Java 的 createNewFile()-它也会创建目录吗？

No.
Use tmp.getParentFile().mkdirs() before you create the file.

File theDir = new File(DirectoryPath);
if (!theDir.exists()) theDir.mkdirs();

File directory = new File(tmp.getParentFile().getAbsolutePath());
directory.mkdirs();

If the directories already exist, nothing will happen, so you don't need any checks.

StringUtils.touch(/path/filename.ext) will now (>=1.3) also create the directory and file if they don't exist.

Java 8 Style

Path path = Paths.get("logs/error.log");
Files.createDirectories(path.getParent());

To write on file

Files.write(path, "Log log".getBytes());

To read

System.out.println(Files.readAllLines(path));

Full example

public class CreateFolderAndWrite {


public static void main(String[] args) {
try {
Path path = Paths.get("logs/error.log");
Files.createDirectories(path.getParent());


Files.write(path, "Log log".getBytes());


System.out.println(Files.readAllLines(path));
} catch (IOException e) {
e.printStackTrace();
}
}
}

No, and if logs does not exist you'll receive java.io.IOException: No such file or directory

Fun fact for android devs: calls the likes of Files.createDirectories() and Paths.get() would work when supporting min api 26.