k-9/src/com/fsck/k9/helper/FileBrowserHelper.java

package com.fsck.k9.helper;

import java.io.File;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.ActivityNotFoundException;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.Uri;
import android.text.InputType;
import android.widget.EditText;

import com.fsck.k9.K9;
import com.fsck.k9.R;

public class FileBrowserHelper {
    private static FileBrowserHelper sInstance;

    /**
     * callback class to provide the result of the fallback textedit path dialog
     */
    public interface FileBrowserFailOverCallback {
        /**
         * the user has entered a path
         * @param path the path as String
         */
        public void onPathEntered(String path);
        /**
         * the user has cancel the inputtext dialog
         */
        public void onCancel();
    }
    /**
     * factory method
     *
     */
    private FileBrowserHelper() {
    }
    public synchronized static FileBrowserHelper getInstance() {
        if (sInstance == null) {
            sInstance = new FileBrowserHelper();
        }
        return sInstance;
    }


    /**
     * tries to open known filebrowsers.
     * If no filebrowser is found and fallback textdialog is shown
     * @param c the context as activity
     * @param startPath: the default value, where the filebrowser will start.
     *      if startPath = null => the default path is used
     * @param requestcode: the int you will get as requestcode in onActivityResult
     *      (only used if there is a filebrowser installed)
     * @param callback: the callback (only used when no filebrowser is installed.
     *      if a filebrowser is installed => override the onActivtyResult Method
     *
     * @return true: if a filebrowser has been found (the result will be in the onActivityResult
     *          false: a fallback textinput has been shown. The Result will be sent with the callback method
     *
     *
     */
    public boolean showFileBrowserActivity(Activity c, File startPath, int requestcode, FileBrowserFailOverCallback callback) {
    	// A string array that specifies the name of the intent to use, and
    	// the scheme to use with it when setting the data for the intent.
        String[][] intentDetails = 
            { { "org.openintents.action.PICK_DIRECTORY", "file://" },  // OI File Manager (maybe others)
              { "com.androidworkz.action.PICK_DIRECTORY", "file://" }, // SystemExplorer
              { "com.estrongs.action.PICK_DIRECTORY", "file://" },     // ES File Explorer
              { Intent.ACTION_PICK, "folder://" } };                   // Blackmoon File Browser (maybe others)

        boolean success = false;

        if (startPath == null) {
            startPath = new File(K9.getAttachmentDefaultPath());
        }

        int listIndex = 0;
        do {
        	Intent intent = new Intent(intentDetails[listIndex][0]);
        	if (startPath != null) {
                intent.setData(Uri.parse(intentDetails[listIndex][1] + startPath.getPath()));
        	}
        	try {
                c.startActivityForResult(intent, requestcode);
                success = true;
            } catch (ActivityNotFoundException e) {
            	// Try the next intent in the list
            	listIndex++;
            };
        } while (!success && (listIndex < intentDetails.length));

        if (listIndex == intentDetails.length) {
            //No Filebrowser is installed => show a fallback textdialog
            showPathTextInput(c, startPath, callback);
            success = false;
        }

        return success;
    }

    private void showPathTextInput(final Activity c, final File startPath, final FileBrowserFailOverCallback callback) {
        AlertDialog.Builder alert = new AlertDialog.Builder(c);

        alert.setTitle(c.getString(R.string.attachment_save_title));
        alert.setMessage(c.getString(R.string.attachment_save_desc));
        final EditText input = new EditText(c);
        input.setInputType(InputType.TYPE_CLASS_TEXT);
        if (startPath != null)
            input.setText(startPath.toString());
        alert.setView(input);

        alert.setPositiveButton(c.getString(R.string.okay_action), new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
                String path = input.getText().toString();
                callback.onPathEntered(path);
            }
        });

        alert.setNegativeButton(c.getString(R.string.cancel_action),
        new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
                callback.onCancel();
            }
        });

        alert.show();
    }
}