Add task for importing/exporting

app/src/main/java/protect/card_locker/ImportExportTask.java

@@ -0,0 +1,146 @@
+package protect.card_locker;
+
+import android.app.Activity;
+import android.app.ProgressDialog;
+import android.content.DialogInterface;
+import android.os.AsyncTask;
+import android.os.Environment;
+import android.util.Log;
+import android.widget.Toast;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.nio.charset.Charset;
+
+class ImportExportTask extends AsyncTask<Void, Void, Void>
+{
+    private static final String TAG = "BudgetWatch";
+
+    private static final String TARGET_FILE = "LoyaltyCardLocker.csv";
+
+    private Activity activity;
+    private boolean doImport;
+    private DataFormat format;
+
+    private ProgressDialog progress;
+
+    public ImportExportTask(Activity activity, boolean doImport, DataFormat format)
+    {
+        super();
+        this.activity = activity;
+        this.doImport = doImport;
+        this.format = format;
+    }
+
+    private void toastWithArg(int stringId, String argument)
+    {
+        final String template = activity.getResources().getString(stringId);
+        final String message = String.format(template, argument);
+
+        activity.runOnUiThread(new Runnable()
+        {
+            @Override
+            public void run()
+            {
+                Toast.makeText(activity, message, Toast.LENGTH_LONG).show();
+            }
+        });
+    }
+
+    private void performImport(File importFile, DBHelper db)
+    {
+        if(importFile.exists() == false)
+        {
+            toastWithArg(R.string.fileMissing, importFile.getAbsolutePath());
+            return;
+        }
+
+        boolean result = false;
+
+        try
+        {
+            FileInputStream fileReader = new FileInputStream(importFile);
+            InputStreamReader reader = new InputStreamReader(fileReader, Charset.forName("UTF-8"));
+            result = MultiFormatImporter.importData(db, reader, format);
+            reader.close();
+        }
+        catch(IOException e)
+        {
+            Log.e(TAG, "Unable to import file", e);
+        }
+
+        int messageId = result ? R.string.importedFrom : R.string.importFailed;
+        toastWithArg(messageId, importFile.getAbsolutePath());
+    }
+
+    private void performExport(File exportFile, DBHelper db)
+    {
+        boolean result = false;
+
+        try
+        {
+            FileOutputStream fileWriter = new FileOutputStream(exportFile);
+            OutputStreamWriter writer = new OutputStreamWriter(fileWriter, Charset.forName("UTF-8"));
+            result = MultiFormatExporter.exportData(db, writer, format);
+            writer.close();
+        }
+        catch (IOException e)
+        {
+            Log.e(TAG, "Unable to export file", e);
+        }
+
+        int messageId = result ? R.string.exportedTo : R.string.exportFailed;
+        toastWithArg(messageId, exportFile.getAbsolutePath());
+    }
+
+    protected void onPreExecute()
+    {
+        progress = new ProgressDialog(activity);
+        progress.setTitle(doImport ? R.string.importing : R.string.exporting);
+
+        progress.setOnDismissListener(new DialogInterface.OnDismissListener()
+        {
+            @Override
+            public void onDismiss(DialogInterface dialog)
+            {
+                ImportExportTask.this.cancel(true);
+            }
+        });
+
+        progress.show();
+    }
+
+    protected Void doInBackground(Void... nothing)
+    {
+        final File sdcardDir = Environment.getExternalStorageDirectory();
+        final File importExportFile = new File(sdcardDir, TARGET_FILE);
+        final DBHelper db = new DBHelper(activity);
+
+        if(doImport)
+        {
+            performImport(importExportFile, db);
+        }
+        else
+        {
+            performExport(importExportFile, db);
+        }
+
+        return null;
+    }
+
+    protected void onPostExecute(Void result)
+    {
+        progress.dismiss();
+        Log.i(TAG, (doImport ? "Import" : "Export") + " Complete");
+    }
+
+    protected void onCancelled()
+    {
+        progress.dismiss();
+        Log.i(TAG, (doImport ? "Import" : "Export") + " Cancelled");
+    }
+}