Android Studio SD卡访问权限及asserts文件夹下的文件操作

最新推荐文章于 2023-11-14 19:10:03 发布

GondorFu

最新推荐文章于 2023-11-14 19:10:03 发布

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分类专栏：实用工具文章标签： Android

本文链接：https://blog.youkuaiyun.com/a40850273/article/details/81390132

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本文介绍如何在Android应用中获取SD卡读写权限，并提供了实现代码示例。此外，还介绍了如何从assets文件夹复制文件到SD卡的具体步骤。

Android Studio SD卡访问权限

1、在 AndroidManifext.xml 中添加如下代码

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

其分别表示 SD 卡的写，读和创建/删除文件权限

2、请求用户授予 SD 卡读写权限

    @SuppressLint("NewApi")
    private void requestReadExternalPermission() {
        if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            Log.d(TAG, "READ permission IS NOT granted...");
            requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 0);

        } else {
            Log.d(TAG, "READ permission is granted...");
        }
    }

    @SuppressLint("NewApi")
    private void requestWriteExternalPermission() {
        if (checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            Log.d(TAG, "WRITE permission IS NOT granted...");
            requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);

        } else {
            Log.d(TAG, "WRITE permission is granted...");
        }
    }

3、操作asserts下的文件（将asserts文件夹下 data 文件夹下的所有文件复制到SD卡中）


        systemPath = Environment.getExternalStorageDirectory() + "/";
        appFolderPath = systemPath + "AppClassificationAssets/";

        // create assets folder if it doesn't exist
        createAssetsFolder();

        // copy all data files from assets to external storage
        try {
            String[] list = getAssets().list("data");
            for (String file: list) {
                copyToExternalStorage(file, "data");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    

    private void createAssetsFolder(){
        // create app assets folder if not created
        File folder = new File(appFolderPath);

        if (!folder.exists()) {
            Log.d(TAG,"AppClassificationAssets folder does not exist, creating one");
            folder.mkdirs();
        } else {
            Log.w(TAG,"INFO: AppClassificationAssets folder already exists.");
        }
    }

    private void copyToExternalStorage(String assetName, String assetsDirectory){
        String from = assetName;
        String to = appFolderPath+from;

        // check if the file exists
        File file = new File(to);
        if(file.exists()){
            Log.d(TAG, "copyToExternalStorage: file already exist, no need to copy: "+from);
        } else {
            // do copy
            boolean copyResult = copyAsset(getAssets(), from, assetsDirectory, to);
            Log.d(TAG, "copyToExternalStorage: isCopied -> "+copyResult);
        }
    }

    private boolean copyAsset(AssetManager assetManager, String fromAssetPath, String assetsDirectory, String toPath) {
        InputStream inputStream = null;
        OutputStream outputStream = null;
        try {
            inputStream = assetManager.open(assetsDirectory+"/"+fromAssetPath);
            new File(toPath).createNewFile();
            outputStream = new FileOutputStream(toPath);
            copyFile(inputStream, outputStream);
            inputStream.close();
            outputStream.flush();
            outputStream.close();
            return true;
        } catch(Exception e) {
            e.printStackTrace();
            Log.e(TAG, "copyAsset: unable to copy file: "+fromAssetPath);
            return false;
        }
    }

    private void copyFile(InputStream inputStream, OutputStream outputStream) throws IOException {
        byte[] buffer = new byte[1024];
        int read;
        while ((read = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, read);
        }
    }