只是想向每个调用File.mkdir()或File.mkdirs()的人指出，要小心File对象是目录而不是文件。例如，如果你为路径/dir1/dir2/file.txt调用mkdirs()，它将创建一个名为file.txt的文件夹，这可能不是你想要的。如果你正在创建一个新文件，同时也想自动创建父文件夹，你可以这样做:

            File file = new File(filePath);
            if (file.getParentFile() != null) {
                file.getParentFile().mkdirs();
            }

对于java 7及以上版本:

Path path = Paths.get("/your/path/string");
Files.createDirectories(path);

在创建之前检查目录或文件是否存在似乎是不必要的，from createDirectories javadocs:

Creates a directory by creating all nonexistent parent directories first. Unlike the createDirectory method, an exception is not thrown if the directory could not be created because it already exists. The attrs parameter is optional file-attributes to set atomically when creating the nonexistent directories. Each file attribute is identified by its name. If more than one attribute of the same name is included in the array then all but the last occurrence is ignored. If this method fails, then it may do so after creating some, but not all, of the parent directories.

这是java的一个吸引力，使用短路或'||'，测试目录的存在，并为您制作目录

public File checkAndMakeTheDirectory() {
    File theDirectory = new File("/path/directory");
    if (theDirectory.exists() || theDirectory.mkdirs())
        System.out.println("The folder has been created or has been already there");
    return theDirectory;
}

如果If的第一部分为真，它不会运行第二部分，如果第一部分为假，它也会运行第二部分

在Java 7中，您可以使用Files.createDirectories()。

例如:

Files.createDirectories(Paths.get("/path/to/directory"));

该功能允许在用户的主目录上创建新目录。

private static void createDirectory(final String directoryName) {
    final File homeDirectory = new File(System.getProperty("user.home"));
    final File newDirectory = new File(homeDirectory, directoryName);
    if(!newDirectory.exists()) {
        boolean result = newDirectory.mkdir();

        if(result) {
            System.out.println("The directory is created !");
        }
    } else {
        System.out.println("The directory already exist");
    }
}

下面的方法可以做你想做的事情，只要确保你检查了mkdir() / mkdirs()的返回值

private void createUserDir(final String dirName) throws IOException {
    final File homeDir = new File(System.getProperty("user.home"));
    final File dir = new File(homeDir, dirName);
    if (!dir.exists() && !dir.mkdirs()) {
        throw new IOException("Unable to create " + dir.getAbsolutePath();
    }
}