转换文件:Uri文件在Android

编辑:对不起，我之前应该测试得更好。这应该可以工作:

new File(new URI(androidURI.toString()));

URI是java.net.URI。

你想要的是…

new File(uri.getPath());

．.． ,而不是……

new File(uri.toString());

笔记

1. 对于命名为uri并完全按照这个问题创建的android.net.Uri对象，uri.toString()返回格式为"file:///mnt/sdcard/myPicture.jpg"的String，而uri.getPath()返回格式为"/mnt/sdcard/myPicture.jpg"的String。
2. 我知道在Android系统中文件存储有一些细微差别。在这个回答中，我的意图是准确地回答提问者所问的问题，而不是深究其中的细微差别。

在寻找了很长一段时间后，这对我来说是有效的:

File file = new File(getPath(uri));




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

对于那些在这里寻找图像解决方案的人，特别是在这里。

private Bitmap getBitmapFromUri(Uri contentUri) {
String path = null;
String[] projection = { MediaStore.Images.Media.DATA };
Cursor cursor = getContentResolver().query(contentUri, projection, null, null, null);
if (cursor.moveToFirst()) {
int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
path = cursor.getString(columnIndex);
}
cursor.close();
Bitmap bitmap = BitmapFactory.decodeFile(path);
return bitmap;
}

这些对我都没用。我发现这是可行的解决方案。但我的情况仅限于图像。

String[] filePathColumn = { MediaStore.Images.Media.DATA };
Cursor cursor = getActivity().getContentResolver().query(uri, filePathColumn, null, null, null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
String filePath = cursor.getString(columnIndex);
cursor.close();

文件imageToUpload =新文件(新URI(androidURI.toString()));如果这是你在外部存储中创建的文件，则有效。

例如file:///storage/emulated/0/(一些目录和文件名)

我是这样做的:

try {
readImageInformation(new File(contentUri.getPath()));


} catch (IOException e) {
readImageInformation(new File(getRealPathFromURI(context,
contentUri)));
}


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

使用

InputStream inputStream = getContentResolver().openInputStream(uri);

直接复制文件。还看到:

https://developer.android.com/guide/topics/providers/document-provider.html

@CommonsWare解释得很好。我们真的应该采用他提出的解决方案。

正如你所看到的，有一个接口OpenableColumns，它只包含两个字段:DISPLAY_NAME和SIZE。

在我的例子中，我需要检索关于JPEG图像的EXIF信息，并在发送到服务器之前根据需要旋转它。为此，我使用ContentResolver和openInputStream()将一个文件内容复制到一个临时文件中

public String getRealPathFromURI(Uri Uri) {< / p >

    String result;
Cursor cursor = getContentResolver().query(uri, null, null, null, null);
if (cursor == null) {
result = uri.getPath();
cursor.close();
return result;
}
cursor.moveToFirst();
int idx = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);
result = cursor.getString(idx);
cursor.close();
return result;
}

然后使用从URI中获取文件:

        File finalFile = newFile(getRealPathFromURI(uri));

——希望能帮到你----

Android + Kotlin

1. 为Kotlin Android扩展添加依赖项:

   implementation 'androidx.core:core-ktx:{latestVersion}'

2. 从uri中获取文件:

   uri.toFile()

Android + Java

移到顶部即可;)

使用Kotlin甚至更容易:

val file = File(uri.path)

或者如果你正在使用Android的Kotlin扩展:

val file = uri.toFile()

谢谢你的评论

最好的解决方案

创建一个简单的FileUtil类用于创建、复制和重命名文件

我使用uri.toString()和uri.getPath()，但不为我工作。

import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.provider.OpenableColumns;
import android.util.Log;


import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;


public class FileUtil {
private static final int EOF = -1;
private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;


private FileUtil() {


}


public static File from(Context context, Uri uri) throws IOException {
InputStream inputStream = context.getContentResolver().openInputStream(uri);
String fileName = getFileName(context, uri);
String[] splitName = splitFileName(fileName);
File tempFile = File.createTempFile(splitName[0], splitName[1]);
tempFile = rename(tempFile, fileName);
tempFile.deleteOnExit();
FileOutputStream out = null;
try {
out = new FileOutputStream(tempFile);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
if (inputStream != null) {
copy(inputStream, out);
inputStream.close();
}


