In Android, Environment and StatFs obtain the size of the system/SDCard storage space, statfssdcard

In Android, Environment and StatFs obtain the size of the system/SDCard storage space, statfssdcard

I recently remembered the knowledge of Android development. I haven't used it for a long time, and I forgot about it. I checked the information for a while and found it back. By the way, I wrote it down to help students who needed it.

First, let's talk about the Environment and StatFs classes, and then introduce their detailed usage methods.

1. Environment class:
Environment is a class that provides access to Environment variables.
Environment contains constants:
MEDIA_BAD_REMOVAL
Explanation: getExternalStorageState () is returned, indicating that the SDCard has been removed before it is detached.
MEDIA_CHECKING
Explanation: getExternalStorageState () is returned, indicating that the object is checking the disk.
MEDIA_MOUNTED
Explanation: getExternalStorageState () is returned, indicating whether the object exists and has read/write permissions.
MEDIA_MOUNTED_READ_ONLY
Explanation: getExternalStorageState () is returned, indicating that the object permission is read-only.
MEDIA_NOFS
Explanation: getExternalStorageState () is returned, indicating that the object is blank or unsupported file system is being used.
MEDIA_REMOVED
Explanation: getExternalStorageState () is returned. If no SDCard exists
MEDIA_SHARED
Explanation: getExternalStorageState () is returned. If the SDCard is not installed and shared by USB
MEDIA_UNMOUNTABLE
Explanation: getExternalStorageState () is returned, and SDCard cannot be installed if it exists but cannot be installed.
MEDIA_UNMOUNTED
Explanation: getExternalStorageState () is returned, and the SDCard has been detached. If the SDCard exists but is not installed
Common Environment methods:
Method: getDataDirectory ()
Explanation: return a File to obtain the Android data directory.
Method: getDownloadCacheDirectory ()
Explanation: return a File to obtain the Android download/cache content directory.
Method: getExternalStorageDirectory ()
Explanation: The returned File gets the external storage directory, that is, SDCard.
Method: getExternalStoragePublicDirectory (String type)
Explanation: The returned File is a high-end public external memory directory to place some types of files.
Method: getExternalStorageState ()
Explanation: returns a File to obtain the current status of the external storage device.
Method: getRootDirectory ()
Explanation: returns a File to obtain the Android root directory.
2. StatFs class:
StatFs is a class that simulates df commands in linux to obtain the usage of SD card and mobile phone memory.
Common StatFs methods:
GetAvailableBlocks ()
Explanation: Int is returned to obtain the currently available bucket.
GetBlockCount ()
Explanation: Int is returned to obtain the number of available file systems in the region.
GetBlockSize ()
Explanation: Int is returned, in bytes. It is a file system.
GetFreeBlocks ()
Explanation: Int is returned, indicating the remaining space in the block area.
Restat (String path)
Explanation: execute a file system referenced by this object.

/** When storing files, you usually need to know the storage size inside the system or sdcard to ensure sufficient available space. The following provides a tool class */

Package com. neverno. util;


Import java. io. File;


Import android. OS. Environment;
Import android. OS. StatFs;


Public class MemoryStatus {
Static final int ERROR =-1;


/**
* Whether external storage is available
* @ Return
*/
Static public boolean externalMemoryAvailable (){
Return android. OS. Environment. getExternalStorageState (). equals (
Android. OS. Environment. MEDIA_MOUNTED );
}


/**
* Obtain the internal available space of the mobile phone.
* @ Return
*/
Static public long getAvailableInternalMemorySize (){
File path = Environment. getDataDirectory ();
StatFs stat = new StatFs (path. getPath ());
Long blockSize = stat. getBlockSize ();
Long availableBlocks = stat. getAvailableBlocks ();
Return availableBlocks * blockSize;
}


/**
* Obtain the internal space of the mobile phone.
* @ Return
*/
Static public long getTotalInternalMemorySize (){
File path = Environment. getDataDirectory ();
StatFs stat = new StatFs (path. getPath ());
Long blockSize = stat. getBlockSize ();
Long totalBlocks = stat. getBlockCount ();
Return totalBlocks * blockSize;
}


/**
* Obtain the external available space of the mobile phone
* @ Return
*/
Static public long getAvailableExternalMemorySize (){
If (externalMemoryAvailable ()){
File path = Environment. getExternalStorageDirectory ();
StatFs stat = new StatFs (path. getPath ());
Long blockSize = stat. getBlockSize ();
Long availableBlocks = stat. getAvailableBlocks ();
Return availableBlocks * blockSize;
} Else {
Return ERROR;
}
}


/**
* Obtain the external space of the mobile phone.
* @ Return
*/
Static public long getTotalExternalMemorySize (){
If (externalMemoryAvailable ()){
File path = Environment. getExternalStorageDirectory ();
StatFs stat = new StatFs (path. getPath ());
Long blockSize = stat. getBlockSize ();
Long totalBlocks = stat. getBlockCount ();
Return totalBlocks * blockSize;
} Else {
Return ERROR;
}
}


Static public String formatSize (long size ){
String suffix = null;


If (size> = 1024 ){
Suffix = "KiB ";
Size/= 1024;
If (size> = 1024 ){
Suffix = "MiB ";
Size/= 1024;
}
}


StringBuilder resultBuffer = new StringBuilder (Long. toString (size ));
Int commaOffset = resultBuffer. length ()-3;
While (commaOffset> 0 ){
ResultBuffer. insert (commaOffset ,',');
CommaOffset-= 3;
}


If (suffix! = Null)
ResultBuffer. append (suffix );
Return resultBuffer. toString ();
}
}