Android读写文件，适配Q以上
Android Q升级了文件系统，访问文件不仅仅是说动态权限了，有各种限制。权限什么的就不赘述了，下面介绍一下在10以上的系统中访问文件。
首先是打开文件管理器
/**
* 打开文件管理器 存储卡和外接U盘都可以访问
*/
public void openFileManager() {
Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("text/*");
startActivityForResult(intent, REQUEST_CODE_FILE);
}这个setType可以根据自己的需要，设置MIME类型，设置要访问什么类型的文件。具体MIME可以参考MIME类型-CSDN博客
然后会打开文件管理器，这里面可以访问手机存储的文件或者外插U盘内的文件，就根据自己需求选择文件就可以了。
选中的文件会在onActivityResult中返回
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK && requestCode == REQUEST_CODE_FILE){
//拿到需要解析的文件
Uri uri = data.getData();
String filePath= FileHelper.getFileAbsolutePath(this,uri);
if (!TextUtils.isEmpty(filePath)){
parseFile = new File(filePath);
binding.tvFileName.setText(parseFile.getName());
readFile();
}
}
}这里关键的一点就是把拿到的uri转换成filePath了，转换成路径之后就可以读文件，根据需求进行操作了。这个FileHelper转自Android打开系统文件管理器，并获取选中文件的路径，适配Android10及以上无法获取路径_intent.settype获取文件-CSDN博客
package com.......utils;
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.os.FileUtils;
import android.provider.DocumentsContract;
import android.provider.MediaStore;
import android.provider.OpenableColumns;
import androidx.annotation.RequiresApi;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* ================================================
* Description:通过uri获取本地文件的绝对路径
*
* ================================================
*/
public class FileHelper {
/**
* 根据Uri获取文件绝对路径，解决Android4.4以上版本Uri转换
*
* @param context
* @param imageUri
*/
public static String getFileAbsolutePath(Context context, Uri imageUri) {
if (context == null || imageUri == null) {
return null;
}
if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.KITKAT) {
return getRealFilePath(context, imageUri);
}
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT && android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.Q && DocumentsContract.isDocumentUri(context, imageUri)) {
if (isExternalStorageDocument(imageUri)) {
String docId = DocumentsContract.getDocumentId(imageUri);
String[] split = docId.split(":");
String type = split[0];
if ("primary".equalsIgnoreCase(type)) {
return Environment.getExternalStorageDirectory() + "/" + split[1];
}
} else if (isDownloadsDocument(imageUri)) {
String id = DocumentsContract.getDocumentId(imageUri);
Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));
return getDataColumn(context, contentUri, null, null);
} else if (isMediaDocument(imageUri)) {
String docId = DocumentsContract.getDocumentId(imageUri);
String[] split = docId.split(":");
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;
}
String selection = MediaStore.Images.Media._ID + "=?";
String[] selectionArgs = new String[]{split[1]};
return getDataColumn(context, contentUri, selection, selectionArgs);
}
} // MediaStore (and general)
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q){
return uriToFileApiQ(context,imageUri);
}
else if ("content".equalsIgnoreCase(imageUri.getScheme())) {
// Return the remote address
if (isGooglePhotosUri(imageUri)) {
return imageUri.getLastPathSegment();
}
return getDataColumn(context, imageUri, null, null);
}
// File
else if ("file".equalsIgnoreCase(imageUri.getScheme())) {
return imageUri.getPath();
}
return null;
}
//此方法 只能用于4.4以下的版本
private static String getRealFilePath(final Context context, final Uri uri) {
if (null == uri) {
return null;
}
final String scheme = uri.getScheme();
String data = null;
if (scheme == null) {
data = uri.getPath();
} else if (ContentResolver.SCHEME_FILE.equals(scheme)) {
data = uri.getPath();
} else if (ContentResolver.SCHEME_CONTENT.equals(scheme)) {
String[] projection = {MediaStore.Images.ImageColumns.DATA};
Cursor cursor = context.getContentResolver().query(uri, projection, null, null, null);
// Cursor cursor = context.getContentResolver().query(uri, new String[]{MediaStore.Images.ImageColumns.DATA}, null, null, null);
if (null != cursor) {
if (cursor.moveToFirst()) {
int index = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);
if (index > -1) {
data = cursor.getString(index);
}
}
cursor.close();
}
}
return data;
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is ExternalStorageProvider.
*/
private 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.
*/
private static boolean isDownloadsDocument(Uri uri) {
return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}
private static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {
Cursor cursor = null;
String column = MediaStore.Images.Media.DATA;
String[] projection = {column};
try {
cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);
if (cursor != null && cursor.moveToFirst()) {
int index = cursor.getColumnIndexOrThrow(column);
return cursor.getString(index);
}
} finally {
if (cursor != null) {
cursor.close();
}
}
return null;
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is MediaProvider.
*/
private static boolean isMediaDocument(Uri uri) {
return "com.android.providers.media.documents".equals(uri.getAuthority());
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is Google Photos.
*/
private static boolean isGooglePhotosUri(Uri uri) {
return "com.google.android.apps.photos.content".equals(uri.getAuthority());
}
/**
* Android 10 以上适配 另一种写法
* @param context
* @param uri
* @return
*/
public static String getFileFromContentUri(Context context, Uri uri) {
if (uri == null) {
return null;
}
String filePath;
String[] filePathColumn = {MediaStore.MediaColumns.DATA, MediaStore.MediaColumns.DISPLAY_NAME};
ContentResolver contentResolver = context.getContentResolver();
Cursor cursor = contentResolver.query(uri, filePathColumn, null,
null, null);
if (cursor != null) {
cursor.moveToFirst();
try {
filePath = cursor.getString(cursor.getColumnIndex(filePathColumn[0]));
return filePath;
} catch (Exception e) {
} finally {
cursor.close();
}
}
return "";
}
/**
* Android 10 以上适配
* @param context
* @param uri
* @return
*/
@RequiresApi(api = Build.VERSION_CODES.Q)
private static String uriToFileApiQ(Context context, Uri uri) {
File file = null;
//android10以上转换
if (uri.getScheme().equals(ContentResolver.SCHEME_FILE)) {
file = new File(uri.getPath());
} else if (uri.getScheme().equals(ContentResolver.SCHEME_CONTENT)) {
//把文件复制到沙盒目录
ContentResolver contentResolver = context.getContentResolver();
Cursor cursor = contentResolver.query(uri, null, null, null, null);
if (cursor.moveToFirst()) {
String displayName = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));
try {
InputStream is = contentResolver.openInputStream(uri);
File cache = new File(context.getExternalCacheDir().getAbsolutePath(), Math.round((Math.random() + 1) * 1000) + displayName);
FileOutputStream fos = new FileOutputStream(cache);
FileUtils.copy(is, fos);
file = cache;
fos.close();
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return file.getAbsolutePath();
}
}