if (out != null) {
out.close();
}
return tempFile;
}


private static String[] splitFileName(String fileName) {
String name = fileName;
String extension = "";
int i = fileName.lastIndexOf(".");
if (i != -1) {
name = fileName.substring(0, i);
extension = fileName.substring(i);
}


return new String[]{name, extension};
}


private static String getFileName(Context context, Uri uri) {
String result = null;
if (uri.getScheme().equals("content")) {
Cursor cursor = context.getContentResolver().query(uri, null, null, null, null);
try {
if (cursor != null && cursor.moveToFirst()) {
result = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (cursor != null) {
cursor.close();
}
}
}
if (result == null) {
result = uri.getPath();
int cut = result.lastIndexOf(File.separator);
if (cut != -1) {
result = result.substring(cut + 1);
}
}
return result;
}


private static File rename(File file, String newName) {
File newFile = new File(file.getParent(), newName);
if (!newFile.equals(file)) {
if (newFile.exists() && newFile.delete()) {
Log.d("FileUtil", "Delete old " + newName + " file");
}
if (file.renameTo(newFile)) {
Log.d("FileUtil", "Rename file to " + newName);
}
}
return newFile;
}


private static long copy(InputStream input, OutputStream output) throws IOException {
long count = 0;
int n;
byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
while (EOF != (n = input.read(buffer))) {
output.write(buffer, 0, n);
count += n;
}
return count;
}
}

在代码中使用FileUtil类

try {
File file = FileUtil.from(MainActivity.this,fileUri);
Log.d("file", "File...:::: uti - "+file .getPath()+" file -" + file + " : " + file .exists());


} catch (IOException e) {
e.printStackTrace();
}

通过下面的代码，我能够获得adobe应用程序共享pdf文件作为流，并保存到android应用程序路径

Android.Net.Uri fileuri =
(Android.Net.Uri)Intent.GetParcelableExtra(Intent.ExtraStream);


fileuri i am getting as {content://com.adobe.reader.fileprovider/root_external/
data/data/com.adobe.reader/files/Downloads/sample.pdf}


string filePath = fileuri.Path;


filePath I am gettings as root_external/data/data/com.adobe.reader/files/Download/sample.pdf


using (var stream = ContentResolver.OpenInputStream(fileuri))
{
byte[] fileByteArray = ToByteArray(stream); //only once you can read bytes from stream second time onwards it has zero bytes


string fileDestinationPath ="<path of your destination> "
convertByteArrayToPDF(fileByteArray, fileDestinationPath);//here pdf copied to your destination path
}
public static byte[] ToByteArray(Stream stream)
{
var bytes = new List<byte>();


int b;
while ((b = stream.ReadByte()) != -1)
bytes.Add((byte)b);


return bytes.ToArray();
}


public static string convertByteArrayToPDF(byte[] pdfByteArray, string filePath)
{


try
{
Java.IO.File data = new Java.IO.File(filePath);
Java.IO.OutputStream outPut = new Java.IO.FileOutputStream(data);
outPut.Write(pdfByteArray);
return data.AbsolutePath;


}
catch (System.Exception ex)
{
return string.Empty;
}
}

扩展基于@Jacek kwiecieark回答转换图像uri到文件

fun Uri.toImageFile(context: Context): File? {
val filePathColumn = arrayOf(MediaStore.Images.Media.DATA)
val cursor = context.contentResolver.query(this, filePathColumn, null, null, null)
if (cursor != null) {
if (cursor.moveToFirst()) {
val columnIndex = cursor.getColumnIndex(filePathColumn[0])
val filePath = cursor.getString(columnIndex)
cursor.close()
return File(filePath)
}
cursor.close()
}
return null
}

如果我们使用File(uri.getPath())，它将不起作用

在这种情况下，特别是在Android上，使用字节的方式通常更快。

有了这个，我通过设置一个类FileHelper来解决这个问题，它被赋予了处理通过流从/向文件读取/写入字节的责任，以及一个类UriHelper，它被赋予了计算Uri路径和权限的责任。

