/*
 * @(#)ClassAttributeValueExp.java	4.25 06/02/07
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.management;

import java.security.AccessController;
import java.security.PrivilegedAction;

import com.sun.jmx.mbeanserver.GetPropertyAction;

/**
 * This class represents the name of the Java implementation class of
 * the MBean. It is used for performing queries based on the class of
 * the MBean.
 * @serial include
 *
 * <p>The <b>serialVersionUID</b> of this class is <code>-1081892073854801359L</code>.
 * 
 * @since 1.5
 */
class ClassAttributeValueExp extends AttributeValueExp {

    // Serialization compatibility stuff:
    // Two serial forms are supported in this class. The selected form depends
    // on system property "jmx.serial.form":
    //  - "1.0" for JMX 1.0
    //  - any other value for JMX 1.1 and higher
    //
    // Serial version for old serial form
    private static final long oldSerialVersionUID = -2212731951078526753L;
    //
    // Serial version for new serial form
    private static final long newSerialVersionUID = -1081892073854801359L;

    private static final long serialVersionUID;
    static {
	boolean compat = false;
	try {
	    GetPropertyAction act = new GetPropertyAction("jmx.serial.form");
	    String form = AccessController.doPrivileged(act);
	    compat = (form != null && form.equals("1.0"));
	} catch (Exception e) {
	    // OK: exception means no compat with 1.0, too bad
	}
	if (compat)
	    serialVersionUID = oldSerialVersionUID;
	else
	    serialVersionUID = newSerialVersionUID;
    }

    /**
     * @serial The name of the attribute
     *
     * <p>The <b>serialVersionUID</b> of this class is <code>-1081892073854801359L</code>.
     */
    private String attr;

    /**
     * Basic Constructor.
     */
    public ClassAttributeValueExp() {
	/* Compatibility: we have an attr field that we must hold on to
	   for serial compatibility, even though our parent has one too.  */
	super("Class");
	attr = "Class";
    }


    /**
     * Applies the ClassAttributeValueExp on an MBean. Returns the name of
     * the Java implementation class of the MBean.
     *
     * @param name The name of the MBean on which the ClassAttributeValueExp will be applied.
     *
     * @return  The ValueExp.
     *
     * @exception BadAttributeValueExpException
     * @exception InvalidApplicationException
     */
    public ValueExp apply(ObjectName name)
	    throws BadStringOperationException, BadBinaryOpValueExpException,
		   BadAttributeValueExpException, InvalidApplicationException {
	// getAttribute(name);
	Object result = getValue(name);
	if  (result instanceof String) {
	    return new StringValueExp((String)result);
	} else {
	    throw new BadAttributeValueExpException(result);
	}
    }

    /**
     * Returns the string "Class" representing its value
     */
    public String toString()  {
	return attr;