Source for javax.management.MBeanServerFactory

   1: /* MBeanServerFactory.java -- Manages server instances.
   2:    Copyright (C) 2006 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: package javax.management;
  39: 
  40: import gnu.classpath.SystemProperties;
  41: 
  42: import java.util.ArrayList;
  43: import java.util.HashMap;
  44: import java.util.Iterator;
  45: import java.util.Map;
  46: 
  47: import javax.management.loading.ClassLoaderRepository;
  48: 
  49: /**
  50:  * <p>
  51:  * Creates and maintains a set of {@link MBeanServer} instances.
  52:  * Server instances, as of JMX 1.2, are created using a subclass
  53:  * of {@link MBeanServerBuilder}.  The exact class used is controlled
  54:  * by the property <code>javax.management.builder.initial</code>,
  55:  * and allows the instances created by {@link MBeanServerBuilder}
  56:  * to be wrapped, thus providing additional functionality.
  57:  * </p>
  58:  * <p>
  59:  * The property is used as follows:
  60:  * </p>
  61:  * <ol>
  62:  * <li>If the property has no value, then an instance of
  63:  * {@link MBeanServerBuilder} is used.</li>
  64:  * <li>If a value is given, then:
  65:  * <ol>
  66:  * <li>The class is loaded using
  67:  * <code>Thread.currentThread().getContextClassLoader()</code>, or,
  68:  * if this is <code>null</code>, by <code>Class.forName()</code>.</li>
  69:  * <li><code>Class.newInstance()</code> is used to create an instance
  70:  * of the class.  The class must be public and have a public empty
  71:  * constructor.  If an exception is thrown, it is propogated as
  72:  * a {@link JMRuntimeException} and no new server instances may be
  73:  * created until the property is set to a valid value.</li>
  74:  * </ol></li>
  75:  * <li>The value is checked on each successive request for a server.
  76:  * If it differs from the class of the existing instance of
  77:  * {@link MBeanServerBuilder}, then the value is used to create
  78:  * a new instance.</li>
  79:  * </ol>
  80:  */
  81: public class MBeanServerFactory
  82: {
  83: 
  84:   /**
  85:    * The last builder instance.
  86:    */
  87:   private static MBeanServerBuilder builder;
  88: 
  89:   /**
  90:    * The map of registered servers (identifiers to servers).
  91:    */
  92:   private static final Map<Object,MBeanServer> servers =
  93:     new HashMap<Object,MBeanServer>();
  94: 
  95:   /**
  96:    * Private constructor to prevent instance creation.
  97:    */
  98:   private MBeanServerFactory() {}
  99: 
 100:   /**
 101:    * Returns a server implementation using the default domain name
 102:    * of <code>"DefaultDomain"</code>.  The default domain name is
 103:    * used when the domain name specified by the user is <code>null</code.
 104:    * A reference to the created server is retained, so that it can
 105:    * be retrieved at a later date using {@link #findMBeanServer}.
 106:    * Calling this method is equivalent to calling
 107:    * {@link createMBeanServer(String)} with a <code>null</code> value.
 108:    *
 109:    * @return a new {@link MBeanServer} instance.
 110:    * @throws SecurityException if a security manager exists and the
 111:    *                           caller's permissions don't imply {@link
 112:    *                           MBeanServerPermission(String)}("createMBeanServer")
 113:    * @throws JMRuntimeException if the property
 114:    *                     <code>javax.management.builder.initial</code>
 115:    *                     exists but names a class which either can not be
 116:    *                     instantiated or provides an implementation that returns
 117:    *                     <code>null</code> from either
 118:    *                     {@link MBeanServerBuilder#newMBeanServerDelegate()}
 119:    *                     or {@link MBeanServerBuilder#newMBeanServer()}
 120:    * @throws ClassCastException if the property
 121:    *                     <code>javax.management.builder.initial</code>
 122:    *                     exists but names a class which is not a subclass
 123:    *                     of {@link MBeanServerBuilder}.
 124:    * @see #createMBeanServer(String)
 125:    */
 126:   public static MBeanServer createMBeanServer()
 127:   {
 128:     return createMBeanServer(null);
 129:   }
 130: 
 131:   /**
 132:    * Returns a server implementation using the default domain name
 133:    * given, or <code>"DefaultDomain"</code> if this is <code>null</code>.
