InstanceOfQueryExp.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package javax.management;


/**
 * This class is used by the query building mechanism for isInstanceOf expressions.
 * @serial include
 *
 * @since 1.6
 */
class InstanceOfQueryExp extends QueryEval implements QueryExp {

    /* Serial version */
    private static final long serialVersionUID = -1081892073854801359L;

    /**
     * @serial The {@link StringValueExp} returning the name of the class
     *         of which selected MBeans should be instances.
     */
    private StringValueExp classNameValue;

    /**
     * Creates a new InstanceOfExp with a specific class name.
     * @param classNameValue The {@link StringValueExp} returning the name of
     *        the class of which selected MBeans should be instances.
     */
    // We are using StringValueExp here to be consistent with other queries,
    // although we should actually either use a simple string (the classname)
    // or a ValueExp - which would allow more complex queries - like for
    // instance evaluating the class name from an AttributeValueExp.
    // As it stands - using StringValueExp instead of a simple constant string
    // doesn't serve any useful purpose besides offering a consistent
    // look & feel.
    public InstanceOfQueryExp(StringValueExp classNameValue) {
        if (classNameValue == null) {
            throw new IllegalArgumentException("Null class name.");
        }

        this.classNameValue = classNameValue;
    }

    /**
     * Returns the class name.
     * @return The {@link StringValueExp} returning the name of
     *        the class of which selected MBeans should be instances.
     */
    public StringValueExp getClassNameValue()  {
        return classNameValue;
    }

    /**
     * Applies the InstanceOf on a MBean.
     *
     * @param name The name of the MBean on which the InstanceOf will be applied.
     *
     * @return  True if the MBean specified by the name is instance of the class.
     * @exception BadAttributeValueExpException
     * @exception InvalidApplicationException
     * @exception BadStringOperationException
     * @exception BadBinaryOpValueExpException
     */
    public boolean apply(ObjectName name)
        throws BadStringOperationException,
        BadBinaryOpValueExpException,
        BadAttributeValueExpException,
        InvalidApplicationException {

        // Get the class name value
        final StringValueExp val;
        try {
            val = (StringValueExp) classNameValue.apply(name);
        } catch (ClassCastException x) {
            // Should not happen - unless someone wrongly implemented
            // StringValueExp.apply().
            final BadStringOperationException y =
                    new BadStringOperationException(x.toString());
            y.initCause(x);
            throw y;
        }

        // Test whether the MBean is an instance of that class.
        try {
            return getMBeanServer().isInstanceOf(name, val.getValue());
        } catch (InstanceNotFoundException infe) {
            return false;
        }
    }

    /**
     * Returns a string representation of this InstanceOfQueryExp.
     * @return a string representation of this InstanceOfQueryExp.
     */
    public String toString() {
       return "InstanceOf " + classNameValue.toString();
   }
}