<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
 
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
        tools:ignore="ScopedStorage" /><!--add 2022-2-11 Android11-->
 
<application
    ...
    android:requestLegacyExternalStorage="true" 
    ...
    >

代碼申請動態(tài)權限

1.Android 6.0之上Android11以下申請權限

 if (Build.VERSION.SDK_INT >= 23) {// 6.0
        String[] perms = {
                Manifest.permission.READ_EXTERNAL_STORAGE,
                Manifest.permission.WRITE_EXTERNAL_STORAGE,
                Manifest.permission.READ_PHONE_STATE};
        for (String p : perms) {
            int f = ContextCompat.checkSelfPermission(SafeKeyToolActivity.this, p);
            Log.d("---", String.format("%s - %d", p, f));
            if (f != PackageManager.PERMISSION_GRANTED) {
                requestPermissions(perms, 0XCF);
                break;
            }
        }
    }

Android11申請權限

跳轉系統(tǒng)設置界面，用戶授權獲取權限。

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R && !isRefuse) {// android 11  且 不是已經(jīng)被拒絕
        // 先判斷有沒有權限
        if (!Environment.isExternalStorageManager()) {
            Intent intent = new Intent(Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION);
            intent.setData(Uri.parse("package:" + getPackageName()));
            startActivityForResult(intent, 1024);
        }
    }
 
// 帶回授權結果
 @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 1024 && Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
    	// 檢查是否有權限
        if (Environment.isExternalStorageManager()) {
            isRefuse = false;
            // 授權成功
        } else {
            isRefuse = true;
            // 授權失敗
        }
    }
}

對于部分手機如小米手機，即使獲取了所有文件的管理權限，依舊訪問不到Android/data目錄，如圖：

嘗試解決辦法：

只在外部存儲的應用私有目錄下，用直接路徑讀寫文件。

訪問或者共享媒體文件，使用MediaStore在公共目錄下讀寫文件

訪問或者共享非媒體文件，使用系統(tǒng)的文件選擇器SAF在公共目錄Download下讀寫文件。

根目錄下可以創(chuàng)建自定義文件夾、文件。

補充：Android 11 及以上申請外部存儲權限

升級 targetSdkVersion

android 
    defaultConfig {
        targetSdkVersion 30
    }
}

添加清單權限

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

代碼動態(tài)申請

public final class PermissionActivity extends AppCompatActivity {

    private static final int REQUEST_CODE = 1024;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestPermission();
    }

    private void requestPermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
            // 先判斷有沒有權限
            if (Environment.isExternalStorageManager()) {
                writeFile();
            } else {
                Intent intent = new Intent(Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION);
                intent.setData(Uri.parse("package:" + context.getPackageName()));
                startActivityForResult(intent, REQUEST_CODE);
            }
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            // 先判斷有沒有權限
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED &&
                    ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
                writeFile();
            } else {
                ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE);
            }
        } else {
            writeFile();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUEST_CODE) {
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED &&
                    ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
                writeFile();
            } else {
                ToastUtils.show("存儲權限獲取失敗");
            }
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_CODE && Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
            if (Environment.isExternalStorageManager()) {
                writeFile();
            } else {
                ToastUtils.show("存儲權限獲取失敗");
            }
        }
    }

    /**
     * 模擬文件寫入
     */
    private void writeFile() {
        ToastUtils.show("寫入文件成功");
    }
}