 134:    * The default domain name is used when the domain name specified by
 135:    * the user is <code>null</code.  A reference to the created server is
 136:    * retained, so that it can be retrieved at a later date using
 137:    * {@link #findMBeanServer}.
 138:    *
 139:    * @param domain the default domain name of the server.
 140:    * @return a new {@link MBeanServer} instance.
 141:    * @throws SecurityException if a security manager exists and the
 142:    *                           caller's permissions don't imply {@link
 143:    *                           MBeanServerPermission(String)}("createMBeanServer")
 144:    * @throws JMRuntimeException if the property
 145:    *                     <code>javax.management.builder.initial</code>
 146:    *                     exists but names a class which either can not be
 147:    *                     instantiated or provides an implementation that returns
 148:    *                     <code>null</code> from either
 149:    *                     {@link MBeanServerBuilder#newMBeanServerDelegate()}
 150:    *                     or {@link MBeanServerBuilder#newMBeanServer()}
 151:    * @throws ClassCastException if the property
 152:    *                     <code>javax.management.builder.initial</code>
 153:    *                     exists but names a class which is not a subclass
 154:    *                     of {@link MBeanServerBuilder}.
 155:    */
 156:   public static MBeanServer createMBeanServer(String domain)
 157:   {
 158:     SecurityManager sm = System.getSecurityManager();
 159:     if (sm != null)
 160:       sm.checkPermission(new MBeanServerPermission("createMBeanServer"));
 161:     MBeanServer server = createServer(domain);
 162:     try
 163:       {
 164:         ObjectName dn = new
 165:           ObjectName("JMImplementation:type=MBeanServerDelegate");
 166:         servers.put(server.getAttribute(dn, "MBeanServerId"), server);
 167:       }
 168:     catch (MalformedObjectNameException e)
 169:       {
 170:         throw (Error)
 171:           (new InternalError("Malformed delegate bean name.").initCause(e));
 172:       }
 173:     catch (MBeanException e)
 174:       {
 175:         throw (Error)
 176:           (new InternalError("Exception in getMBeanServerId().").initCause(e));
 177:       }
 178:     catch (AttributeNotFoundException e)
 179:       {
 180:         throw (Error)
 181:           (new InternalError("Could not find MBeanServerId attribute.").initCause(e));
 182:       }
 183:     catch (InstanceNotFoundException e)
 184:       {
 185:         throw (Error)
 186:           (new InternalError("Could not find the delegate bean.").initCause(e));
 187:       }
 188:     catch (ReflectionException e)
 189:       {
 190:         throw (Error)
 191:           (new InternalError("Could not call getMBeanServerId().").initCause(e));
 192:       }
 193:     return server;
 194:   }
 195: 
 196:   /**
 197:    * Returns the specified server, or, if <code>id</code> is <code>null</code>,
 198:    * a list of all registered servers.  A registered server is one that
 199:    * was created using {@link #createMBeanServer()} or
 200:    * {@link #createMBeanServer(String)} and has not yet been released
 201:    * using {@link releaseMBeanServer(MBeanServer)}.
 202:    *
 203:    * @param id the id of the server to retrieve, or <code>null</code>
 204:    *           to return all servers.
 205:    * @return a list of {@link MBeanServer}s.
 206:    * @throws SecurityException if a security manager exists and the
 207:    *                           caller's permissions don't imply {@link
 208:    *                           MBeanServerPermission(String)}("findMBeanServer")
 209:    */
 210:   public static ArrayList<MBeanServer> findMBeanServer(String id)
 211:   {
 212:     SecurityManager sm = System.getSecurityManager();
 213:     if (sm != null)
 214:       sm.checkPermission(new MBeanServerPermission("findMBeanServer"));
 215:     if (id == null)
 216:       return new ArrayList<MBeanServer>(servers.values());
 217:     ArrayList<MBeanServer> list = new ArrayList<MBeanServer>();
 218:     MBeanServer server = servers.get(id);
 219:     if (server != null)
 220:       list.add(servers.get(id));
 221:     return list;
 222:   }
 223: 
 224:   /**
 225:    * Returns the class loader repository used by the specified server.
