Android Studio中的错误，下载文件夹中有文件选择器

Question

我的问题

我目前正在使用安卓工作室开发一个安卓应用程序。要选择一个文件，用户单击一个按钮，资源管理器打开，他可以选择文件。在这个过程中，我使用了一个名为FileChooser.Java的助手类。只要用户不从下载文件夹中选择文件，整个系统就可以很好地运行。

如果用户试图从下载文件夹中选择一个文件，就会发生这种情况：

NumberFormatException：对于输入字符串："msf:80123">

FileChooser返回的URL：content://com.android.providers.downloads.documents/document/msf:80662

这是因为helper类需要一个长类型。删除msf:并将ID添加到末尾也不起作用。安卓似乎在下载文件夹中的所有内容中都添加了msf:标记。

我正在寻找一个有效的解决方案，从下载文件夹调用文件。

呼叫

Uri selectedFile = data.getData();
InputStream dataStream = new FileInputStream(FileChooser.getPath(getContext(), selectedFile));

FileChooser类中的异常调用

final Uri contentUri = ContentUris.withAppendedId(
Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

帮助程序类文件选择器

package com.example.dsvconverter.helper;
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 FileChooser {
/**
* 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 String[] split = id.split(":");
final String type = split[0];
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());
}
}

更新：@blackapps提供的代码有效，但现在我遇到了一个新问题。

黑应用程序代码：

InputStream dataStream = getContentResolver().openInputStream(data.getData());

这个解决方案是有效的，但是现在有些不同了。我正在制作PGP工具，此InputStream包含从所选文件读取的公钥。如果我用您的方式创建InputStream，PGP库将不再将其识别为公钥。但是，如果我将它打印到控制台中，它看起来是正确的和相同的。

问题：

为什么@Blackapps解决方案有效，但库不再将其识别为公钥，即使打印的字符串是1:1相同的？

Answer 1

唯一的问题是获取下载目录的路径或msf和NumberFormat异常，试试这个。它对我来说是正确的

package com.example.bookingmelbourne;
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.provider.OpenableColumns;
import android.text.TextUtils;
import android.util.Log;
import androidx.annotation.Nullable;
import androidx.annotation.WorkerThread;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class FileUtils {
private static final String TAG = "FileUtils";
@WorkerThread
@Nullable
public static String getReadablePathFromUri(Context context, Uri uri) {
String path = null;
if ("file".equalsIgnoreCase(uri.getScheme())) {
path = uri.getPath();
}
if (Build.VERSION.SDK_INT > Build.VERSION_CODES.KITKAT) {
path = getPath(context, uri);
}
if (TextUtils.isEmpty(path)) {
return path;
}
Log.d(TAG, "get path from uri: " + path);
if (!isReadablePath(path)) {
int index = path.lastIndexOf("/");
String name = path.substring(index + 1);
String dstPath = context.getCacheDir().getAbsolutePath() + File.separator + name;
if (copyFile(context, uri, dstPath)) {
path = dstPath;
Log.d(TAG, "copy file success: " + path);
} else {
Log.d(TAG, "copy file fail!");
} 
}
return path;
}
public static String getPath(final Context context, final Uri uri) {
final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
if (isExternalStorageDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
Log.d("External Storage", docId);
final String[] split = docId.split(":");
final String type = split[0];
if ("primary".equalsIgnoreCase(type)) {
return Environment.getExternalStorageDirectory() + "/" + split[1];
}
} else if (isDownloadsDocument(uri)) {
String dstPath = context.getCacheDir().getAbsolutePath() + File.separator + getFileName(context,uri);
if (copyFile(context, uri, dstPath)) {
Log.d(TAG, "copy file success: " + dstPath);
return dstPath;
} else {
Log.d(TAG, "copy file fail!");
}

} 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);
}
} else if ("content".equalsIgnoreCase(uri.getScheme())) {
return getDataColumn(context, uri, null, null);
} else if ("file".equalsIgnoreCase(uri.getScheme())) {
return uri.getPath();
}
return null;
}
public static String getFileName(Context context, Uri uri) {
Cursor cursor = context.getContentResolver().query(uri,null,null,null,null);
int nameindex = cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
cursor.moveToFirst();
return  cursor.getString(nameindex);
}

private 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;
}
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());
}
private static boolean isReadablePath(@Nullable String path) {
if (TextUtils.isEmpty(path)) {
return false;
}
boolean isLocalPath;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
if (!TextUtils.isEmpty(path)) {
File localFile = new File(path);
isLocalPath = localFile.exists() && localFile.canRead();
} else {
isLocalPath = false;
}
} else {
isLocalPath = path.startsWith(File.separator);
}
return isLocalPath;
}
private static boolean copyFile(Context context, Uri uri, String dstPath) {
InputStream inputStream = null;
OutputStream outputStream = null;
try {
inputStream = context.getContentResolver().openInputStream(uri);
outputStream = new FileOutputStream(dstPath);
byte[] buff = new byte[100 * 1024];
int len;
while ((len = inputStream.read(buff)) != -1) {
outputStream.write(buff, 0, len);
}
} catch (Exception e) {
e.printStackTrace();
return false;
} finally {
if (inputStream != null) {
try {
inputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (outputStream != null) {
try {
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
return true;
}
}

之后，您可以调用这个传递上下文和uri对象的方法

String realPath = FileUtils.getReadablePathFromUri(context,uri)

Answer 2

In onActivityResult((：

InputStream dataStream = getContentResolver().openInputStream(data.getData());

放弃getPath((函数。

这适用于所有世纪。