Java在指定路径上创建文件，所在文件夹不存在时，如何解决

String strPath = "d:\upload\file\2.mp3";
File file = new File(strPath);
if(!file.exists())){
    file.createNewFile();
}

String strPath = "d:\upload\file\2.mp3";
File file = new File(strPath);
if(!file.exists())){
    file.file.mkdirs();
}

String strPath = "d:\upload\file\2.mp3";
File file = new File(strPath);
File fileParent = file.getParentFile();
if(!fileParent.exists()){
    fileParent.mkdirs();
}
file.createNewFile();