OpenMBeanOperationInfoSupport


1   /*
2    * @(#)OpenMBeanOperationInfoSupport.java   3.25 03/12/19
3    * 
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   
9   package javax.management.openmbean;
10  
11  
12  // java import
13  //
14  import java.io.Serializable  ;
15  import java.util.Arrays  ;
16  
17  // jmx import
18  //
19  import javax.management.MBeanOperationInfo  ;
20  import javax.management.MBeanParameterInfo  ;
21  
22  
23  /**
24   * Describes an operation of an Open MBean.
25   *
26   * @version     3.25  03/12/19
27   * @author      Sun Microsystems, Inc.
28   *
29   * @since 1.5
30   * @since.unbundled JMX 1.1
31   */
32  public class OpenMBeanOperationInfoSupport 
33      extends MBeanOperationInfo   
34      implements OpenMBeanOperationInfo  , Serializable   {
35      
36      
37      /* Serial version */
38      static final long serialVersionUID = 4996859732565369366L;
39  
40      /**
41       * @serial The <i>open type</i> of the values returned by the operation 
42       *         described by this {@link OpenMBeanOperationInfo} instance
43       *
44       */
45      private OpenType   returnOpenType;
46  
47  
48      private transient Integer   myHashCode = null;    // As this instance is immutable, these two values
49      private transient String    myToString = null;    // need only be calculated once.
50  
51  
52      /**
53       * Constructs an <tt>OpenMBeanOperationInfoSupport</tt> instance, which describes the operation 
54       * of a class of open MBeans, with the specified 
55       * <var>name</var>, <var>description</var>, <var>signature</var>, <var>returnOpenType</var> and <var>impact</var>.
56       * <p>
57       * The <var>signature</var> array parameter is internally copied, so that subsequent changes 
58       * to the array referenced by <var>signature</var> have no effect on this instance.
59       * <p>
60       *
61       * @param name  cannot be a null or empty string.
62       *
63       * @param description  cannot be a null or empty string.
64       *
65       * @param signature  can be null or empty if there are no parameters to describe.
66       *
67       * @param returnOpenType  cannot be null: use <tt>SimpleType.VOID</tt> for operations that return nothing.
68       *
69       * @param impact can be only one of <tt>ACTION</tt>, <tt>ACTION_INFO</tt> or <tt>INFO</tt>.
70       *
71       * @throws IllegalArgumentException  if <var>name</var> or <var>description</var> are null or empty string,
72       *                   or <var>returnOpenType</var> is null,
73       *                   or <var>impact</var> is not one of <tt>ACTION</tt>, <tt>ACTION_INFO</tt> or <tt>INFO</tt>.
74       *
75       * @throws ArrayStoreException  If <var>signature</var> is not an array of instances of a subclass of <tt>MBeanParameterInfo</tt>.
76       */
77      public OpenMBeanOperationInfoSupport(String   name, 
78                       String   description,
79                       OpenMBeanParameterInfo  [] signature,
80                       OpenType   returnOpenType,
81                       int impact) {
82  
83      super(name, 
84            description,
85            ( signature == null ?  null : arrayCopyCast(signature) ), // may throw an ArrayStoreException
86            ( returnOpenType == null ?  null : returnOpenType.getClassName() ),
87            impact);
88  
89      // check parameters that should not be null or empty (unfortunately it is not done in superclass :-( ! )
90      //
91      if ( (name == null) || (name.trim().equals("")) ) {
92          throw new IllegalArgumentException  ("Argument name cannot be null or empty.");
93      }
94      if ( (description == null) || (description.trim().equals("")) ) {
95          throw new IllegalArgumentException  ("Argument description cannot be null or empty.");
96      }
97      if (returnOpenType == null) {
98          throw new IllegalArgumentException  ("Argument returnOpenType cannot be null.");
99      }
100 
101     // check impact's value is only one of the 3 allowed (UNKNOWN not allowed)
102     //
103     if ( (impact != super.ACTION) && (impact != super.ACTION_INFO) && (impact != super.INFO) ) {
104         throw new IllegalArgumentException  ("Argument impact can be only one of ACTION, ACTION_INFO or INFO.");
105     }
106 
107     this.returnOpenType = returnOpenType;
108     }
109 
110 
111     private static MBeanParameterInfo  [] arrayCopyCast(OpenMBeanParameterInfo  [] src) throws ArrayStoreException   {
112 
113     MBeanParameterInfo  [] dst = new MBeanParameterInfo  [src.length];
114     System.arraycopy(src, 0, dst, 0, src.length); // may throw an ArrayStoreException
115     return dst;
116     }
117 
118 
119     // [JF]: should we add constructor with java.lang.reflect.Method method parameter ?
120     // would need to add consistency check between OpenType returnOpenType and mehtod.getReturnType().
121 
122 
123     /**
124      * Returns the <i>open type</i> of the values returned by the operation described by this <tt>OpenMBeanOperationInfo</tt> instance.
125      */
126     public OpenType   getReturnOpenType() { 
127 
128     return returnOpenType;
129     }
130 
131 
132 
133     /* ***  Commodity methods from java.lang.Object  *** */
134 
135 
136     /**
137      * Compares the specified <var>obj</var> parameter with this <code>OpenMBeanOperationInfoSupport</code> instance for equality. 
