Environment所得到的文件目录

r囧r小猫 2023-10-16 18:52 15阅读 0赞

Android 中，Environment类提供了一些函数来得到文件系统中一些目录，以下是一些例子，

File f1 = Environment.getDataDirectory();

File f2 = Environment.getDownloadCacheDirectory();

File f3 = Environment.getRootDirectory();

File f4= Environment.getExternalStorageDirectory();

// 结果：

f1.getPath() ； // /data

f2.getPath()； // /cache

f3.getPath()； // /system

f4.getPath()； // /mnt/sdcard

附：Environment 源码（android2.2）：

/\*\*  
\* Provides access to environment variables.  
\*/  
public class Environment \{  
  
  
private static final File ROOT\_DIRECTORY  
= getDirectory("ANDROID\_ROOT", "/system");  
  
  
/\*\*  
\* Gets the Android root directory.  
\*/  
public static File getRootDirectory() \{  
return ROOT\_DIRECTORY;  
\}  
  
  
private static final File DATA\_DIRECTORY  
= getDirectory("ANDROID\_DATA", "/data");  
  
  
private static final File EXTERNAL\_STORAGE\_DIRECTORY  
= getDirectory("EXTERNAL\_STORAGE", "/sdcard");  
  
  
private static final File DOWNLOAD\_CACHE\_DIRECTORY  
= getDirectory("DOWNLOAD\_CACHE", "/cache");  
  
  
/\*\*  
\* Gets the Android data directory.  
\*/  
public static File getDataDirectory() \{  
return DATA\_DIRECTORY;  
\}  
  
  
/\*\*  
\* Gets the Android external storage directory.  
\*/  
public static File getExternalStorageDirectory() \{  
return EXTERNAL\_STORAGE\_DIRECTORY;  
\}  
  
  
/\*\*  
\* Gets the Android Download/Cache content directory.  
\*/  
public static File getDownloadCacheDirectory() \{  
return DOWNLOAD\_CACHE\_DIRECTORY;  
\}  
  
  
/\*\*  
\* getExternalStorageState() returns MEDIA\_REMOVED if the media is not present.  
\*/  
public static final String MEDIA\_REMOVED = "removed";  
  
/\*\*  
\* getExternalStorageState() returns MEDIA\_UNMOUNTED if the media is present  
\* but not mounted.  
\*/  
public static final String MEDIA\_UNMOUNTED = "unmounted";  
  
  
/\*\*  
\* getExternalStorageState() returns MEDIA\_CHECKING if the media is present  
\* and being disk-checked  
\*/  
public static final String MEDIA\_CHECKING = "checking";  
  
  
/\*\*  
\* getExternalStorageState() returns MEDIA\_NOFS if the media is present  
\* but is blank or is using an unsupported filesystem  
\*/  
public static final String MEDIA\_NOFS = "nofs";  
  
  
/\*\*  
\* getExternalStorageState() returns MEDIA\_MOUNTED if the media is present  
\* and mounted at its mount point with read/write access.  
\*/  
public static final String MEDIA\_MOUNTED = "mounted";  
  
  
/\*\*  
\* getExternalStorageState() returns MEDIA\_MOUNTED\_READ\_ONLY if the media is present  
\* and mounted at its mount point with read only access.  
\*/  
public static final String MEDIA\_MOUNTED\_READ\_ONLY = "mounted\_ro";  
  
  
/\*\*  
\* getExternalStorageState() returns MEDIA\_SHARED if the media is present  
\* not mounted, and shared via USB mass storage.  
\*/  
public static final String MEDIA\_SHARED = "shared";  
  
  
/\*\*  
\* getExternalStorageState() returns MEDIA\_BAD\_REMOVAL if the media was  
\* removed before it was unmounted.  
\*/  
public static final String MEDIA\_BAD\_REMOVAL = "bad\_removal";  
  
  
/\*\*  
\* getExternalStorageState() returns MEDIA\_UNMOUNTABLE if the media is present  
\* but cannot be mounted. Typically this happens if the file system on the  
\* media is corrupted.  
\*/  
public static final String MEDIA\_UNMOUNTABLE = "unmountable";  
  
  
/\*\*  
\* Gets the current state of the external storage device.  
\*/  
public static String getExternalStorageState() \{  
return SystemProperties.get("EXTERNAL\_STORAGE\_STATE", MEDIA\_REMOVED);  
\}  
  
  
static File getDirectory(String variableName, String defaultPath) \{  
String path = System.getenv(variableName);  
return path == null ? new File(defaultPath) : new File(path);  
\}  
\}