Android for SDcard expansion card file Operation example detailed _android

Android's operation of SDcard expansion card files is a normal file operation, but there are still places to pay attention to. Like what:

1. Join SDcard Operation Authority ;

2. recognizes the existence of sdcard ;

3. You cannot create files directly in a sdcard root directory, but you need to create a directory first and then create a file ;

Examples are as follows:

(1) Add SDcard operation permission in Androidmanifest.xml

<!--sdcard permissions-->
<uses-permission android:name= "Android.permission.WRITE_EXTERNAL_STORAGE" ></ Uses-permission>

(2) Variable declaration:

Private final static String PATH = "/sdcard/digu";
Private final static String FILENAME = "/notes.txt";

(3) write files to SDcard:

/**
* Write file
/
private void Onwrite () {
   try {
     log.d (log_tag, "Start write");
     1. To determine whether there is a sdcard
     if (Environment.MEDIA_MOUNTED.equals (Environment
         . Getexternalstoragestate ())) {
       // Directory
       File Path = new file (path);
       File "
       f = new" (PATH + FILENAME);
       if (!path.exists ()) {
         //2. Create a directory, you can create path.mkdirs () when the application is started
         ();
       if (!f.exists ()) {
         //3. create file
         f.createnewfile ();
       }
       OutputStreamWriter OSW = new OutputStreamWriter (
           new FileOutputStream (f));
       4. Write the file and get the text value from EditView
       osw.write (Editor.gettext (). toString ());
       Osw.close ();
     }
   catch (Exception e) {
     log.d (log_tag, "file Create Error");
   }