java ContextCompat。尽管已授予写入外部存储，checkSelfPermission返回1

Question

在电话设置中授予权限。安卓8.0手机

compileSdkVersion 28
minSdkVersion 16
targetSdkVersion 28

舱单有：

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

在我的代码中，此“permissions”变量始终等于-1：

int permissions = ContextCompat.checkSelfPermission(getContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE);

Answer 1

好的，感谢Larry Schiefer提供的运行时权限

考虑到android文档：

link 1 link 2

我对链接2中的方法做了一些更改。在执行某些操作之前，它会检查权限，必要时会要求用户确认，在其他情况下，它会强制设置权限

    public void requestRuntimePermission(final Context context, final String manifestPermission, final int requestCode) {

        int permissions = ContextCompat.checkSelfPermission(context, manifestPermission);
        if (permissions != PackageManager.PERMISSION_GRANTED) {

            if (ActivityCompat.shouldShowRequestPermissionRationale((Activity) context,
                    manifestPermission)) {

                android.support.v7.app.AlertDialog.Builder builder = new android.support.v7.app.AlertDialog.Builder(context);
                builder.setMessage("Allow access?")
                        .setCancelable(true)
                        //Cancel
                        .setNegativeButton("Yes", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                            }
                        })
                        //Ok
                        .setPositiveButton("No", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                                ActivityCompat.requestPermissions((Activity) context,
                                        new String[]{manifestPermission},
                                        requestCode);
                            }
                        });
                android.support.v7.app.AlertDialog alert = builder.create();
                alert.show();

            } else {
                // Permission has not been granted yet. Request it directly.
                ActivityCompat.requestPermissions((Activity) context, new String[]{manifestPermission},
                        requestCode);
            }

        }
    }

用法示例：

requestRuntimePermission(getContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE, 0);

requestRuntimePermission中的p.S.requestCode参数可用于标识onRequestPermissionsResult回调中允许的权限。（link 3）

Answer 2

从Android 6（API 23）开始，您还必须在运行时请求此权限。此视频可能有帮助：https://youtu.be/WGz-alwVh8A