ActivationGroupDesc


1   /*
2    * @(#)ActivationGroupDesc.java 1.28 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   package java.rmi.activation;
9   
10  import java.io.IOException  ;
11  import java.rmi.MarshalledObject  ;
12  import java.util.Arrays  ;
13  import java.util.ArrayList  ;
14  import java.util.Collection  ;
15  import java.util.Collections  ;
16  import java.util.Iterator  ;
17  import java.util.List  ;
18  import java.util.Properties  ;
19  
20  
21  /**
22   * An activation group descriptor contains the information necessary to
23   * create/recreate an activation group in which to activate objects.
24   * Such a descriptor contains: <ul>
25   * <li> the group's class name,
26   * <li> the group's code location (the location of the group's class), and
27   * <li> a "marshalled" object that can contain group specific
28   * initialization data. </ul> <p>
29   *
30   * The group's class must be a concrete subclass of
31   * <code>ActivationGroup</code>. A subclass of
32   * <code>ActivationGroup</code> is created/recreated via the
33   * <code>ActivationGroup.createGroup</code> static method that invokes
34   * a special constructor that takes two arguments: <ul>
35   *
36   * <li> the group's <code>ActivationGroupID</code>, and
37   * <li> the group's initialization data (in a
38   * <code>java.rmi.MarshalledObject</code>)</ul><p>
39   *
40   * @version 1.28, 12/19/03
41   * @author  Ann Wollrath
42   * @since   1.2
43   * @see     ActivationGroup
44   * @see     ActivationGroupID
45   */
46  public final class ActivationGroupDesc implements java.io.Serializable   {
47  
48      /**
49       * @serial The group's fully package qualified class name.
50       */
51      private String   className;
52  
53      /**
54       * @serial The location from where to load the group's class.
55       */
56      private String   location;
57  
58      /**
59       * @serial The group's initialization data.
60       */
61      private MarshalledObject   data;
62  
63      /**
64       * @serial The controlling options for executing the VM in
65       * another process.
66       */
67      private CommandEnvironment env;
68      
69      /**
70       * @serial A properties map which will override those set
71       * by default in the subprocess environment.
72       */
73      private Properties   props;
74      
75      /** indicate compatibility with the Java 2 SDK v1.2 version of class */
76      private static final long serialVersionUID = -4936225423168276595L;
77  
78      /**
79       * Constructs a group descriptor that uses the system defaults for group
80       * implementation and code location.  Properties specify Java
81       * environment overrides (which will override system properties in
82       * the group implementation's VM).  The command
83       * environment can control the exact command/options used in
84       * starting the child VM, or can be <code>null</code> to accept
85       * rmid's default.
86       *
87       * <p>This constructor will create an <code>ActivationGroupDesc</code>
88       * with a <code>null</code> group class name, which indicates the system's
89       * default <code>ActivationGroup</code> implementation.
90       *
91       * @param overrides the set of properties to set when the group is
92       * recreated.
93       * @param cmd the controlling options for executing the VM in
94       * another process (or <code>null</code>).
95       * @since 1.2
96       */
97      public ActivationGroupDesc(Properties   overrides,
98                                 CommandEnvironment cmd)
99      {
100     this(null, null, null, overrides, cmd);
101     }
102 
103     /**
104      * Specifies an alternate group implementation and execution
105      * environment to be used for the group.
106      * 
107      * @param className the group's package qualified class name or
108      * <code>null</code>. A <code>null</code> group class name indicates
109      * the system's default <code>ActivationGroup</code> implementation.
110      * @param location the location from where to load the group's
111      * class
112      * @param data the group's initialization data contained in
113      * marshalled form (could contain properties, for example)
114      * @param overrides a properties map which will override those set
115      * by default in the subprocess environment (will be translated
116      * into <code>-D</code> options), or <code>null</code>.
117      * @param cmd the controlling options for executing the VM in
118      * another process (or <code>null</code>).
119      * @since 1.2
120      */
121     public ActivationGroupDesc(String   className,
122                    String   location,
123                    MarshalledObject   data,
124                    Properties   overrides,
125                                CommandEnvironment cmd)
126     {
127     this.props = overrides;
128     this.env = cmd;
129     this.data = data;
130     this.location = location;
131     this.className = className;
132     }
133 
134     /**
135      * Returns the group's class name (possibly <code>null</code>).  A
136      * <code>null</code> group class name indicates the system's default
137      * <code>ActivationGroup</code> implementation.
138      * @return the group's class name
139      * @since 1.2
140      */
141     public String   getClassName() {
142     return className;
143     }
144 
145     /**
146      * Returns the group's code location.
147      * @return the group's code location
148      * @since 1.2
149      */
150     public String   getLocation() {
151     return location;
152     }
153 
154     /**
155      * Returns the group's initialization data.
156      * @return the group's initialization data
157      * @since 1.2
158      */
159     public MarshalledObject   getData() {
160     return data;
161     }
162 
163     /**
164      * Returns the group's property-override list.
