Android 4.4 后根据系统 Uri 查询 AbsoultePath

这里主要记录一次踩坑的经历。

大家都知道Android 4.4 前后根据Uri查询路径path，方式发生了变化，网上也是各种资料，方案可以说也很成熟。下面是在原有方案的基础上完善的。

import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.Environment;
import android.provider.DocumentsContract;
import android.provider.MediaStore;

public class FileUtilCompat {

    public static String getFilePathByUri(Context context, Uri uri) {
        String path = null;

        // 以 file:// 开头的
        if (ContentResolver.SCHEME_FILE.equals(uri.getScheme())) {
            path = uri.getPath();
            return path;
        }

        // 以 content:// 开头的，比如 content://media/extenral/images/media/17766
        if (ContentResolver.SCHEME_CONTENT.equals(uri.getScheme()) && Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
            return getDataColumn(context, uri, null, null);
        }
        // 4.4及之后的 是以 content:// 开头的，比如 content://com.android.providers.media.documents/document/image%3A235700
        if (ContentResolver.SCHEME_CONTENT.equals(uri.getScheme()) && Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            if (DocumentsContract.isDocumentUri(context, uri)) {
                if (isExternalStorageDocument(uri)) {
                    // ExternalStorageProvider
                    final String docId = DocumentsContract.getDocumentId(uri);
                    final String[] split = docId.split(":");
                    final String type = split[0];
                    if ("primary".equalsIgnoreCase(type)) {
                        path = Environment.getExternalStorageDirectory() + "/" + split[1];
                        return path;
                    }
                } else if (isDownloadsDocument(uri)) {
                    // DownloadsProvider
                    final String id = DocumentsContract.getDocumentId(uri); // 42行

                    final String[] split = id.split(":"); // 43行
                    final String type = split[0];
                    if ("raw".equalsIgnoreCase(type)) { //处理某些机型（比如Goole Pixel ）ID是raw:/storage/emulated/0/Download/c20f8664da05ab6b4644913048ea8c83.mp4
                        return split[1];
                    } // 49行

                    final Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"),
                            Long.valueOf(id));
                    path = getDataColumn(context, contentUri, null, null);
                    return path;
                } else if (isMediaDocument(uri)) {
                    // MediaProvider
                    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]};
                    path = getDataColumn(context, contentUri, selection, selectionArgs);
                    return path;
                }
            }
        }
        return null;
    }

    private static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {
        Cursor cursor = null;
        final String column = MediaStore.Images.Media.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;
    }

    private static boolean isExternalStorageDocument(Uri uri) {
        return "com.android.externalstorage.documents".equals(uri.getAuthority());
    }

    private static boolean isDownloadsDocument(Uri uri) {
        return "com.android.providers.downloads.documents".equals(uri.getAuthority());
    }

    private static boolean isMediaDocument(Uri uri) {
        return "com.android.providers.media.documents".equals(uri.getAuthority());
    }


}

今天偶然遇到一个很奇怪的事情，一个Android 9.0 手机，一个文件夹下的视频文件用我们的应用打不开了。这个文件位于download文件夹下。

经过调试发现，问题出在了 第42行，查询的I这个文件的ID是raw:/storage/emulated/0/Download/c20f8664da05ab6b4644913048ea8c83.mp4

很显然这个就是绝对路径并且多了个 raw: ，额 那个成熟的方案并没有处理DownloadsDocumen这种情况。

 // DownloadsProvider
  final String id = DocumentsContract.getDocumentId(uri);
  final String[] split = id.split(":");
  final String type = split[0];
  if ("raw".equalsIgnoreCase(type)) { //处理某些机型（比如Goole Pixel ）ID是raw:/storage/emulated/0/Download/c20f8664da05ab6b4644913048ea8c83.mp4
      return split[1];
  }

也就是完善后的方案中第 44行 — 第49行

参考资料：
https://github.com/luisfuertes/react-native-file-picker/issues/15
https://stackoverflow.com/questions/3401579/get-filename-and-path-from-uri-from-mediastore
https://github.com/Yalantis/uCrop/issues/386