是否有一种在Java应用程序中创建临时目录的标准而可靠的方法?在Java的问题数据库中有一个条目,在评论中有一些代码,但我想知道在一个常用的库(Apache Commons等)中是否有一个标准的解决方案?


当前回答

使用file# createTempFile和delete为目录创建一个唯一的名称似乎是可以的。您应该添加一个ShutdownHook,以便在JVM关闭时(递归地)删除目录。

其他回答

正如本RFE及其注释中所讨论的,您可以首先调用tempDir.delete()。或者你可以使用System.getProperty("java.io.tmpdir")并在那里创建一个目录。无论采用哪种方法,都应该记得调用tempDir.deleteOnExit(),否则在完成操作后文件将不会被删除。

在Java 7之前,你还可以:

File folder = File.createTempFile("testFileUtils", ""); // no suffix
folder.delete();
folder.mkdirs();
folder.deleteOnExit();

只是为了完成,这是谷歌番石榴库的代码。这不是我的代码,但我认为在这个线程中展示它是有价值的。

  /** Maximum loop count when creating temp directories. */
  private static final int TEMP_DIR_ATTEMPTS = 10000;

  /**
   * Atomically creates a new directory somewhere beneath the system's temporary directory (as
   * defined by the {@code java.io.tmpdir} system property), and returns its name.
   *
   * <p>Use this method instead of {@link File#createTempFile(String, String)} when you wish to
   * create a directory, not a regular file. A common pitfall is to call {@code createTempFile},
   * delete the file and create a directory in its place, but this leads a race condition which can
   * be exploited to create security vulnerabilities, especially when executable files are to be
   * written into the directory.
   *
   * <p>This method assumes that the temporary volume is writable, has free inodes and free blocks,
   * and that it will not be called thousands of times per second.
   *
   * @return the newly-created directory
   * @throws IllegalStateException if the directory could not be created
   */
  public static File createTempDir() {
    File baseDir = new File(System.getProperty("java.io.tmpdir"));
    String baseName = System.currentTimeMillis() + "-";

    for (int counter = 0; counter < TEMP_DIR_ATTEMPTS; counter++) {
      File tempDir = new File(baseDir, baseName + counter);
      if (tempDir.mkdir()) {
        return tempDir;
      }
    }
    throw new IllegalStateException(
        "Failed to create directory within "
            + TEMP_DIR_ATTEMPTS
            + " attempts (tried "
            + baseName
            + "0 to "
            + baseName
            + (TEMP_DIR_ATTEMPTS - 1)
            + ')');
  }

试试这个小例子:

代码:

try {
    Path tmpDir = Files.createTempDirectory("tmpDir");
    System.out.println(tmpDir.toString());
    Files.delete(tmpDir);
} catch (IOException e) {
    e.printStackTrace();
}

进口: java.io.IOException java.nio.file.Files java.nio.file.Path

Windows机器上的控制台输出: C:\Users\userName\AppData\Local\Temp\ tmpDir2908538301081367877

备注: 文件。createTempDirectory自动生成唯一ID - 2908538301081367877。 注意: 阅读以下递归删除目录的方法: 在Java中递归地删除目录

这段代码应该可以很好地工作:

public static File createTempDir() {
    final String baseTempPath = System.getProperty("java.io.tmpdir");

    Random rand = new Random();
    int randomInt = 1 + rand.nextInt();

    File tempDir = new File(baseTempPath + File.separator + "tempDir" + randomInt);
    if (tempDir.exists() == false) {
        tempDir.mkdir();
    }

    tempDir.deleteOnExit();

    return tempDir;
}