据我们所知，string.getBytes((charset == null) ? DEFAULT_CHARSET:charset)可以帮助我们将你想要的字符串转换为你需要的字节。

如何让UriHelper和FileHelper你复制一个图片的Uri到一个文件，你可以运行:

FileHelper.getInstance().copy(UriHelper.getInstance().toFile(uri_of_a_picture)
, FileHelper.getInstance().createExternalFile(null, UriHelper.getInstance().generateFileNameBasedOnTimeStamp()
+ UriHelper.getInstance().getFileName(uri_of_a_picture, context), context)
);

关于我的UriHelper:

public class UriHelper {
private static UriHelper INSTANCE = new UriHelper();


public static UriHelper getInstance() {
return INSTANCE;
}


@SuppressLint("SimpleDateFormat")
public String generateFileNameBasedOnTimeStamp() {
return new SimpleDateFormat("yyyyMMdd_hhmmss").format(new Date()) + ".jpeg";
}


/**
* if uri.getScheme.equals("content"), open it with a content resolver.
* if the uri.Scheme.equals("file"), open it using normal file methods.
*/
//


public File toFile(Uri uri) {
if (uri == null) return null;
Logger.d(">>> uri path:" + uri.getPath());
Logger.d(">>> uri string:" + uri.toString());
return new File(uri.getPath());
}


public DocumentFile toDocumentFile(Uri uri) {
if (uri == null) return null;
Logger.d(">>> uri path:" + uri.getPath());
Logger.d(">>> uri string:" + uri.toString());
return DocumentFile.fromFile(new File(uri.getPath()));
}


public Uri toUri(File file) {
if (file == null) return null;
Logger.d(">>> file path:" + file.getAbsolutePath());
return Uri.fromFile(file); //returns an immutable URI reference representing the file
}


public String getPath(Uri uri, Context context) {
if (uri == null) return null;
if (uri.getScheme() == null) return null;
Logger.d(">>> uri path:" + uri.getPath());
Logger.d(">>> uri string:" + uri.toString());
String path;
if (uri.getScheme().equals("content")) {
//Cursor cursor = context.getContentResolver().query(uri, new String[] {MediaStore.Images.ImageColumns.DATA}, null, null, null);
Cursor cursor = context.getContentResolver().query(uri, null, null, null, null);
if (cursor == null) {
Logger.e("!!! cursor is null");
return null;
}
if (cursor.getCount() >= 0) {
Logger.d("... the numbers of rows:" + cursor.getCount()
+ "and the numbers of columns:" + cursor.getColumnCount());
if (cursor.isBeforeFirst()) {
while (cursor.moveToNext()) {
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i<cursor.getColumnCount(); i++) {
stringBuilder.append("... iterating cursor.getString(" + i +"(" + cursor.getColumnName(i) + ")):" + cursor.getString(i));
stringBuilder.append("\n");
}
Logger.d(stringBuilder.toString());
}
} else {
cursor.moveToFirst();
do {
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i<cursor.getColumnCount(); i++) {
stringBuilder.append("... iterating cursor.getString(" + i +"(" + cursor.getColumnName(i) + ")):" + cursor.getString(i));
stringBuilder.append("\n");
}
Logger.d(stringBuilder.toString());
} while (cursor.moveToNext());
}
path = uri.getPath();
cursor.close();
Logger.d("... content scheme:" + uri.getScheme() + "  and return:" + path);
return path;
} else {
path = uri.getPath();
Logger.d("... content scheme:" + uri.getScheme()
+ " but the numbers of rows in the cursor is < 0:" + cursor.getCount()
+ "  and return:" + path);
return path;
}
} else {
path = uri.getPath();
Logger.d("... not content scheme:" + uri.getScheme() + "  and return:" + path);
return path;
}
}


