diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/java.management/share/classes/javax/management/AttributeValueExp.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/java.management/share/classes/javax/management/AttributeValueExp.java Tue Sep 12 19:03:39 2017 +0200 @@ -0,0 +1,167 @@ +/* + * 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; + +/** + *

Represents attributes used as arguments to relational constraints. + * Instances of this class are usually obtained using {@link Query#attr(String) + * Query.attr}.

+ * + *

An AttributeValueExp may be used anywhere a + * ValueExp 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 AttributeValueExp with a null attribute. + * @deprecated An instance created with this constructor cannot be + * used in a query. + */ + @Deprecated + public AttributeValueExp() { + } + + /** + * Creates a new AttributeValueExp 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; + } + + /** + *

Applies the AttributeValueExp 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}.

+ * + * @param name The name of the MBean on which the AttributeValueExp will be applied. + * + * @return The ValueExp. + * + * @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) { + } + + + /** + *

Return the value of the given attribute in the named MBean. + * If the attempt to access the attribute generates an exception, + * return null.

+ * + *

The MBean Server used is the one returned by {@link + * QueryEval#getMBeanServer()}.

+ * + * @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; + } + } +}