| /* |
| * Copyright (c) 1999, 2004, 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; |
| |
| |
| /** |
| * Represents values that can be passed as arguments to |
| * relational expressions. Strings, numbers, attributes are valid values |
| * and should be represented by implementations of <CODE>ValueExp</CODE>. |
| * |
| * @since 1.5 |
| */ |
| /* |
| We considered generifying this interface as ValueExp<T>, where T is |
| the Java type that this expression generates. This allows some additional |
| checking in the various methods of the Query class, but in practice |
| not much. Typically you have something like |
| Query.lt(Query.attr("A"), Query.value(5)). We can arrange for Query.value |
| to have type ValueExp<Integer> (or maybe ValueExp<Long> or ValueExp<Number>) |
| but for Query.attr we can't do better than ValueExp<?> or plain ValueExp. |
| So even though we could define Query.lt as: |
| QueryExp <T> lt(ValueExp<T> v1, ValueExp<T> v2) |
| and thus prevent comparing a |
| number against a string, in practice the first ValueExp will almost always |
| be a Query.attr so this check serves no purpose. You would have to |
| write Query.<Number>attr("A"), for example, which would be awful. And, |
| if you wrote Query.<Integer>attr("A") you would then discover that you |
| couldn't compare it against Query.value(5) if the latter is defined as |
| ValueExp<Number>, or against Query.value(5L) if it is defined as |
| ValueExp<Integer>. |
| |
| Worse, for Query.in we would like to define: |
| QueryExp <T> in(ValueExp<T> val, ValueExp<T>[] valueList) |
| but this is unusable because you cannot write |
| "new ValueExp<Integer>[] {...}" (the compiler forbids it). |
| |
| The few mistakes you might catch with this generification certainly |
| wouldn't justify the hassle of modifying user code to get the checks |
| to be made and the "unchecked" warnings that would arise if it |
| wasn't so modified. |
| |
| We could reconsider this if the Query methods were augmented, for example |
| with: |
| AttributeValueExp<Number> numberAttr(String name); |
| AttributeValueExp<String> stringAttr(String name); |
| AttributeValueExp<Boolean> booleanAttr(String name); |
| QueryExp <T> in(ValueExp<T> val, Set<ValueExp<T>> valueSet). |
| But it's not really clear what numberAttr should do if it finds that the |
| attribute is not in fact a Number. |
| */ |
| public interface ValueExp extends java.io.Serializable { |
| |
| /** |
| * Applies the ValueExp on a MBean. |
| * |
| * @param name The name of the MBean on which the ValueExp will be applied. |
| * |
| * @return The <CODE>ValueExp</CODE>. |
| * |
| * @exception BadStringOperationException |
| * @exception BadBinaryOpValueExpException |
| * @exception BadAttributeValueExpException |
| * @exception InvalidApplicationException |
| */ |
| public ValueExp apply(ObjectName name) |
| throws BadStringOperationException, BadBinaryOpValueExpException, |
| BadAttributeValueExpException, InvalidApplicationException; |
| |
| /** |
| * 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 is not needed because a |
| * <code>ValueExp</code> can access the MBean server in which it |
| * is being evaluated by using {@link QueryEval#getMBeanServer()}. |
| */ |
| @Deprecated |
| public void setMBeanServer(MBeanServer s) ; |
| } |