怎么区分Android storage USB memory和 Sdcard

如何区分Android storage USB memory和 Sdcard
由于现在做平板开发，必须得分出这2个存储。
USB memory和 sdcard
一般就看Enviroment类的源码。

public static File getExternalStorageDirectory() {// Try to be smarter// Return EXTERNAL_STORAGE_DIRECTORY_SD if SD card is ready// Return EXTERNAL_STORAGE_DIRECTORY_UDISK if SD card is absent but udisk is ready // Return EXTERNAL_STORAGE_DIRECTORY_SD if both sd card and udisk are not ready         String propSD = SystemProperties.get("EXTERNAL_STORAGE_STATE_SD", MEDIA_REMOVED);        String propUDISK = SystemProperties.get("EXTERNAL_STORAGE_STATE_UDISK", MEDIA_REMOVED);        String propEXTSD = SystemProperties.get("EXTERNAL_STORAGE_STATE_EXTSD", MEDIA_REMOVED);if (propSD.equals(MEDIA_MOUNTED) || propSD.equals(MEDIA_MOUNTED_READ_ONLY)) {    return EXTERNAL_STORAGE_DIRECTORY_SD;} else if (propUDISK.equals(MEDIA_MOUNTED) || propUDISK.equals(MEDIA_MOUNTED_READ_ONLY)) {    return EXTERNAL_STORAGE_DIRECTORY_UDISK;} else if (propEXTSD.equals(MEDIA_MOUNTED) || propEXTSD.equals(MEDIA_MOUNTED_READ_ONLY)) {    return EXTERNAL_STORAGE_DIRECTORY_EXTSD;                } else {    return EXTERNAL_STORAGE_DIRECTORY_SD;}     }

然后

 Environment.getExternalStorageDirectory().getAbsolutePath()

看返回的是"/sdcard"还是"/udisk"既可。
如果你直接指定这2个路径，去得到里面的文件时，是错误的！因为android里面默认会有/sdcard和/udisk目录，也就是说，你必须监听MEDIA_MOUNTED之后去Environment.getExternalStorageDirectory().getAbsolutePath()来判断路径！