SecurityManager checkPermission() Method

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Description

The java.lang.SecurityManager.checkPermission(Permission perm, Object context) method throws a SecurityException if the specified security context is denied access to the resource specified by the given permission. The context must be a security context returned by a previous call to getSecurityContext and the access control decision is based upon the configured security policy for that security context.

If context is an instance of AccessControlContext then the AccessControlContext.checkPermission method is invoked with the specified permission. If context is not an instance of AccessControlContext then a SecurityException is thrown.

Declaration

Following is the declaration for java.lang.SecurityManager.checkPermission() method

public void checkPermission(Permission perm, Object context)

Parameters

• perm − the requested permission.

• context − a system-dependent security context.

Return Value

This method does not return a value.

Exception

• SecurityException − if the specified security context is not an instance of AccessControlContext (e.g., is null), or is denied access to the resource specified by the given permission.

• NullPointerException − if the permission argument is null.

Example

Our examples require that the permissions for each command is blocked. A new policy file was set that allows only the creating and setting of our Security Manager. The file is in C:/java.policy and contains the following text −

grant {
   permission java.lang.RuntimePermission "setSecurityManager";
   permission java.lang.RuntimePermission "createSecurityManager";
   permission java.lang.RuntimePermission "usePolicy";
};

The following example shows the usage of lang.SecurityManager.checkPermission() method.

package com.tutorialspoint;

import java.io.FilePermission;
import java.security.AccessControlContext;
import java.security.AccessController;

public class SecurityManagerDemo extends SecurityManager {

   public static void main(String[] args) {

      // get current security context
      AccessControlContext con = AccessController.getContext();

      // set the policy file as the system securuty policy
      System.setProperty("java.security.policy", "file:/C:/java.policy");

      // create a security manager
      SecurityManagerDemo sm = new SecurityManagerDemo();

      // set the system security manager
      System.setSecurityManager(sm);

      // perform the check
      sm.checkPermission(new FilePermission("test.txt", "read,write"), con);

      // print a message if we passed the check
      System.out.println("Allowed!");
   }
}

Let us compile and run the above program, this will produce the following result −

Exception in thread "main" java.security.AccessControlException: access denied (java.io.FilePermission test.txt read,write)