即使具有给定的权限，也无法在外部存储上进行读/写 [英] Cannot READ/WRITE on External Storage, even having given Permissions

问题描述

在Huawei Mate 20上运行我的应用程序，以下行:

Running my App on a Huawei Mate 20, the following lines:

    String ext_path = Environment.getExternalStorageDirectory().getAbsolutePath();
    File ext_folder = new File(ext_path);
    System.out.println("Path: " + ext_path + " Dir Check: " + ext_folder.isDirectory() + " Can read: " + ext_folder.canRead());

返回:路径:/storage/emulated/0目录检查:true可以读取:false"

Return: "Path: /storage/emulated/0 Dir Check: true Can read: false"

但是，我已经授予了所有权限，并且还将这些权限包括在清单中:

However, I have given all permissions and I have also included these in the manifest:

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

不能Read()返回True吗?我无法写入或读取文件.可能是什么原因?

Shouldn't canRead() return True? I cannot write or read files. What could be the reason?

我也尝试过:

    String extStore = System.getenv("EXTERNAL_STORAGE");
    File f_exts = new File(extStore);
    System.out.println(f_exts);
    System.out.println(Arrays.toString(f_exts.listFiles()));

我得到:"EXTERNAL_STORAGE"和"null"

and I get: "EXTERNAL_STORAGE" and "null"

推荐答案

，您需要明确要求用户授予所述权限.否则它将无法在较新的android vesions中工作.尝试在onCreate中添加此内容

you need to explicitly ask the user to grant said permissions. else it wont work in newer android vesions.try adding this in onCreate

ActivityCompat.requestPermissions(MainActivity.this, new String[]{READ_EXTERNAL_STORAGE, WRITE_EXTERNAL_STORAGE},111);

还有

如果您要定位Android Q，那么Environment.getExternalStorageDirectory()不再导致可访问的文件夹，我认为这实际上是您的问题.不推荐使用它，而推荐使用Context.getExternalFilesDir(null)来返回文件.值得一试，因为您的应用程序外部存储应该类似于"/storage/emulated/0/Android/data/com.example.android.YourApp/"，并且在该位置您应该具有读写访问权限

If you are TARGETING Android Q also Environment.getExternalStorageDirectory() no longer leading to an accessible folder, which i think is actually your problem. it is deprecated in favor of Context.getExternalFilesDir(null) which returns a file. that is worth a try as your apps external storage should be something like "/storage/emulated/0/Android/data/com.example.android.YourApp/" and on that one you should have read and write access

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