I. Basic Concepts
Save a file in an Android application and save it in two places
① mobile phone with the storage space, small (such as 200M), suitable for saving some small files, Android save location in the data/data/application package name/files directory
② external storage devices such as SD cards, large, suitable for saving large files such as video, Android save location in Mnt/sdcard directory, androd1.5,android1.6 save in SDcard directory
Saved locations can be found by using the Android File Explorer view
Second, examples
Copy Code code as follows:
/**
* File Action Class
*
* @author XY
*
*/
public class Fileservice
{
/**
* Context Object
*/
private context;
Public Fileservice
{
Super ();
This.context = context;
}
/**
* Save the file to the phone's own storage space
*
* @param filename filename
* @param filecontent file contents
*/
@SuppressWarnings ("Static-access")
public void Save (string filename, String filecontent) throws Exception
{
FileOutputStream fos = context.openfileoutput (filename, context.) Mode_private); Default storage space saved on phone
Fos.write (Filecontent.getbytes ("UTF-8"));
Fos.close ();
}
/**
* Save file to sd card
*
* @param filename filename
* @param filecontent file contents
*/
public void Saveinsdcard (string filename, String filecontent) throws Exception
{
If the file is saved in SDcard, the file is not read-write control
File File = new file (environment.getexternalstoragedirectory (), filename);
FileOutputStream fos = new FileOutputStream (file);
Fos.write (Filecontent.getbytes ("UTF-8"));
Fos.close ();
}
/**
* Read the contents of the file
*
* @param filename filename
* @return
*/
Public String Read (String filename) throws Exception
{
FileInputStream FIS = context.openfileinput (filename);
Bytearrayoutputstream OutStream = new Bytearrayoutputstream ();
byte[] buffer = new byte[1024];
int len = 0;
Read the contents to the buffer and read to the end-1
while (len = fis.read (buffer))!=-1)
{
This example writes the contents of a byte array (buffer variable) to the memory buffer every time it is read to save the contents of each
Outstream.write (buffer, 0, Len);
}
Take the data saved in memory
byte[] data = Outstream.tobytearray ();
Fis.close ();
string result = new String (data, "UTF-8");
return result;
}
}
Mainactivity
Copy Code code as follows:
Try
{
stored in the cell phone with its own storage space
Fs.save (filename, filecontent);
Toast.maketext (Getapplicationcontext (), r.string.success, Toast.length_short). Show ();
stored in an external device SD card
Determine if sdcard exists and is readable or writable
if (Environment.getexternalstoragestate (). Equals (environment.media_mounted))
{
Fs.saveinsdcard (filename, filecontent);
Toast.maketext (Getapplicationcontext (), r.string.success, Toast.length_short). Show ();
}
Else
{
Toast.maketext (Getapplicationcontext (), R.string.failsdcard, Toast.length_short). Show ();
}
}
catch (Exception e)
{
Toast.maketext (Getapplicationcontext (), R.string.fail, Toast.length_short). Show ();
LOG.E (tag, e.getmessage ());
}
File name without path, input directly as Xy.txt
For SD card operations, you need to add permissions to the Androidmanifest.xml
Copy Code code as follows:
<!--permissions to create and delete files in SDcard-->
<uses-permission android:name= "Android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!--permissions to write data to SDcard-->
<uses-permission android:name= "Android.permission.WRITE_EXTERNAL_STORAGE"/>
three or one more APIs
①environment.getexternalstoragedirectory () Gets the path to the Mnt/sdcard directory, and for the android1.5,1.6 path is the SDcard directory
Two APIs are available in ②activity
Getcachedir () Gets the path to the data/data/application package name/cache directory
Getfilesdir () Gets the path to the data/data/application package name/files directory
