在Android 4.4中将content:// URI转换为实际路径

Question

我尝试了下面的解决方案（参见下文）, 在Android 4.4中，调用startActivityForResult()会弹出一个名为“Open from”的活动页面，其中有“Recent”，“Images”和“Downloads”，还有多个应用程序可供选择。当我选择“Images”并尝试解析返回的内容URI时（使用下面的代码），调用cursor.getString()会返回null。如果我使用Gallery应用程序选择完全相同的文件，则cursor.getString()会返回文件路径。我只在API级别16和19中进行了测试。一切都按照期望工作在16中。至于19，我必须选择Gallery或其他应用程序，否则它不起作用。

private String getRealPathFromURI(Context context, Uri contentUri) {
    Cursor cursor = null;
    try { 
        String[] proj = { MediaStore.Images.Media.DATA };
        cursor = context.getContentResolver().query(contentUri,  proj, null, null, null);
        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        String path = cursor.getString(column_index);

        return path;
    } finally {
        if (cursor != null) {
            cursor.close();
        }
    }
}

- Raging Software

---

你找到解决方法了吗？ - Archie.bpgc

Answer 1

这将从MediaProvider、DownloadsProvider和ExternalStorageProvider获取文件路径，同时回退到您提到的非官方ContentProvider方法。

   /**
 * 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());
}

源代码 aFileChooser

- Kishan Vaghela

---

这个方法非常有效。需要补充的是，为了让我的上传代码（通过Retrofit）正常工作，我不得不在返回的字符串开头加上"file://"。 - PGMacDesign

@KishanVaghela getPath() 方法对于外部SD卡文件将返回null。有什么解决办法吗？ - KJEjava48

这个工具并不完美，会在Galaxy S7，Andorid N API24上导致java.lang.RuntimeException错误。当使用相机拍照时，错误是列“_data”不存在。 - Logan Guo

在 Oreo 中，对于位于“下载”文件夹中的文件抛出异常。 - abedfar

这段代码无法处理来自谷歌云端硬盘的文件和类型为"content://com.google.android.apps.docs.storage/document/acc%3D3%3Bdoc%3D1259"的Uri。 - Aayush Singla

Answer 2

将content:// URI转换为实际路径在Android 4.4上没有可靠的方法。一个content:// Uri不一定代表文件系统上的文件，更不用说你能访问的文件了。Android 4.4对存储框架的更改只是增加了你会遇到content:// Uri值的频率。如果你得到一个content:// Uri，请使用ContentResolver和openInputStream()，openOutputStream()等方法来使用它。

- CommonsWare

---

每当使用Intent.ACTION_GET_CONTENT来选择视频时，假设MediaStore提供程序将保存与返回的内容URI相关的信息是不正确的吗？ - woot

@TomReznik：使用ACTION_GET_CONTENT时，没有要求返回已经被MediaStore索引的Uri。 - CommonsWare

@CommonsWare 感谢您的回答，似乎每个人都在做发帖者所做的事情，即使从来没有保证它会一直起作用。我的问题是，如果我们需要一个文件而不是InputStream，那么这是否意味着我们必须将InputStream转换为文件？ - Richard Fung

@a_secret：首先，我建议您尝试找到其他解决方案来解决您正在尝试解决的问题，而不涉及“文件”（请参见去年我在此主题上的这篇文章）。否则，是的，您需要将“InputStream”的内容流式传输到自己的本地文件中。 - CommonsWare

非常糟糕，我们不能使用java.io.file！！我们必须更改旧代码。 - Ali Yousefi

Answer 3

我也遇到了这个问题，不过我的情况是想要指定一个具体的Uri到相册，以便之后可以使用裁剪。在KitKat的新文档浏览器中，除非您选择导航抽屉中的相册并像您所说的那样直接从那里打开图像或文件，否则我们似乎无法再这样做了。

在Uri的情况下，当从文档浏览器中打开时，仍然可以检索路径。

    Intent dataIntent= new Intent(Intent.ACTION_GET_CONTENT);
    dataIntent.setType("image/*"); //Or whatever type you need

然后在onActivityResult中：

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == ACTIVITY_SELECT_IMAGE && resultCode == RESULT_OK) {
        myUri = data.getData();
        String path = myUri.getPath();
        openPath(myUri);

    }
}

如果您需要使用该路径打开文件，则只需使用内容解析器：

public void openPath(Uri uri){
    InputStream is = null;
    try {
        is = getContentResolver().openInputStream(uri);
        //Convert your stream to data here
        is.close();

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

- Makerhack

---

这是我想要的解决方案。 - allsoft

Answer 4

这是在Google API中介绍的。您可以尝试以下操作：

private Bitmap getBitmapFromUri(Uri uri) throws IOException {
    ParcelFileDescriptor parcelFileDescriptor =
            getContentResolver().openFileDescriptor(uri, "r");
    FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
    Bitmap image = BitmapFactory.decodeFileDescriptor(fileDescriptor);
    parcelFileDescriptor.close();
    return image;
}

