Android学习笔记（四）--Android4.4中获取资源路径问题，改进文件选择器。
最近要做一个APP使用到文件选择，碰到4.4.2版本的手机就会出错，原来发现4.4获取资源路径已经改过了。
关于Android4.4的图片路径获取，如果回来的Uri的格式有两种：
Version 4.4.2 出现之前，Intent.ACTION_GET_CONTENT打开相册会返回如下形式的Uri :
content://media/external/images/media/3951 ，
使用ContentResolver查询MediaStore.Images.Media.DATA就可以找文件的URL, 然而在Google Nexus 7 上用同样的方法，却是返回如下Uri :
content://com.android.providers.media.documents/document/image:3951，
综合网上的方法，下面是经过测试可以正常使用的文件选择器。
1.首先 需要添加权限。
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
2.showFileChooser函数
private void showFileChooser(int file_code) { Intent intent = new Intent(Intent.ACTION_GET_CONTENT); // Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT); // Intent intent = new Intent(Intent.ACTION_PICK); intent.setType("image/*"); intent.addCategory(Intent.CATEGORY_OPENABLE); try { startActivityForResult( Intent.createChooser(intent, "Select a File to Upload"), file_code); } catch (android.content.ActivityNotFoundException ex) { Toast.makeText(getActivity(), "Please install a File Manager.", Toast.LENGTH_SHORT).show(); } }
3.返回结果处理（由于项目需要 case比较多，根据实际需求来增减）
public void onActivityResult(int requestCode, int resultCode, Intent data) { switch (requestCode) { case 0: if (resultCode == Activity.RESULT_OK) { Uri uri = data.getData(); String path = FileUtils.getPath(getActivity().getApplicationContext(), uri); mTextViewMain.setText(path); mainurl=new File(path); } break; case 1: if (resultCode == Activity.RESULT_OK) { // Get the Uri of the selected file Uri uri = data.getData(); String path = FileUtils.getPath(getActivity(), uri); mTextViewBody1.setText(path); body1=new File(path); } break; case 2: if (resultCode == Activity.RESULT_OK) { // Get the Uri of the selected file Uri uri = data.getData(); String path = FileUtils.getPath(getActivity(), uri); mTextViewBody2.setText(path); body2=new File(path); } break; case 3: if (resultCode == Activity.RESULT_OK) { // Get the Uri of the selected file Uri uri = data.getData(); String path = FileUtils.getPath(getActivity(), uri); mTextViewBody3.setText(path); body3=new File(path); } break; case 4: if (resultCode == Activity.RESULT_OK) { // Get the Uri of the selected file Uri uri = data.getData(); String path = FileUtils.getPath(getActivity(), uri); mTextViewBody4.setText(path); body4=new File(path); } break; } super.onActivityResult(requestCode, resultCode, data); }
4.FileUtils类（转载于：http://stackoverflow.com/questions/20067508/get-real-path-from-uri-android-kitkat-new-storage-access-framework）
public class FileUtils {/** * Get a file path from a Uri. This will get the the path for Storage Access * Framework Documents, as well as the _data field for the MediaStore and * other file-based ContentProviders. * * @param context The context. * @param uri The Uri to query. * @author paulburke */ public static String getPath(final Context context, final Uri uri) { final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT; // DocumentProvider if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) { // ExternalStorageProvider if (isExternalStorageDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final String type = split[0]; if ("primary".equalsIgnoreCase(type)) { return Environment.getExternalStorageDirectory() + "/" + split[1]; } // TODO handle non-primary volumes } // DownloadsProvider else if (isDownloadsDocument(uri)) { final String id = DocumentsContract.getDocumentId(uri); final Uri contentUri = ContentUris.withAppendedId( Uri.parse("content://downloads/public_downloads"), Long.valueOf(id)); return getDataColumn(context, contentUri, null, null); } // MediaProvider else if (isMediaDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final String type = split[0]; Uri contentUri = null; if ("image".equals(type)) { contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI; } else if ("video".equals(type)) { contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI; } else if ("audio".equals(type)) { contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; } final String selection = "_id=?"; final String[] selectionArgs = new String[] { split[1] }; return getDataColumn(context, contentUri, selection, selectionArgs); } } // MediaStore (and general) else if ("content".equalsIgnoreCase(uri.getScheme())) { return getDataColumn(context, uri, null, null); } // File else if ("file".equalsIgnoreCase(uri.getScheme())) { return uri.getPath(); } return null; } /** * Get the value of the data column for this Uri. This is useful for * MediaStore Uris, and other file-based ContentProviders. * * @param context The context. * @param uri The Uri to query. * @param selection (Optional) Filter used in the query. * @param selectionArgs (Optional) Selection arguments used in the query. * @return The value of the _data column, which is typically a file path. */ public static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) { Cursor cursor = null; final String column = "_data"; final String[] projection = { column }; try { cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null); if (cursor != null && cursor.moveToFirst()) { final int column_index = cursor.getColumnIndexOrThrow(column); return cursor.getString(column_index); } } finally { if (cursor != null) cursor.close(); } return null; } /** * @param uri The Uri to check. * @return Whether the Uri authority is ExternalStorageProvider. */ public static boolean isExternalStorageDocument(Uri uri) { return "com.android.externalstorage.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is DownloadsProvider. */ public static boolean isDownloadsDocument(Uri uri) { return "com.android.providers.downloads.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is MediaProvider. */ public static boolean isMediaDocument(Uri uri) { return "com.android.providers.media.documents".equals(uri.getAuthority()); }}