public String getFileName(Uri uri, Context context) {
if (uri == null) return null;
if (uri.getScheme() == null) return null;
Logger.d(">>> uri path:" + uri.getPath());
Logger.d(">>> uri string:" + uri.toString());
String path;
if (uri.getScheme().equals("content")) {
//Cursor cursor = context.getContentResolver().query(uri, new String[] {MediaStore.Images.ImageColumns.DATA}, null, null, null);
Cursor cursor = context.getContentResolver().query(uri, null, null, null, null);
if (cursor == null) {
Logger.e("!!! cursor is null");
return null;
}
if (cursor.getCount() >= 0) {
Logger.d("... the numbers of rows:" + cursor.getCount()
+ "and the numbers of columns:" + cursor.getColumnCount());
if (cursor.isBeforeFirst()) {
while (cursor.moveToNext()) {
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i<cursor.getColumnCount(); i++) {
stringBuilder.append("... iterating cursor.getString(" + i +"(" + cursor.getColumnName(i) + ")):" + cursor.getString(i));
stringBuilder.append("\n");
}
Logger.d(stringBuilder.toString());
}
} else {
cursor.moveToFirst();
do {
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i<cursor.getColumnCount(); i++) {
stringBuilder.append("... iterating cursor.getString(" + i +"(" + cursor.getColumnName(i) + ")):" + cursor.getString(i));
stringBuilder.append("\n");
}
Logger.d(stringBuilder.toString());
} while (cursor.moveToNext());
}
cursor.moveToFirst();
path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.ImageColumns.DISPLAY_NAME));
cursor.close();
Logger.d("... content scheme:" + uri.getScheme() + "  and return:" + path);
return path;
} else {
path = uri.getLastPathSegment();
Logger.d("... content scheme:" + uri.getScheme()
+ " but the numbers of rows in the cursor is < 0:" + cursor.getCount()
+ "  and return:" + path);
return path;
}
} else {
path = uri.getLastPathSegment();
Logger.d("... not content scheme:" + uri.getScheme() + "  and return:" + path);
return path;
}
}

｝

关于我的FileHelper:

public class FileHelper {
private static final String DEFAULT_DIR_NAME = "AmoFromTaiwan";
private static final int DEFAULT_BUFFER_SIZE = 1024;
private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
private static final int EOF = -1;
private static FileHelper INSTANCE = new FileHelper();


public static FileHelper getInstance() {
return INSTANCE;
}


private boolean isExternalStorageWritable(Context context) {
/*
String state = Environment.getExternalStorageState();
return Environment.MEDIA_MOUNTED.equals(state);
*/
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}


private boolean isExternalStorageReadable(Context context) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}


@SuppressLint("SimpleDateFormat")
private String generateFileNameBasedOnTimeStamp() {
return new SimpleDateFormat("yyyyMMdd_hhmmss").format(new Date()) + ".jpeg";
}


public File createExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
Logger.d("... going to access an external dir:" + dir_path);
dir = new File(dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! failed to mkdirs");
return null;
}
}
if (file_name == null) {
file_path = dir_path + File.separator + generateFileNameBasedOnTimeStamp();
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external dir:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}


public File createInternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
dir_path = dir.getAbsolutePath();
Logger.d("... going to access an internal dir:" + dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! mkdirs failed");
return null;
}
}
if (file_name == null) {
file = new File(dir, generateFileNameBasedOnTimeStamp());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}


public File getExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
if (file_name == null) {
file_path = dir_path;
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external file:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}


public File getInternalFile(String dir_name, String file_name, Context context) {
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
if (file_name == null) {
file = new File(dir.getAbsolutePath());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}


private byte[] readBytesFromFile(File file) {
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
long file_length;
byte[] buffer;
int offset = 0;
int next = 0;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
if (file.length() > Integer.MAX_VALUE) {
Logger.e("!!! file length is out of max of int");
return null;
} else {
file_length = file.length();
}
try {
fis = new FileInputStream(file);
//buffer = new byte[(int) file_length];
buffer = new byte[(int) file.length()];
long time_start = System.currentTimeMillis();
while (true) {
Logger.d("... now next:" + next + " and offset:" + offset);
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
next = fis.read(buffer, offset, (buffer.length-offset));
if (next < 0 || offset >= buffer.length) {
Logger.d("... completed to read");
break;
}
offset += next;
}
//if (offset < buffer.length) {
if (offset < (int) file_length) {
Logger.e("!!! not complete to read");
return null;
}
fis.close();
return buffer;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}


