我在将该 pdf 文件复制到缓存目录后解决了问题
请在此处查看完整的解决方案：
public static final String DOCUMENTS_DIR = "documents";
if (isDownloadsDocument(uri)) {
final String id = DocumentsContract.getDocumentId(uri);
if (id != null && id.startsWith("raw:")) {
return id.substring(4);
}
String[] contentUriPrefixesToTry = new String[]{
"content://downloads/public_downloads",
"content://downloads/my_downloads"
};
for (String contentUriPrefix : contentUriPrefixesToTry) {
Uri contentUri = ContentUris.withAppendedId(Uri.parse(contentUriPrefix), Long.valueOf(id));
try {
String path = getDataColumn(context, contentUri, null, null);
if (path != null) {
return path;
}
} catch (Exception e) {}
}
// path could not be retrieved using ContentResolver, therefore copy file to accessible cache using streams
String fileName = getFileName(context, uri);
File cacheDir = getDocumentCacheDir(context);
File file = generateFileName(fileName, cacheDir);
String destinationPath = null;
if (file != null) {
destinationPath = file.getAbsolutePath();
saveFileFromUri(context, uri, destinationPath);
}
return destinationPath;
}
public static String getFileName(@NonNull Context context, Uri uri) {
String mimeType = context.getContentResolver().getType(uri);
String filename = null;
if (mimeType == null && context != null) {
String path = getPath(context, uri);
if (path == null) {
filename = getName(uri.toString());
} else {
File file = new File(path);
filename = file.getName();
}
} else {
Cursor returnCursor = context.getContentResolver().query(uri, null, null, null, null);
if (returnCursor != null) {
int nameIndex = returnCursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
returnCursor.moveToFirst();
filename = returnCursor.getString(nameIndex);
returnCursor.close();
}
}
return filename;
}
public static String getName(String filename) {
if (filename == null) {
return null;
}
int index = filename.lastIndexOf('/');
return filename.substring(index + 1);
}
public static File getDocumentCacheDir(@NonNull Context context) {
File dir = new File(context.getCacheDir(), DOCUMENTS_DIR);
if (!dir.exists()) {
dir.mkdirs();
}
// logDir(context.getCacheDir());
// logDir(dir);
return dir;
}
@Nullable
public static File generateFileName(@Nullable String name, File directory) {
if (name == null) {
return null;
}
File file = new File(directory, name);
if (file.exists()) {
String fileName = name;
String extension = "";
int dotIndex = name.lastIndexOf('.');
if (dotIndex > 0) {
fileName = name.substring(0, dotIndex);
extension = name.substring(dotIndex);
}
int index = 0;
while (file.exists()) {
index++;
name = fileName + '(' + index + ')' + extension;
file = new File(directory, name);
}
}
try {
if (!file.createNewFile()) {
return null;
}
} catch (IOException e) {
//Log.w(TAG, e);
return null;
}
//logDir(directory);
return file;
}
private static void saveFileFromUri(Context context, Uri uri, String destinationPath) {
InputStream is = null;
BufferedOutputStream bos = null;
try {
is = context.getContentResolver().openInputStream(uri);
bos = new BufferedOutputStream(new FileOutputStream(destinationPath, false));
byte[] buf = new byte[1024];
is.read(buf);
do {
bos.write(buf);
} while (is.read(buf) != -1);
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (is != null) is.close();
if (bos != null) bos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
感谢对此thread的帮助