Question

我正在尝试使用以下代码在我的SD卡上创建一个文件夹，但它失败了。这是我用onCreate()编写的代码：

File test = new File(Environment.getExternalStorageDirectory(),"my_directory");
if(!test.exists())
{
    try 
    {
        if (test.mkdir()) 
        {
            Log.d("xxx", "directory created");
        } 
        else 
        {
             Log.d("xxx", "directory creation failed");
        }
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
}
else
{
    Log.d("xxx","directory already present");
}

当我运行上面的代码时没有给出任何异常，它只是打印出来的 directory creation failed日志。

我也给了以下许可，

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

我使用的是小米Redmi note 3，Android版本是6.0.1。

Answer 1

试试此代码

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

         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                        if (checkPermission()) {
                            //do your work
                        } else {
                            requestPermission();
                        }
                    }
           }


            protected boolean checkPermission() {
                int result = ContextCompat.checkSelfPermission(this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE);
                if (result == PackageManager.PERMISSION_GRANTED) {
                    return true;
                } else {
                    return false;
                }
            }

            protected void requestPermission() {

                if (ActivityCompat.shouldShowRequestPermissionRationale(this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
                    Toast.makeText(this, "Write External Storage permission allows us to do store images. Please allow this permission in App Settings.", Toast.LENGTH_LONG).show();
                } else {
                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                        requestPermissions(new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, 100);
                    }
                }
            }

        @Override
        public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
            switch (requestCode) {
                case 100:
                    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                        //do your work
                    } else {
                        Log.e("value", "Permission Denied, You cannot use local drive .");
                    }
                    break;
            }
        }

Answer 2

我只知道API 21（我想在我的应用程序中也一样，直到现在我不知道如何使用SD卡）

你的清单中也需要这个!!

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

Environment.getExternalStorageDirectory()声明内部存储空间。确切的路径是：storage / emulated / 0 你得到它：

Log.i(TAG, "path is:" + Environment.getExternalStorageDirectory().toString());

无法在Android（在MarshMallow及更高版本）设备上创建目录

2 个答案: