在Android上将数据库备份到SDCard
我正在使用下面的代码写一个备份到SDCard，我得到
java.io.IOException: Parent directory of file is not writable: /sdcard/mydbfile.db
private class ExportDatabaseFileTask extends AsyncTask<String, Void, Boolean> { private final ProgressDialog dialog = new ProgressDialog(ctx); // can use UI thread here protected void onPreExecute() { this.dialog.setMessage("Exporting database..."); this.dialog.show(); } // automatically done on worker thread (separate from UI thread) protected Boolean doInBackground(final String... args) { File dbFile = new File(Environment.getDataDirectory() + "/data/com.mypkg/databases/mydbfile.db"); File exportDir = new File(Environment.getExternalStorageDirectory(), ""); if (!exportDir.exists()) { exportDir.mkdirs(); } File file = new File(exportDir, dbFile.getName()); try { file.createNewFile(); this.copyFile(dbFile, file); return true; } catch (IOException e) { Log.e("mypck", e.getMessage(), e); return false; } } // can use UI thread here protected void onPostExecute(final Boolean success) { if (this.dialog.isShowing()) { this.dialog.dismiss(); } if (success) { Toast.makeText(ctx, "Export successful!", Toast.LENGTH_SHORT).show(); } else { Toast.makeText(ctx, "Export failed", Toast.LENGTH_SHORT).show(); } } void copyFile(File src, File dst) throws IOException { FileChannel inChannel = new FileInputStream(src).getChannel(); FileChannel outChannel = new FileOutputStream(dst).getChannel(); try { inChannel.transferTo(0, inChannel.size(), outChannel); } finally { if (inChannel != null) inChannel.close(); if (outChannel != null) outChannel.close(); } } }
你有清单中定义的权限吗？
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
