| /* |
| * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * 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. |
| * |
| * 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, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package javax.management; |
| |
| |
| import com.sun.jmx.mbeanserver.Introspector; |
| import java.io.IOException; |
| import java.io.ObjectInputStream; |
| |
| /** |
| * <p>Represents attributes used as arguments to relational constraints. |
| * Instances of this class are usually obtained using {@link Query#attr(String) |
| * Query.attr}.</p> |
| * |
| * <p>An <CODE>AttributeValueExp</CODE> may be used anywhere a |
| * <CODE>ValueExp</CODE> is required. |
| * |
| * @since 1.5 |
| */ |
| public class AttributeValueExp implements ValueExp { |
| |
| |
| /* Serial version */ |
| private static final long serialVersionUID = -7768025046539163385L; |
| |
| /** |
| * @serial The name of the attribute |
| */ |
| private String attr; |
| |
| /** |
| * An <code>AttributeValueExp</code> with a null attribute. |
| * @deprecated An instance created with this constructor cannot be |
| * used in a query. |
| */ |
| @Deprecated |
| public AttributeValueExp() { |
| } |
| |
| /** |
| * Creates a new <CODE>AttributeValueExp</CODE> representing the |
| * specified object attribute, named attr. |
| * |
| * @param attr the name of the attribute whose value is the value |
| * of this {@link ValueExp}. |
| */ |
| public AttributeValueExp(String attr) { |
| this.attr = attr; |
| } |
| |
| /** |
| * Returns a string representation of the name of the attribute. |
| * |
| * @return the attribute name. |
| */ |
| public String getAttributeName() { |
| return attr; |
| } |
| |
| /** |
| * <p>Applies the <CODE>AttributeValueExp</CODE> on an MBean. |
| * This method calls {@link #getAttribute getAttribute(name)} and wraps |
| * the result as a {@code ValueExp}. The value returned by |
| * {@code getAttribute} must be a {@code Number}, {@code String}, |
| * or {@code Boolean}; otherwise this method throws a |
| * {@code BadAttributeValueExpException}, which will cause |
| * the containing query to be false for this {@code name}.</p> |
| * |
| * @param name The name of the MBean on which the <CODE>AttributeValueExp</CODE> will be applied. |
| * |
| * @return The <CODE>ValueExp</CODE>. |
| * |
| * @throws BadStringOperationException {@inheritDoc} |
| * @throws BadBinaryOpValueExpException {@inheritDoc} |
| * @throws BadAttributeValueExpException {@inheritDoc} |
| * @throws InvalidApplicationException {@inheritDoc} |
| */ |
| @Override |
| public ValueExp apply(ObjectName name) throws BadStringOperationException, BadBinaryOpValueExpException, |
| BadAttributeValueExpException, InvalidApplicationException { |
| Object result = getAttribute(name); |
| |
| if (result instanceof Number) { |
| return new NumericValueExp((Number)result); |
| } else if (result instanceof String) { |
| return new StringValueExp((String)result); |
| } else if (result instanceof Boolean) { |
| return new BooleanValueExp((Boolean)result); |
| } else { |
| throw new BadAttributeValueExpException(result); |
| } |
| } |
| |
| /** |
| * Returns the string representing its value. |
| */ |
| @Override |
| public String toString() { |
| return attr; |
| } |
| |
| |
| /** |
| * Sets the MBean server on which the query is to be performed. |
| * |
| * @param s The MBean server on which the query is to be performed. |
| * |
| * @deprecated This method has no effect. The MBean Server used to |
| * obtain an attribute value is {@link QueryEval#getMBeanServer()}. |
| */ |
| /* There is no need for this method, because if a query is being |
| evaluted an AttributeValueExp can only appear inside a QueryExp, |
| and that QueryExp will itself have done setMBeanServer. */ |
| @Deprecated |
| @Override |
| public void setMBeanServer(MBeanServer s) { |
| } |
| |
| |
| /** |
| * <p>Return the value of the given attribute in the named MBean. |
| * If the attempt to access the attribute generates an exception, |
| * return null.</p> |
| * |
| * <p>The MBean Server used is the one returned by {@link |
| * QueryEval#getMBeanServer()}.</p> |
| * |
| * @param name the name of the MBean whose attribute is to be returned. |
| * |
| * @return the value of the attribute, or null if it could not be |
| * obtained. |
| */ |
| protected Object getAttribute(ObjectName name) { |
| try { |
| // Get the value from the MBeanServer |
| |
| MBeanServer server = QueryEval.getMBeanServer(); |
| |
| return server.getAttribute(name, attr); |
| } catch (Exception re) { |
| return null; |
| } |
| } |
| } |