1 /*
2 * Copyright 1999-2004 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package javax.management;
27
28
29 /**
30 * Represents values that can be passed as arguments to
31 * relational expressions. Strings, numbers, attributes are valid values
32 * and should be represented by implementations of <CODE>ValueExp</CODE>.
33 *
34 * @since 1.5
35 */
36 /*
37 We considered generifying this interface as ValueExp<T>, where T is
38 the Java type that this expression generates. This allows some additional
39 checking in the various methods of the Query class, but in practice
40 not much. Typically you have something like
41 Query.lt(Query.attr("A"), Query.value(5)). We can arrange for Query.value
42 to have type ValueExp<Integer> (or maybe ValueExp<Long> or ValueExp<Number>)
43 but for Query.attr we can't do better than ValueExp<?> or plain ValueExp.
44 So even though we could define Query.lt as:
45 QueryExp <T> lt(ValueExp<T> v1, ValueExp<T> v2)
46 and thus prevent comparing a
47 number against a string, in practice the first ValueExp will almost always
48 be a Query.attr so this check serves no purpose. You would have to
49 write Query.<Number>attr("A"), for example, which would be awful. And,
50 if you wrote Query.<Integer>attr("A") you would then discover that you
51 couldn't compare it against Query.value(5) if the latter is defined as
52 ValueExp<Number>, or against Query.value(5L) if it is defined as
53 ValueExp<Integer>.
54
55 Worse, for Query.in we would like to define:
56 QueryExp <T> in(ValueExp<T> val, ValueExp<T>[] valueList)
57 but this is unusable because you cannot write
58 "new ValueExp<Integer>[] {...}" (the compiler forbids it).
59
60 The few mistakes you might catch with this generification certainly
61 wouldn't justify the hassle of modifying user code to get the checks
62 to be made and the "unchecked" warnings that would arise if it
63 wasn't so modified.
64
65 We could reconsider this if the Query methods were augmented, for example
66 with:
67 AttributeValueExp<Number> numberAttr(String name);
68 AttributeValueExp<String> stringAttr(String name);
69 AttributeValueExp<Boolean> booleanAttr(String name);
70 QueryExp <T> in(ValueExp<T> val, Set<ValueExp<T>> valueSet).
71 But it's not really clear what numberAttr should do if it finds that the
72 attribute is not in fact a Number.
73 */
74 public interface ValueExp extends java.io.Serializable {
75
76 /**
77 * Applies the ValueExp on a MBean.
78 *
79 * @param name The name of the MBean on which the ValueExp will be applied.
80 *
81 * @return The <CODE>ValueExp</CODE>.
82 *
83 * @exception BadStringOperationException
84 * @exception BadBinaryOpValueExpException
85 * @exception BadAttributeValueExpException
86 * @exception InvalidApplicationException
87 */
88 public ValueExp apply(ObjectName name)
89 throws BadStringOperationException, BadBinaryOpValueExpException,
90 BadAttributeValueExpException, InvalidApplicationException;
91
92 /**
93 * Sets the MBean server on which the query is to be performed.
94 *
95 * @param s The MBean server on which the query is to be performed.
96 *
97 * @deprecated This method is not needed because a
98 * <code>ValueExp</code> can access the MBean server in which it
99 * is being evaluated by using {@link QueryEval#getMBeanServer()}.
100 */
101 @Deprecated
102 public void setMBeanServer(MBeanServer s) ;
103 }
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