Change permission of a created file so only the current user can read it

I need to set the permission to read a file to a specific user of the operating system, how can I do this in Java?

Edit: The file will be created with permissions just to the user running the application, than it needs to set read permission to a single user, other users will 开发者_Python百科not have the permissions to read the file.

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Use the methods setExecutable, setReadable, and setWritable in java.io.File. You can use these to change any permission bit of a file you own. Direct link: http://download.oracle.com/javase/6/docs/api/java/io/File.html#setReadable%28boolean%29. Testing this on MacOSX revels that only the user read value is changed. When program

import java.io.File;

public class Test
{
    public static void main(String[] args)
    {
        File f = new File("test.txt");
        f.setReadable(true);
    }
}

the folloiwng happens.

$ touch test.txt
$ chmod 000 test.txt


$ javac Test.java
$ java Test
$ ls -l test.txt
-r--------  1 morrison  staff  0 Jun  7 13:28 test.txt

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If you're targetting Windows Vista/7, build your JAR as EXE and embed a manifest requesting for Admin rights. If it's just an I/O problem, use the default File methods setReadable, setWritable, setExecutable :)

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In regards to making the permissions for a single user, start with using ncmathsadist's code to add read permissions, then change the owner of the file to whoever needs access.

I found in the Ant source code they use for the change-owner task. For unix this can be found in the Ant source tree at org/apache/tools/ant/taskdefs/optional/unix/Chown.java. You might be able to include this and use it as an API call to change the user programmatically.

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if you want to change file permissions on old Java versions like Java 5, you can use this:

Runtime.getRuntime().exec("chmod 000 " + PATH + fileName);

on windows you'll have to replace chmod with the appropriate CACLS.exe command syntax