如何将非媒体文件从 /storage/emulated/0/Download 移动到 getExternalFilesDir()

Question

我创建了一个能够下载非媒体文件的应用程序。 现在我计划扩展应用程序以移动下载的文件(filetype=map) 。 我正在使用compileSdkVersion 29和targetSdkVersion 29 。 这个https://developer.android.com/training/data-storage说我必须使用“存储访问框架”。 我使用了从这里截取的“ 如何在 android 10 上列出所有 pdf 文件？ ”但它仅适用于媒体文件（uri 到文件）。 有人知道在哪里可以找到工作剪断吗？

Answer 1

为了复制像“whatever.map”这样的文件，必须在以下代码中进行哪些更改？ 问题的重要部分是文件类型“map”，这意味着它是非媒体文件，mime 类型未知。 目标 sdk必须是29 。 当我 - 使用以下代码 - 选择像“whatever.png”这样的文件时，它可以工作。 但是在复制到 /storage/emulated/0/Download 之前将文件“whatever.map”重命名为“whatever.png”对于目标 sdk 29也是不可能的。

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/open_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="104dp"
        android:layout_marginTop="144dp"
        android:onClick="openFile"

        android:text="Select"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/save_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="188dp"
        android:layout_marginTop="280dp"
        android:onClick="saveFile"
        android:text="Copy"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="1.0"
        app:layout_constraintStart_toEndOf="@+id/open_button"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

package org.hagerti.storagedemo;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.app.Activity;
import android.content.Intent;
import android.icu.text.SimpleDateFormat;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.channels.FileChannel;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

    final static String className = MainActivity.class.getSimpleName();
    private static final int CREATE_REQUEST_CODE = 40;
    private static final int OPEN_REQUEST_CODE = 41;
    private static final int SAVE_REQUEST_CODE = 42;
    final private static String myMimeType = "image/png";
    //final private static String myMimeType = "text/map";

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Uri currentUri = null;
        if (resultCode == Activity.RESULT_OK) {
            if (requestCode == SAVE_REQUEST_CODE) {
                if (data != null) {
                    currentUri = data.getData();
                    writeFileContent(currentUri);
                }
            } else if (requestCode == OPEN_REQUEST_CODE) {

                if (data != null) {
                    currentUri = data.getData();

                    try {
                        String content = readFileContent(currentUri);
                    } catch (IOException e) {
                    }
                }
            }

        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }

    public void openFile(View view) {
        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        intent.setType(myMimeType);
        startActivityForResult(intent, OPEN_REQUEST_CODE);
        /**
         * http://www.iana.org/assignments/media-types/media-types.xhtml
         * Often used media types:
         * image/jpeg
         * audio/mpeg4-generic
         * text/html
         * audio/mpeg
         * audio/aac
         * audio/wav
         * audio/ogg
         * audio/midi
         * audio/x-ms-wma
         * video/mp4
         * video/x-msvideo
         * video/x-ms-wmv
         * image/png
         * image/jpeg
         * image/gif
         * .xml ->text/xml
         * .txt -> text/plain
         * .cfg -> text/plain
         * .csv -> text/plain
         * .conf -> text/plain
         * .rc -> text/plain
         * .htm -> text/html
         * .html -> text/html
         * .pdf -> application/pdf
         * .apk -> application/vnd.android.package-archive
         */
    }

    private String readFileContent(Uri uri) throws IOException {
        Log.e(className, " readFileContent uri.getPath()=" + uri.getPath());
        InputStream inputStream =
                getContentResolver().openInputStream(uri);
        BufferedReader reader =
                new BufferedReader(new InputStreamReader(inputStream));
        StringBuilder stringBuilder = new StringBuilder();
        String currentline;
        while ((currentline = reader.readLine()) != null) {
            stringBuilder.append(currentline + "\n");
        }
        inputStream.close();
        return stringBuilder.toString();
    }

    public void saveFile(View view) {
        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        //intent.setType("text/plain");
        intent.setType(myMimeType);
        startActivityForResult(intent, SAVE_REQUEST_CODE);
    }

    private void writeFileContent(Uri uri) {
        Log.e(className, " writeFileContent uri.getPath()=" + uri.getPath());
        FileChannel inChannel = null;
        FileChannel outChannel = null;
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File expFile = new File("/storage/emulated/0/Android/data/org.hagerti.storagedemo/files" + File.separator + timeStamp + ".map");

        try {

            inChannel = new FileInputStream(getContentResolver().openFileDescriptor(uri, "r").getFileDescriptor()).getChannel();
            outChannel = new FileOutputStream(expFile).getChannel();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        try {
            inChannel.transferTo(0, inChannel.size(), outChannel);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (inChannel != null)
                try {
                    inChannel.close();
                    Log.e(className, " writeFileContent inChannel closed");
                } catch (IOException e) {
                    e.printStackTrace();
                }
            if (outChannel != null)
                try {
                    outChannel.close();
                    Log.e(className, " writeFileContent outChannel closed");
                } catch (IOException e) {
                    e.printStackTrace();
                }
        }
    }

}