public byte[] readBytesFromFile(File file, boolean is_fis_fos_only) {
if (file == null) return null;
if (is_fis_fos_only) {
return readBytesFromFile(file);
}
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
BufferedInputStream bis;
ByteArrayOutputStream bos;
byte[] buf = new byte[(int) file.length()];
int num_read;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
try {
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
bos = new ByteArrayOutputStream();
long time_start = System.currentTimeMillis();
while (true) {
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
num_read = bis.read(buf, 0, buf.length); //1024 bytes per call
if (num_read < 0) break;
bos.write(buf, 0, num_read);
}
buf = bos.toByteArray();
fis.close();
bis.close();
bos.close();
return buf;
} catch (FileNotFoundException e) {
e.printStackTrace();
Logger.e("!!! FileNotFoundException");
return null;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}


/**
* streams (InputStream and OutputStream) transfer binary data
* if to write a string to a stream, must first convert it to bytes, or in other words encode it
*/
public boolean writeStringToFile(File file, String string, Charset charset) {
if (file == null) return false;
if (string == null) return false;
return writeBytesToFile(file, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset));
}


public boolean writeBytesToFile(File file, byte[] data) {
if (file == null) return false;
if (data == null) return false;
FileOutputStream fos;
BufferedOutputStream bos;
try {
fos = new FileOutputStream(file);
bos = new BufferedOutputStream(fos);
bos.write(data, 0, data.length);
bos.flush();
bos.close();
fos.close();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return false;
}
return true;
}


/**
* io blocks until some input/output is available.
*/
public boolean copy(File source, File destination) {
if (source == null || destination == null) return false;
Logger.d(">>> source:" + source.getAbsolutePath() + ", destination:" + destination.getAbsolutePath());
try {
FileInputStream fis = new FileInputStream(source);
FileOutputStream fos = new FileOutputStream(destination);
byte[] buffer = new byte[(int) source.length()];
int len;
while (EOF != (len = fis.read(buffer))) {
fos.write(buffer, 0, len);
}
if (true) { //debug
byte[] copies = readBytesFromFile(destination);
if (copies != null) {
int copy_len = copies.length;
Logger.d("... stream read and write done for " + copy_len + " bytes");
}
}
return destination.length() != 0;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}


public void list(final String path, final String end, final List<File> files) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
if (file.isDirectory()) {
for (File child : file.listFiles()){
list(child.getAbsolutePath(), end, files);
}
} else if (file.isFile()) {
if (end.equals("")) {
files.add(file);
} else {
if (file.getName().endsWith(end)) files.add(file);
}
}
}


public String[] splitFileName(File file, String split) {
String path;
String ext;
int lastIndexOfSplit = file.getAbsolutePath().lastIndexOf(split);
if (lastIndexOfSplit < 0) {
path = file.getAbsolutePath();
ext = "";
} else {
path = file.getAbsolutePath().substring(0, lastIndexOfSplit);
ext = file.getAbsolutePath().substring(lastIndexOfSplit);
}
return new String[] {path, ext};
}


public File rename(File old_file, String new_name) {
if (old_file == null || new_name == null) return null;
Logger.d(">>> old file path:" + old_file.getAbsolutePath() + ", new file name:" + new_name);
File new_file = new File(old_file, new_name);
if (!old_file.equals(new_file)) {
if (new_file.exists()) { //if find out previous file/dir at new path name exists
if (new_file.delete()) {
Logger.d("... succeeded to delete previous file at new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to delete previous file at new abstract path name");
return null;
}
}
if (old_file.renameTo(new_file)) {
Logger.d("... succeeded to rename old file to new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to rename old file to new abstract path name");
}
} else {
Logger.d("... new and old file have the equal abstract path name:" + new_file.getAbsolutePath());
}
return new_file;
}


public boolean remove(final String path, final String end) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
boolean result = false;
if (file.isDirectory()) {
for (File child : file.listFiles()){
result = remove(child.getAbsolutePath(), end);
}
} else if (file.isFile()) {
if (end.equals("")) {
result = file.delete();
} else {
if (file.getName().endsWith(end)) result = file.delete();
}
} else {
Logger.e("!!! child is not file or directory");
}
return result;
}


