Android development-operations on files on the SD card are carried from the Network)

1. Get the directory of the storage device:/sdcard (generally)

Sdpath = environment. getexternalstoragedirectory () + "/";


2. Determine whether the folder on the SD card exists: Use the exists () method of the file object.


/**

* Determine whether a file already exists;

*

/

Public Boolean checkfileexists (string filepath ){

File file = new file (sdpath + filepath );

Return file. exists ();

}


3. Create a directory on the SD card: Use the mkdir () method of the file object.


/*

* Create a directory on the SD card;

*/

Public file createdir (string dirpath ){

File dir = new file (sdpath + dirpath );

Dir. mkdir ();

Return dir;

}


4. Create a file on the SD card: Use the createnewfile () method of the file object.

/*

* Create a file on the SD card;

*/

Public file createfile (string filepath) throws ioexception {

File file = new file (sdpath + filepath );

File. createnewfile ();

Return file;

}

5. Write the inputstream byte stream to the SD card file.

/**

* Write data from an inputstream to the SD card.

*/

Public file writestreamtosdcard (string dirpath, string filename, inputstream input ){

File file = NULL;

Outputstream output = NULL;

Try {

// Create a directory;

Createdir (dirpath );

// Create a file in the Created directory;

File = createfile (dirpath + filename );

Output = new fileoutputstream (File );

Byte [] bt = new byte [4*1024];

While (input. Read (BT )! =-1 ){

Output. Write (BT );

}

// Refresh the cache,

Output. Flush ();

} Catch (ioexception e ){

E. printstacktrace ();

}

Finally {


Try {

Output. Close ();

}

Catch (exception e ){

E. printstacktrace ();

}

}


Return file;


}

6. Access Permissions:

Add the following to androidmanifest:

<Uses-Permission Android: Name = "android. Permission. Internet"> </uses-Permission>

<Uses-Permission Android: Name = "android. Permission. write_external_storage"> </uses-Permission>