138      * <p>
139      * Returns <tt>true</tt> if and only if all of the following statements are true:
140      * <ul>
141      * <li><var>obj</var> is non null,</li>
142      * <li><var>obj</var> also implements the <code>OpenMBeanOperationInfo</code> interface,</li>
143      * <li>their names are equal</li>
144      * <li>their signatures are equal</li>
145      * <li>their return open types are equal</li>
146      * <li>their impacts are equal</li>
147      * </ul>
148      * This ensures that this <tt>equals</tt> method works properly for <var>obj</var> parameters which are
149      * different implementations of the <code>OpenMBeanOperationInfo</code> interface.
150      * <br>&nbsp;
151      * @param  obj  the object to be compared for equality with this <code>OpenMBeanOperationInfoSupport</code> instance;
152      * 
153      * @return  <code>true</code> if the specified object is equal to this <code>OpenMBeanOperationInfoSupport</code> instance.
154      */
155     public boolean equals(Object   obj) { 
156 
157     // if obj is null, return false
158     //
159     if (obj == null) {
160         return false;
161     }
162 
163     // if obj is not a OpenMBeanOperationInfo, return false
164     //
165     OpenMBeanOperationInfo   other;
166     try {
167         other = (OpenMBeanOperationInfo  ) obj;
168     } catch (ClassCastException   e) {
169         return false;
170     }
171 
172     // Now, really test for equality between this OpenMBeanOperationInfo implementation and the other:
173     //
174     
175     // their Name should be equal
176     if ( ! this.getName().equals(other.getName()) ) {
177         return false;
178     }
179 
180     // their Signatures should be equal
181     if ( ! Arrays.equals(this.getSignature(), other.getSignature()) ) {
182         return false;
183     }
184        
185     // their return open types should be equal
186     if ( ! this.getReturnOpenType().equals(other.getReturnOpenType()) ) {
187         return false;
188     }
189 
190     // their impacts should be equal
191     if ( this.getImpact() != other.getImpact() ) {
192         return false;
193     }
194 
195     // All tests for equality were successfull
196     //
197     return true;
198     }
199 
200     /**
201      * Returns the hash code value for this <code>OpenMBeanOperationInfoSupport</code> instance. 
202      * <p>
203      * The hash code of an <code>OpenMBeanOperationInfoSupport</code> instance is the sum of the hash codes
204      * of all elements of information used in <code>equals</code> comparisons 
205      * (ie: its name, return open type, impact and signature, where the signature hashCode is calculated by a call to 
206      *  <tt>java.util.Arrays.asList(this.getSignature).hashCode()</tt>). 
207      * <p>
208      * This ensures that <code> t1.equals(t2) </code> implies that <code> t1.hashCode()==t2.hashCode() </code> 
209      * for any two <code>OpenMBeanOperationInfoSupport</code> instances <code>t1</code> and <code>t2</code>, 
210      * as required by the general contract of the method
211      * {@link Object#hashCode() Object.hashCode()}.
212      * <p>
213      * However, note that another instance of a class implementing the <code>OpenMBeanOperationInfo</code> interface
214      * may be equal to this <code>OpenMBeanOperationInfoSupport</code> instance as defined by {@link #equals(java.lang.Object)}, 
215      * but may have a different hash code if it is calculated differently.
216      * <p>
217      * As <code>OpenMBeanOperationInfoSupport</code> instances are immutable, the hash code for this instance is calculated once,
218      * on the first call to <code>hashCode</code>, and then the same value is returned for subsequent calls.
219      *
220      * @return  the hash code value for this <code>OpenMBeanOperationInfoSupport</code> instance
221      */
222     public int hashCode() {
223 
224     // Calculate the hash code value if it has not yet been done (ie 1st call to hashCode())
225     //
226     if (myHashCode == null) {
227         int value = 0;
228         value += this.getName().hashCode();
229         value += Arrays.asList(this.getSignature()).hashCode();
230         value += this.getReturnOpenType().hashCode();
231         value += this.getImpact();
232         myHashCode = new Integer  (value);
233     }
234     
235     // return always the same hash code for this instance (immutable)
236     //
237     return myHashCode.intValue();
238     }
239 
240     /**
241      * Returns a string representation of this <code>OpenMBeanOperationInfoSupport</code> instance. 
242      * <p>
243      * The string representation consists of the name of this class (ie <code>javax.management.openmbean.OpenMBeanOperationInfoSupport</code>), 
244      * and the name, signature, return open type and impact of the described operation.
245      * <p>
246      * As <code>OpenMBeanOperationInfoSupport</code> instances are immutable, 
247      * the string representation for this instance is calculated once,
248      * on the first call to <code>toString</code>, and then the same value is returned for subsequent calls.
249      * 
250      * @return  a string representation of this <code>OpenMBeanOperationInfoSupport</code> instance
251      */
252     public String   toString() { 
253 
254     // Calculate the hash code value if it has not yet been done (ie 1st call to toString())
255     //
256     if (myToString == null) {
257         myToString = new StringBuffer  ()
258         .append(this.getClass().getName())
259         .append("(name=")
260         .append(this.getName())
261         .append(",signature=")
262         .append(Arrays.asList(this.getSignature()).toString())
263         .append(",return=")
264         .append(this.getReturnOpenType().toString())
265         .append(",impact=")
266         .append(this.getImpact())
267         .append(")")
268         .toString();
269     }
270 
271     // return always the same string representation for this instance (immutable)
272     //
273     return myToString;
274     }
275 
276 }
277
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