@TargetApi(Build.VERSION_CODES.O)
public byte[] readNIOBytesFromFile(String path) throws IOException {
Logger.d(">>> path:" + path);
if (!Files.exists(Paths.get(path), LinkOption.NOFOLLOW_LINKS)) {
Logger.e("!!! file doesn't exists");
return null;
} else {
return Files.readAllBytes(Paths.get(path));
}
}


@TargetApi(Build.VERSION_CODES.O)
public File writeNIOBytesToFile(String dir, String name, byte[] data) {
Logger.d(">>> dir:" + dir + ", name:" + name);
Path path_dir;
Path path_file;
try {
if (!Files.exists(Paths.get(dir), LinkOption.NOFOLLOW_LINKS)) {
Logger.d("... make a dir");
path_dir = Files.createDirectories(Paths.get(dir));
if (path_dir == null) {
Logger.e("!!! failed to make a dir");
return null;
}
}
path_file = Files.write(Paths.get(name), data);
return path_file.toFile();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}


@TargetApi(Build.VERSION_CODES.O)
public void listNIO(final String dir, final String end, final List<File> files) throws IOException {
Logger.d(">>> dir:" + dir + ", end:" + end);
Files.walkFileTree(Paths.get(dir), new FileVisitor<Path>() {
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}


@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}


@Override
public FileVisitResult visitFileFailed(Path file, IOException exc) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}


@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
});
}


/**
* recursion
*/
private int factorial (int x) {
if (x > 1) return (x*(factorial(x-1)));
else if (x == 1) return x;
else return 0;
}

｝

添加onActivityResult，获取docx或pdf文件

var imageUriPath = ""
imageUriPath =
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val split = (imageUri.path ? : "").split(":") //split the path.
split[1]
} else {
imageUri.path ? : ""
}
val file = File(imageUriPath)

如果你有一个符合DocumentContract的Uri，那么你可能不想使用File。 如果你在kotlin上，使用DocumentFile来做你在旧世界中使用File来做的事情，并使用ContentResolver来获取流。< / p >

其他的东西几乎都肯定会坏。

使用内容解析器获取输入流

InputStream inputStream = getContentResolver().openInputStream(uri);

然后将输入流复制到文件中

FileUtils.copyInputStreamToFile(inputStream, file);

样品使用方法:

private File toFile(Uri uri) throws IOException {
String displayName = "";
Cursor cursor = getContentResolver().query(uri, null, null, null, null);


if(cursor != null && cursor.moveToFirst()){
try {
displayName = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));
}finally {
cursor.close();
}
}


File file =  File.createTempFile(
FilenameUtils.getBaseName(displayName),
"."+FilenameUtils.getExtension(displayName)
);
InputStream inputStream = getContentResolver().openInputStream(uri);
FileUtils.copyInputStreamToFile(inputStream, file);
return file;
}

uri.toString()给我:"content://com.google.android.apps.nbu.files.provider/1/file%3A%2F%2F%2Fstorage%2Femulated%2F0%2FDownload%2Fbackup.file"

uri.getPath()给我:"/1/file:///storage/emulated/0/Download/backup.file"

new File(uri.getPath())给我"/1/file:/storage/emulated/0/Download/backup.file"

因此，如果你有一个文件的访问权限，并希望避免使用ContentResolver或直接读取文件，答案是:

private String uriToPath( Uri uri )
{
File backupFile = new File( uri.getPath() );
String absolutePath = backupFile.getAbsolutePath();
return absolutePath.substring( absolutePath.indexOf( ':' ) + 1 );
}

