android编程实现sd卡读取数据库的方法

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /><uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />

SQLiteDatabase db;private final String DATABASE_PATH = android.os.Environment .getExternalStorageDirectory().getAbsolutePath() + "/vote";private String DATABASE_FILENAME = "db_vote.db";// 初始化数据库private SQLiteDatabase openDatabase() {  try {   String databaseFilename = DATABASE_PATH + "/" + DATABASE_FILENAME;   File dir = new File(DATABASE_PATH);   if (!dir.exists())    dir.mkdir();   if (!(new File(databaseFilename)).exists()) {    InputStream is = getResources().openRawResource(R.raw.db_vote);    FileOutputStream fos = new FileOutputStream(databaseFilename);    byte[] buffer = new byte[8192];    int count = 0;    while ((count = is.read(buffer)) > 0) {     fos.write(buffer, 0, count);    }    fos.close();    is.close();   }   db = SQLiteDatabase.openOrCreateDatabase(databaseFilename, null);   return db;  } catch (Exception e) {   e.printStackTrace();  }  return null;}