Delphi把IO相关的都提取到System.IoUtils单元中。
路径操作使用TPath的方法都很方便。
uses System.IoUtils

TPath.GetTempPath//临时目录
TPath.GetCameraPath//照相机目录(照片/录像)
TPath.GetMusicPath//音乐目录
TPath.GetDownloadsPath//下载目录
……
如果使用TPath类的静态方法那么代码就是跨平台的，在Windows,Mac,iOS,Android上都能用。如果仅仅对Android的操作也可以使用Androidapi.IOUtils单元的那些GetXX的函数，也很简单，都没有参数，并且返回值都是字符串。

可以用任何一个事件测试一下：
   showmessage('GetCachePath:' + TPath.GetPathRoot(TPath.GetCachePath));
   showmessage('GetTempPath:' + TPath.GetTempPath);
   showmessage('GetHomePath:' + TPath.GetHomePath);
   showmessage('GetDocumentsPath:' + TPath.GetDocumentsPath);    showmessage('GetSharedDocumentsPath:' + TPath.GetSharedDocumentsPath);
   showmessage('GetSharedPicturesPath:' + TPath.GetSharedPicturesPath);
   showmessage('GetSharedDownloadsPath:' + TPath.GetSharedDownloadsPath);
   showmessage('GetCachePath:' + TPath.GetCachePath);
   showmessage('GetCameraPath:' + TPath.GetCameraPath);
   showmessage('GetPicturesPath:' + TPath.GetPicturesPath);
   showmessage('GetPublicPath:' + TPath.GetPublicPath);
以下是用nubia z5手机测试的结果（都是TPath下的函数，最后都没有/）：
GetRandomFileName:L8d4hdw0.W2d
GetTempFileName:/storage/sdcard0/Android/data/com.embarcadero.Project1/files/tmp/tmp.qqvwf21410
GetTempPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files/tmp
GetHomePath:/data/data/com.embarcadero.Project1/files
GetDocumentsPath:/data/data/com.embarcadero.Project1/files
GetSharedDocumentsPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files
GetLibraryPath:/data/app-lib/com.embarcadero.Project1-2
GetCachePath:/data/data/com.embarcadero.Project1/cache
GetPublicPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files
GetPicturesPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files/Pictures
GetSharedPicturesPath:/storage/sdcard0/Pictures
GetCameraPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files/DCIM
GetSharedCameraPath:/storage/sdcard0/DCIM
GetMusicPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files/Music
GetSharedMusicPath:/storage/sdcard0/Music
GetMoviesPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files/Movies
GetAlarmsPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files/Alarms
GetSharedAlarmsPath:/storage/sdcard0/Alarms
GetDownloadsPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files/Download
GetSharedDownloadsPath:/storage/sdcard0/Download
GetRingtonesPath:/storage/sdcard0/Android/data/com.embarcadero.Project1/files/Ringtones
GetSharedRingtonesPath:/storage/sdcard0/Ringtones