为简化回答，跳过错误处理

你可以使用这个函数从uri中获取文件在新的android和旧的

fun getFileFromUri(context: Context, uri: Uri?): File? {
uri ?: return null
uri.path ?: return null


var newUriString = uri.toString()
newUriString = newUriString.replace(
"content://com.android.providers.downloads.documents/",
"content://com.android.providers.media.documents/"
)
newUriString = newUriString.replace(
"/msf%3A", "/image%3A"
)
val newUri = Uri.parse(newUriString)


var realPath = String()
val databaseUri: Uri
val selection: String?
val selectionArgs: Array<String>?
if (newUri.path?.contains("/document/image:") == true) {
databaseUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI
selection = "_id=?"
selectionArgs = arrayOf(DocumentsContract.getDocumentId(newUri).split(":")[1])
} else {
databaseUri = newUri
selection = null
selectionArgs = null
}
try {
val column = "_data"
val projection = arrayOf(column)
val cursor = context.contentResolver.query(
databaseUri,
projection,
selection,
selectionArgs,
null
)
cursor?.let {
if (it.moveToFirst()) {
val columnIndex = cursor.getColumnIndexOrThrow(column)
realPath = cursor.getString(columnIndex)
}
cursor.close()
}
} catch (e: Exception) {
Log.i("GetFileUri Exception:", e.message ?: "")
}
val path = realPath.ifEmpty {
when {
newUri.path?.contains("/document/raw:") == true -> newUri.path?.replace(
"/document/raw:",
""
)
newUri.path?.contains("/document/primary:") == true -> newUri.path?.replace(
"/document/primary:",
"/storage/emulated/0/"
)
else -> return null
}
}
return if (path.isNullOrEmpty()) null else File(path)
}

另一种实现方法是创建临时文件。做那件事:

fun createTmpFileFromUri(context: Context, uri: Uri, fileName: String): File? {
return try {
val stream = context.contentResolver.openInputStream(uri)
val file = File.createTempFile(fileName, "", context.cacheDir)
org.apache.commons.io.FileUtils.copyInputStreamToFile(stream,file)
file
} catch (e: Exception) {
e.printStackTrace()
null
}
}

我们使用Apache Commons库FileUtils类。将它添加到您的项目:

implementation "commons-io:commons-io:2.7"

获取文件正确使用上下文uri， 感谢@Mohsents， @Bogdan Kornev， @CommonsWare， @Juan Camilo Rodriguez的回答Durán;

我从uri中创建了一个inputStream，并使用这个iStream创建了一个临时文件，最后我能够从这个文件中提取uri和路径。

fun createFileFromContentUri(fileUri : Uri) : File{


var fileName : String = ""


fileUri.let { returnUri ->
requireActivity().contentResolver.query(returnUri,null,null,null)
}?.use { cursor ->
val nameIndex = cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME)
cursor.moveToFirst()
fileName = cursor.getString(nameIndex)
}
    

//  For extract file mimeType
val fileType: String? = fileUri.let { returnUri ->
requireActivity().contentResolver.getType(returnUri)
}


val iStream : InputStream = requireActivity().contentResolver.openInputStream(fileUri)!!
val outputDir : File = context?.cacheDir!!
val outputFile : File = File(outputDir,fileName)
copyStreamToFile(iStream, outputFile)
iStream.close()
return  outputFile
}


fun copyStreamToFile(inputStream: InputStream, outputFile: File) {
inputStream.use { input ->
val outputStream = FileOutputStream(outputFile)
outputStream.use { output ->
val buffer = ByteArray(4 * 1024) // buffer size
while (true) {
val byteCount = input.read(buffer)
if (byteCount < 0) break
output.write(buffer, 0, byteCount)
}
output.flush()
}
}
}

使用这个来写入文件，它为我工作时，gif的uri是由GBoard提供的，我必须在我的应用程序数据复制该gif。

    try {
String destinationFilePath = getExternalFilesDir("gifs") + "/tempFile.txt";
InputStream inputStream = getContentResolver().openInputStream(uri);
OutputStream outputStream = new FileOutputStream(destinationFilePath);


byte[] buffer = new byte[1024];
int bytesRead;


while ((bytesRead = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}


inputStream.close();
outputStream.close();
}
catch (Exception e) {
e.printStackTrace();
}