- FireBear

---

我需要文件的时候怎么办？ - CQM

开始出现 java.lang.SecurityException: Permission Denial: opening provider android.support.v4.content.FileProvider 异常。 - Shshank Bhong

最佳解决方案!! - Dario Brux

Answer 5

我用了一种不同的方法。stackoverflow上的每个答案都有某种问题，要么导致崩溃，要么无法解决。上面的第一个答案不能用于从whatsApp媒体中查找URI。

下面的解决方案是全能解决方案，对我有效。我在此处复制了完整的PathUtils类。使用getpath()函数获取路径。

public class PathUtils {

    private static final int BUFFER_SIZE = 1024 * 2;

    public static String getPath(Context context, Uri contentUri) {
        String fileName = getFileName(contentUri);
        if (!TextUtils.isEmpty(fileName)) {
            File copyFile = new File(context.getCacheDir()  + fileName+contentUri.getScheme());
            copy(context, contentUri, copyFile);
            return copyFile.getAbsolutePath();
        }
        return null;
    }

    public static String getFileName(Uri uri) {
        if (uri == null) return null;
        String fileName = null;
        String path = uri.getPath();
        int cut = path.lastIndexOf('/');
        if (cut != -1) {
            fileName = path.substring(cut + 1);
        }
        return fileName;
    }

    public static void copy(Context context, Uri srcUri, File dstFile) {
        try {
            InputStream inputStream = context.getContentResolver().openInputStream(srcUri);
            if (inputStream == null) return;
            OutputStream outputStream = new FileOutputStream(dstFile);
            copyMain(inputStream, outputStream);
            inputStream.close();
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    public static int copyMain(InputStream input, OutputStream output) throws Exception, IOException {
        byte[] buffer = new byte[BUFFER_SIZE];

        BufferedInputStream in = new BufferedInputStream(input, BUFFER_SIZE);
        BufferedOutputStream out = new BufferedOutputStream(output, BUFFER_SIZE);
        int count = 0, n = 0;
        try {
            while ((n = in.read(buffer, 0, BUFFER_SIZE)) != -1) {
                out.write(buffer, 0, n);
                count += n;
            }
            out.flush();
        } finally {
            try {
                out.close();
            } catch (IOException e) {
                Log.e(e.getMessage(), e.toString());
            }
            try {
                in.close();
            } catch (IOException e) {
                Log.e(e.getMessage(), e.toString());
            }
        }
        return count;
    }
}

- zimmy9537

Answer 6

如果你真的需要一个文件路径。首先，使用ContentResolver获取数据。然后，你可以将数据保存到临时文件中并使用该路径。

（我不得不在函数参数中使用带有File对象的库。）

- fatihpense

Answer 7

感谢@FireBear，我修改了答案，现在可以获取媒体文件的路径。

String filePath = saveBitmap(activity, getBitmapFromUri(imageUri), "tmpFile").getPath();

private Bitmap getBitmapFromUri(Context context, Uri uri) throws IOException {
        ParcelFileDescriptor parcelFileDescriptor =
                context.getContentResolver().openFileDescriptor(uri, "r");
        FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
        Bitmap image = BitmapFactory.decodeFileDescriptor(fileDescriptor);
        parcelFileDescriptor.close();
        return image;
    }

    private File saveBitmap(Context context, Bitmap bitmap, String name) {
        File filesDir = context.getFilesDir();
        File imageFile = new File(filesDir, name + ".jpg");
        OutputStream os;
        try {
            os = new FileOutputStream(imageFile);
            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, os);
            os.flush();
            os.close();
        } catch (Exception e) {
            //Log.e(getClass().getSimpleName(), "Error writing bitmap", e);
        }
        return imageFile;
    }

- Shshank Bhong

Answer 8

我知道这并没有直接回答问题本身，但就像@CommonsWare所说的那样，SAF并不是用来这种方式使用的。

也许一个解决方法是在应用程序的外部文件目录中创建文件的副本，使用它，然后删除它。

public File createFileCopy(Context context, DocumentFile file) {

        if (file == null || !file.exists() || file.getName() == null) {
            throw new IllegalArgumentException("The file must no be null, and must exist, and must have a name.");
        }

        File fileCopy = new File(context.getExternalFilesDir(null).getAbsolutePath(), file.getName());

        try {

            android.os.FileUtils.copy(openFileInputStream(file), new FileOutputStream(fileCopy));

            return fileCopy;

        } catch (Exception e) {
          // do whateveer you want with this exceeption
            e.printStackTrace();
        }
        return null;
    }

- Cícero Moura

Answer 9

这个函数将把内容URI转换为真实路径。

fun getRealPathFromUri(uri: Uri): String? {
val projection = arrayOf(MediaStore.Images.Media.DATA)
val cursor = contentResolver.query(uri, projection, null, null, null) ?: return null
val columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA)
cursor.moveToFirst()
val filePath = cursor.getString(columnIndex)
cursor.close()
return filePath }

Java中的相同代码

public String getRealPathFromUri(Uri uri) {
String[] projection = { MediaStore.Images.Media.DATA };
Cursor cursor = getContentResolver().query(uri, projection, null, null, null);
if (cursor == null) {
    return null;
}
int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
String filePath = cursor.getString(columnIndex);
cursor.close();
return filePath; }