 226:    * This is equivalent to calling {@link MBeanServer#getClassLoaderRepository()}
 227:    * on the given server.
 228:    *
 229:    * @param server the server whose class loader repository should be
 230:    *               retrieved.
 231:    * @throws NullPointerException if <code>server</code> is <code>null</code>.
 232:    * @throws SecurityException if a security manager exists and the
 233:    *                           caller's permissions don't imply {@link
 234:    *                           MBeanPermission(String,String,ObjectName,String)
 235:    *                           <code>MBeanPermission(null, null, null,
 236:    *                           "getClassLoaderRepository")</code>
 237:    */
 238:   public static ClassLoaderRepository getClassLoaderRepository(MBeanServer server)
 239:   {
 240:     return server.getClassLoaderRepository();
 241:   }
 242: 
 243:   /**
 244:    * Returns a server implementation using the default domain name
 245:    * of <code>"DefaultDomain"</code>.  The default domain name is
 246:    * used when the domain name specified by the user is <code>null</code.
 247:    * No reference to the created server is retained, so the server is
 248:    * garbage collected when it is no longer used, but it can not be
 249:    * retrieved at a later date using {@link #findMBeanServer}.
 250:    * Calling this method is equivalent to calling
 251:    * {@link newMBeanServer(String)} with a <code>null</code> value.
 252:    *
 253:    * @return a new {@link MBeanServer} instance.
 254:    * @throws SecurityException if a security manager exists and the
 255:    *                           caller's permissions don't imply {@link
 256:    *                           MBeanServerPermission(String)}("newMBeanServer")
 257:    * @throws JMRuntimeException if the property
 258:    *                     <code>javax.management.builder.initial</code>
 259:    *                     exists but names a class which either can not be
 260:    *                     instantiated or provides an implementation that returns
 261:    *                     <code>null</code> from either
 262:    *                     {@link MBeanServerBuilder#newMBeanServerDelegate()}
 263:    *                     or {@link MBeanServerBuilder#newMBeanServer()}
 264:    * @throws ClassCastException if the property
 265:    *                     <code>javax.management.builder.initial</code>
 266:    *                     exists but names a class which is not a subclass
 267:    *                     of {@link MBeanServerBuilder}.
 268:    * @see #newMBeanServer(String)
 269:    */
 270:   public static MBeanServer newMBeanServer()
 271:   {
 272:     return newMBeanServer(null);
 273:   }
 274: 
 275:   /**
 276:    * Returns a server implementation using the default domain name
 277:    * given, or <code>"DefaultDomain"</code> if this is <code>null</code>.
 278:    * The default domain name is used when the domain name specified by
 279:    * the user is <code>null</code.  No reference to the created server is
 280:    * retained, so the server is garbage collected when it is no longer
 281:    * used, but it can not be retrieved at a later date using
 282:    * {@link #findMBeanServer}.
 283:    *
 284:    * @param domain the default domain name of the server.
 285:    * @return a new {@link MBeanServer} instance.
 286:    * @throws SecurityException if a security manager exists and the
 287:    *                           caller's permissions don't imply {@link
 288:    *                           MBeanServerPermission(String)}("newMBeanServer")
 289:    * @throws JMRuntimeException if the property
 290:    *                     <code>javax.management.builder.initial</code>
 291:    *                     exists but names a class which either can not be
 292:    *                     instantiated or provides an implementation that returns
 293:    *                     <code>null</code> from either
 294:    *                     {@link MBeanServerBuilder#newMBeanServerDelegate()}
 295:    *                     or {@link MBeanServerBuilder#newMBeanServer()}
 296:    * @throws ClassCastException if the property
 297:    *                     <code>javax.management.builder.initial</code>
 298:    *                     exists but names a class which is not a subclass
 299:    *                     of {@link MBeanServerBuilder}.
 300:    */
 301:   public static MBeanServer newMBeanServer(String domain)
 302:   {
 303:     SecurityManager sm = System.getSecurityManager();
 304:     if (sm != null)
 305:       sm.checkPermission(new MBeanServerPermission("newMBeanServer"));
 306:     return createServer(domain);
 307:   }
 308: 
 309:   /**
 310:    * Common method to create a server for the {@link #createMBeanServer(String)}
 311:    * and {@link #newMBeanServer(String)} methods above.
