With this example we are going to demonstrate how to control access to an Object in Java. In short, to control access to an Object you should:
- Create a Guard, which is an object that is used to protect access to another object, with the String name of the system property, and a String of comma-separated actions granted on the property.
- Create a GuardedObject to encapsulate the target object and the Guard object. In this example the target object is a String password.
- In order to get the guarded object, we can invoke the
getObject()API method of the GuardedObject. If the access to the object is not allowed, an AccessControlException is thrown.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.core;
import java.security.AccessControlException;
import java.security.Guard;
import java.security.GuardedObject;
import java.util.PropertyPermission;
public class ControlAccessToObject {
public static void main(String[] args) {
// The object that requires protection
String password = new String("my_password");
/* The permission that will protect the object. In this case everyone (thread)
who has read access to the "java.home" environment variable can
access the object as well
*/
Guard guard = new PropertyPermission("java.home", "read");
// Create the guard
GuardedObject guardedObject = new GuardedObject(password, guard);
// Get the guarded object, only threads with the required permission can access the object.
try {
password = (String) guardedObject.getObject();
System.out.println("Protected object is " + password);
} catch (AccessControlException e) {
System.out.println("Cannot access the object - permission is denied");
}
}
}
Output:
Protected object is my_password
This was an example of how to control access to an Object in Java.