- waleed

Answer 10

在Android中将content:// URI转换为实际路径。

我已经从一个SO答案中管理了这个fileUtils类，并从各种Uri获取了路径：

package com.alquran.tafhimul_quran.Common;


import android.annotation.SuppressLint;
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;
import android.util.Log;

import androidx.annotation.RequiresApi;

import java.io.File;

public class UtilsFile {




    private final static String PUBLIC_DOWNLOAD_PATH = "content://downloads/public_downloads";


    private final static String EXTERNAL_STORAGE_DOCUMENTS_PATH = "com.android.externalstorage.documents";


    private final static String DOWNLOAD_DOCUMENTS_PATH = "com.android.providers.downloads.documents";


    private final static String MEDIA_DOCUMENTS_PATH = "com.android.providers.media.documents";


    private final static String PHOTO_CONTENTS_PATH = "com.google.android.apps.photos.content";


    private Boolean isExternalStorageDocument(Uri uri) {
        return EXTERNAL_STORAGE_DOCUMENTS_PATH.equals(uri.getAuthority());

    }
    private Boolean isPublicDocument(Uri uri) {
        return PUBLIC_DOWNLOAD_PATH.equals(uri.getAuthority());

    }


    private Boolean isDownloadsDocument(Uri uri) {
        return DOWNLOAD_DOCUMENTS_PATH.equals(uri.getAuthority());

    }

    private Boolean isMediaDocument(Uri uri) {
        return MEDIA_DOCUMENTS_PATH.equals(uri.getAuthority());
    }


    private Boolean isGooglePhotosUri(Uri uri) {
        return MEDIA_DOCUMENTS_PATH.equals(uri.getAuthority());

    }
    private Boolean isPhotoContentUri(Uri uri) {
        return PHOTO_CONTENTS_PATH.equals(uri.getAuthority());

    }



    private String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {

        Cursor cursor = null;
        //String column = "_data" REMOVED IN FAVOR OF NULL FOR ALL
        //String projection = arrayOf(column) REMOVED IN FAVOR OF PROJECTION FOR ALL
        try {
            cursor = context.getContentResolver().query(uri, null, selection, selectionArgs, null);
            if (cursor != null && cursor.moveToFirst()) {
                int columnIndex = cursor.getColumnIndexOrThrow(DocumentsContract.Document.COLUMN_DISPLAY_NAME);
                return cursor.getString(columnIndex);
            }
        } catch (Exception e) {
            Log.e("PathUtils", "Error getting uri for cursor to read file: " + e.getMessage());
        } finally {
            assert cursor != null;
            cursor.close();
        }
        return null;

    }

    @RequiresApi(api = Build.VERSION_CODES.KITKAT)
    public  String getFullPathFromContentUri(final Context context, final Uri uri) {

        final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
        String filePath="";
        // 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];
                }//non-primary e.g sd card
                else {
                    if (Build.VERSION.SDK_INT > 20) {
                        //getExternalMediaDirs() added in API 21
                        File[] extenal = context.getExternalMediaDirs();
                        for (File f : extenal) {
                            filePath = f.getAbsolutePath();
                            if (filePath.contains(type)) {
                                int endIndex = filePath.indexOf("Android");
                                filePath = filePath.substring(0, endIndex) + split[1];
                            }
                        }
                    }else{
                        filePath = "/storage/" + type + "/" + split[1];
                    }
                    return filePath;
                }
            }
            // DownloadsProvider
            else if (isDownloadsDocument(uri)) {
                String fileName = getDataColumn(context,  uri,null, null);
                String uriToReturn = null;
                if (fileName != null) {
                    uriToReturn = Uri.withAppendedPath(
                            Uri.parse(
                                    Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath()), fileName
                    ).toString();
                }
                return uriToReturn;
            }
            // 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]
                };

                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;
            }

        }
        // 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();
        }
        else if (isPublicDocument(uri)){
            String id = DocumentsContract.getDocumentId(uri);
            final Uri contentUri = ContentUris.withAppendedId(
                    Uri.parse(PUBLIC_DOWNLOAD_PATH), Long.parseLong(id));
            String[] projection = {MediaStore.Images.Media.DATA};
            @SuppressLint("Recycle") Cursor cursor = context.getContentResolver().query(contentUri, projection, null, null, null);

            if (cursor != null && cursor.moveToFirst()) {
                int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
                cursor.moveToFirst();
                return cursor.getString(column_index);
            }
        }

        return null;
    }

}

OnActivityResult的使用方法：

if (requestCode == PICK_AUDIO_REQUEST && resultCode == RESULT_OK && data != null && data.getData() != null) {
            Uri uri = data.getData();

            UtilsFile utilsFile = new UtilsFile();
            String filePath = utilsFile.getFullPathFromContentUri(mContext, uri);
            System.out.println("Audio File Path : "+ filePath);

           // audioString = audioFileToString(filePath);

        }

- Noor Hossain