如果你需要一个临时目录进行测试，并且你正在使用jUnit， @Rule和TemporaryFolder可以解决你的问题:

@Rule
public TemporaryFolder folder = new TemporaryFolder();

从文档中可以看到:

TemporaryFolder规则允许创建文件和文件夹，这些文件和文件夹保证在测试方法完成时被删除(无论它通过还是失败)。

更新:

如果您正在使用JUnit Jupiter(版本5.1.1或更高)，您可以选择使用JUnit Pioneer，它是JUnit 5扩展包。

摘自项目文档:

例如，下面的测试为单个测试方法注册扩展名，创建一个文件并将其写入临时目录，并检查其内容。

@Test
@ExtendWith(TempDirectory.class)
void test(@TempDir Path tempDir) {
    Path file = tempDir.resolve("test.txt");
    writeFile(file);
    assertExpectedFileContent(file);
}

更多信息在JavaDoc和TempDirectory的JavaDoc中

Gradle:

dependencies {
    testImplementation 'org.junit-pioneer:junit-pioneer:0.1.2'
}

Maven:

<dependency>
   <groupId>org.junit-pioneer</groupId>
   <artifactId>junit-pioneer</artifactId>
   <version>0.1.2</version>
   <scope>test</scope>
</dependency>

更新2:

@TempDir注释作为实验特性被添加到JUnit Jupiter 5.4.0发行版中。示例摘自JUnit 5用户指南:

@Test
void writeItemsToFile(@TempDir Path tempDir) throws IOException {
    Path file = tempDir.resolve("test.txt");

    new ListWriter(file).write("a", "b", "c");

    assertEquals(singletonList("a,b,c"), Files.readAllLines(file));
}

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)
            + ')');
  }

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。

从Java 1.7开始，createTempDirectory(prefix, attrs)和createTempDirectory(dir, prefix, attrs)包含在Java .nio.file. files中

操作: 寺庙文件。

在Java 7之前，你还可以:

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

这是Guava库的Files.createTempDir()的源代码。它没有你想象的那么复杂:

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) + ')');
}

默认情况下:

private static final int TEMP_DIR_ATTEMPTS = 10000;

在这里看到的