165      * @return the property-override list, or <code>null</code>
166      * @since 1.2
167      */
168     public Properties   getPropertyOverrides() {
169     return (props != null) ? (Properties  ) props.clone() : null;
170     }
171 
172     /**
173      * Returns the group's command-environment control object.
174      * @return the command-environment object, or <code>null</code>
175      * @since 1.2
176      */
177     public CommandEnvironment getCommandEnvironment() {
178     return this.env;
179     }
180 
181 
182     /**
183      * Startup options for ActivationGroup implementations.
184      *
185      * This class allows overriding default system properties and
186      * specifying implementation-defined options for ActivationGroups.
187      * @since 1.2
188      */
189     public static class CommandEnvironment
190     implements java.io.Serializable  
191     {
192     private static final long serialVersionUID = 6165754737887770191L;
193 
194     /**
195      * @serial
196      */
197     private String   command;
198 
199     /**
200      * @serial
201      */
202     private String  [] options;
203 
204     /**
205      * Create a CommandEnvironment with all the necessary
206      * information.
207      * 
208      * @param cmdpath the name of the java executable, including
209      * the full path, or <code>null</code>, meaning "use rmid's default".
210      * The named program <em>must</em> be able to accept multiple
211      * <code>-Dpropname=value</code> options (as documented for the
212      * "java" tool)
213      * 
214      * @param argv extra options which will be used in creating the
215      * ActivationGroup.  Null has the same effect as an empty
216      * list.
217      * @since 1.2
218      */
219     public CommandEnvironment(String   cmdpath,
220                   String  [] argv)
221     {
222         this.command = cmdpath; // might be null
223 
224         // Hold a safe copy of argv in this.options
225         if (argv == null) {
226         this.options = null;
227         } else {
228         this.options = new String  [argv.length];
229         System.arraycopy(argv, 0, this.options, 0, argv.length);
230         }
231     }
232 
233     /**
234      * Fetch the configured path-qualified java command name.
235      *
236      * @return the configured name, or <code>null</code> if configured to
237      * accept the default
238      * @since 1.2
239      */
240     public String   getCommandPath() {
241         return (this.command);
242     }
243 
244     /**
245      * Fetch the configured java command options.
246      *
247      * @return An array of the command options which will be passed
248      * to the new child command by rmid.
249      * Note that rmid may add other options before or after these
250      * options, or both.
251      * Never returns <code>null</code>.
252      * @since 1.2
253      */
254     public String  [] getCommandOptions() {
255         return (this.options != null
256             ? (String  []) this.options.clone()
257             : new String  [0]);
258     }
259     
260     /**
261      * Compares two command environments for content equality.
262      *
263      * @param   obj the Object to compare with
264      * @return  true if these Objects are equal; false otherwise.
265      * @see     java.util.Hashtable
266      * @since 1.2
267      */
268     public boolean equals(Object   obj) {
269     
270         if (obj instanceof CommandEnvironment) {
271         CommandEnvironment env = (CommandEnvironment) obj;
272         return
273             ((command == null ? env.command == null :
274               command.equals(env.command)) &&
275              Arrays.equals(options, env.options));
276         } else {
277         return false;
278         }
279     }
280 
281     /**
282      * Return identical values for similar
283      * <code>CommandEnvironment</code>s.
284      * @return an integer
285      * @see java.util.Hashtable
286      */
287     public int hashCode()
288     {
289         // hash command and ignore possibly expensive options
290         return (command == null ? 0 : command.hashCode());
291     }
292     }
293 
294     /**
295      * Compares two activation group descriptors for content equality.
296      *
297      * @param   obj the Object to compare with
298      * @return  true if these Objects are equal; false otherwise.
299      * @see     java.util.Hashtable
300      * @since 1.2
301      */
302     public boolean equals(Object   obj) {
303     
304     if (obj instanceof ActivationGroupDesc  ) {
305         ActivationGroupDesc   desc = (ActivationGroupDesc  ) obj;
306         return
307         ((className == null ? desc.className == null :
308           className.equals(desc.className)) &&
309          (location == null ? desc.location == null :
310           location.equals(desc.location)) &&
311          (data == null ? desc.data == null : data.equals(desc.data)) &&
312          (env == null ? desc.env == null : env.equals(desc.env)) &&
313          (props == null ? desc.props == null :
314           props.equals(desc.props)));
315     } else {
316         return false;
317     }
318     }
319 
320     /**
321      * Produce identical numbers for similar <code>ActivationGroupDesc</code>s.
322      * @return an integer
323      * @see java.util.Hashtable
324      */
325     public int hashCode()
326     {
327     // hash location, className, data, and env
328     // but omit props (may be expensive)
329     return ((location == null
330             ? 0
331             : location.hashCode() << 24) ^
332         (env == null
333             ? 0
334             : env.hashCode() << 16) ^
335         (className == null
336             ? 0
337             : className.hashCode() << 8) ^
338         (data == null
339             ? 0
340             : data.hashCode()));
341     }
342     
343 }
344 
345
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