copy(file, target.resolve(jarPath.relativize(file).toString()), StandardCopyOption.REPLACE_EXISTING);
            return FileVisitResult.CONTINUE;
        }

    });
}

该方法可以像这样使用：

copyFromJar("/path/to/the/template/in/jar", Paths.get("/tmp/from-jar"))