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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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package java.security;

A GuardedObject is an object that is used to protect access to
another object.
A GuardedObject encapsulates a target object and a Guard object, such that access to the target object is possible only if the Guard object allows it. Once an object is encapsulated by a GuardedObject, access to that object is controlled by the getObject method, which invokes the checkGuard method on the Guard object that is guarding access. If access is not allowed, an exception is thrown. 
Author:
Roland Schemers, Li Gong
See Also:
Guard
Permission
Since:
1.2/**
 * A GuardedObject is an object that is used to protect access to
 * another object.
 *
 * <p>A GuardedObject encapsulates a target object and a Guard object,
 * such that access to the target object is possible
 * only if the Guard object allows it.
 * Once an object is encapsulated by a GuardedObject,
 * access to that object is controlled by the {@code getObject}
 * method, which invokes the
 * {@code checkGuard} method on the Guard object that is
 * guarding access. If access is not allowed,
 * an exception is thrown.
 *
 * @see Guard
 * @see Permission
 *
 * @author Roland Schemers
 * @author Li Gong
 * @since 1.2
 */

public class GuardedObject implements java.io.Serializable {

    private static final long serialVersionUID = -5240450096227834308L;

    private Object object; // the object we are guarding
    private Guard guard;   // the guard

    
Constructs a GuardedObject using the specified object and guard.
If the Guard object is null, then no restrictions will
be placed on who can access the object.
Params:
object – the object to be guarded.
guard – the Guard object that guards access to the object./**
     * Constructs a GuardedObject using the specified object and guard.
     * If the Guard object is null, then no restrictions will
     * be placed on who can access the object.
     *
     * @param object the object to be guarded.
     *
     * @param guard the Guard object that guards access to the object.
     */

    public GuardedObject(Object object, Guard guard)
    {
        this.guard = guard;
        this.object = object;
    }

    
Retrieves the guarded object, or throws an exception if access
to the guarded object is denied by the guard.
Throws:
SecurityException – if access to the guarded object is
denied.
Returns:
the guarded object./**
     * Retrieves the guarded object, or throws an exception if access
     * to the guarded object is denied by the guard.
     *
     * @return the guarded object.
     *
     * @exception SecurityException if access to the guarded object is
     * denied.
     */
    public Object getObject()
        throws SecurityException
    {
        if (guard != null)
            guard.checkGuard(object);

        return object;
    }

    
Writes this object out to a stream (i.e., serializes it).
We check the guard if there is one.
/**
     * Writes this object out to a stream (i.e., serializes it).
     * We check the guard if there is one.
     */
    private void writeObject(java.io.ObjectOutputStream oos)
        throws java.io.IOException
    {
        if (guard != null)
            guard.checkGuard(object);

        oos.defaultWriteObject();
    }
}