 312:    *
 313:    * @param domain the default domain name of the server.
 314:    * @throws JMRuntimeException if the property
 315:    *                     <code>javax.management.builder.initial</code>
 316:    *                     exists but names a class which either can not be
 317:    *                     instantiated or provides an implementation that returns
 318:    *                     <code>null</code> from either
 319:    *                     {@link MBeanServerBuilder#newMBeanServerDelegate()}
 320:    *                     or {@link MBeanServerBuilder#newMBeanServer()}
 321:    * @throws ClassCastException if the property
 322:    *                     <code>javax.management.builder.initial</code>
 323:    *                     exists but names a class which is not a subclass
 324:    *                     of {@link MBeanServerBuilder}.
 325:    */
 326:   private static MBeanServer createServer(String domain)
 327:     {
 328:     if (domain == null)
 329:       domain = "DefaultDomain";
 330:     String builderClass =
 331:       SystemProperties.getProperty("javax.management.builder.initial");
 332:     if (builderClass == null)
 333:       {
 334:         if (builder == null ||
 335:             builder.getClass() != MBeanServerBuilder.class)
 336:           builder = new MBeanServerBuilder();
 337:       }
 338:     else if (!(builder != null &&
 339:                builderClass.equals(builder.getClass().getName())))
 340:       {
 341:         ClassLoader cl = Thread.currentThread().getContextClassLoader();
 342:         if (cl == null)
 343:           cl = MBeanServerFactory.class.getClassLoader();
 344:         try
 345:           {
 346:             Class<?> bClass = Class.forName(builderClass, true, cl);
 347:             builder = (MBeanServerBuilder) bClass.newInstance();
 348:           }
 349:         catch (ClassNotFoundException e)
 350:           {
 351:             throw (JMRuntimeException) (new JMRuntimeException("The builder class, "
 352:                                                                + builderClass +
 353:                                                                ", could not be found."))
 354:               .initCause(e);
 355:           }
 356:         catch (InstantiationException e)
 357:           {
 358:             throw (JMRuntimeException) (new JMRuntimeException("The builder class, "
 359:                                                                + builderClass +
 360:                                                                ", could not be instantiated."))
 361:               .initCause(e);
 362:           }
 363:         catch (IllegalAccessException e)
 364:           {
 365:             throw (JMRuntimeException) (new JMRuntimeException("The builder class, "
 366:                                                                + builderClass +
 367:                                                                ", could not be accessed."))
 368:               .initCause(e);
 369:           }
 370:       }
 371:     MBeanServerDelegate delegate = builder.newMBeanServerDelegate();
 372:     if (delegate == null)
 373:       throw new JMRuntimeException("A delegate could not be created.");
 374:     MBeanServer server = builder.newMBeanServer(domain, null, delegate);
 375:     if (server == null)
 376:       throw new JMRuntimeException("A server could not be created.");
 377:     return server;
 378:   }
 379: 
 380:   /**
 381:    * Removes the reference to the specified server, thus allowing it to
 382:    * be garbage collected.
 383:    *
 384:    * @param server the server to remove.
 385:    * @throws IllegalArgumentException if a reference to the server is not
 386:    *                                  held (i.e. it wasn't created by
 387:    *                                  {@link #createMBeanServer(String)}
 388:    *                                  or this method has already been called
 389:    *                                  on it.
 390:    * @throws SecurityException if a security manager exists and the
 391:    *                           caller's permissions don't imply {@link
 392:    *                           MBeanServerPermission(String)}("releaseMBeanServer")
 393:    */
 394:   public static void releaseMBeanServer(MBeanServer server)
 395:   {
 396:     SecurityManager sm = System.getSecurityManager();
 397:     if (sm != null)
 398:       sm.checkPermission(new MBeanServerPermission("releaseMBeanServer"));
 399:     Iterator<MBeanServer> i = servers.values().iterator();
 400:     while (i.hasNext())
 401:       {
 402:         MBeanServer s = i.next();
 403:         if (server == s)
 404:           {
 405:             i.remove();
 406:             return;
 407:           }
 408:       }
 409:     throw new IllegalArgumentException("The server given is not referenced.");
 410:   }
 411: 
 412: 
 413: }