在Java中检查文件夹权限的问题

Question

I am creating simple function to check weather I have write/delete permission to a folder

I want to know whether the operating system will allow writing into the folder or not ?

public static String PermissionCheck(String FilePath) {
    //File f = new File(FilePath);
    String actions = "read,write";
    try 
    {
      AccessController.checkPermission(new FilePermission(FilePath, actions));
      return ("You have read/write permition to use : " + FilePath);
    }
    catch (SecurityException e) 
    {
      return ("You don't have read/write permition to use : " + FilePath);
    }
}

When I call either with correct path or incorrect path the method it always returns message from cathc.

I know its duplicate question I have already gone through many links but no luck !!

Similar Question

Similar Question 1

Example :

PreChecks.PermissionCheck("C:/TEST/G2");
PreChecks.PermissionCheck("C:/Program Files/SAP");

Both calls return the message from catch block where I have all permission on "C:/TEST/G2" and no write permission on "C:/Program Files/SAP".

I have also tried canWrite but it says I have write permissions to "C:/Program Files/SAP" but I know I don't have those.

Answer 1

The class java.io.File is limited in its capabilities. Eg

File f=new File("C:\\Program Files\\Java");
System.out.println(f.canWrite());

prints true on my machine though a user process is not allowed to write at this location.

In contrast,

Path p=Paths.get("C:\\Program Files\\Java");
System.out.println(Files.isWritable(p));

correctly prints false .

So the solution is to use the NIO API.

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The method AccessController.checkPermission has an entirely different purpose. It helps implementing security managers. It throws a SecurityException because you don't have an explicitly granted permission to access that directory, but as long as you don't have a SecurityManager installed, that is irrelevant.