MBeanServerFactoryBean returns JDK 1.5 platform MBeanServer for agent id "" (SPR-5909)

org.springframework.context/src/main/java/org/springframework/jmx/access/MBeanClientInterceptor.java

@@ -161,6 +161,7 @@ public class MBeanClientInterceptor
 	 * attempt being made to locate the attendant MBeanServer, unless
 	 * the {@link #setServiceUrl "serviceUrl"} property has been set.
 	 * @see javax.management.MBeanServerFactory#findMBeanServer(String)
+	 * <p>Specifying the empty String indicates the platform MBeanServer.
 	 */
 	public void setAgentId(String agentId) {
 		this.agentId = agentId;

org.springframework.context/src/main/java/org/springframework/jmx/access/NotificationListenerRegistrar.java

 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2009 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -105,6 +105,7 @@ public class NotificationListenerRegistrar extends NotificationListenerHolder
 	 * attempt being made to locate the attendant MBeanServer, unless
 	 * the {@link #setServiceUrl "serviceUrl"} property has been set.
 	 * @see javax.management.MBeanServerFactory#findMBeanServer(String)
+	 * <p>Specifying the empty String indicates the platform MBeanServer.
 	 */
 	public void setAgentId(String agentId) {
 		this.agentId = agentId;

org.springframework.context/src/main/java/org/springframework/jmx/support/JmxUtils.java

@@ -91,28 +91,31 @@ public abstract class JmxUtils {
 	 * <code>MBeanServer</code> can be found. Logs a warning if more than one
 	 * <code>MBeanServer</code> found, returning the first one from the list.
 	 * @param agentId the agent identifier of the MBeanServer to retrieve.
-	 * If this parameter is <code>null</code>, all registered MBeanServers are
-	 * considered.
+	 * If this parameter is <code>null</code>, all registered MBeanServers are considered.
+	 * If the empty String is given, the platform MBeanServer will be returned.
 	 * @return the <code>MBeanServer</code> if found
 	 * @throws org.springframework.jmx.MBeanServerNotFoundException
 	 * if no <code>MBeanServer</code> could be found
 	 * @see javax.management.MBeanServerFactory#findMBeanServer(String)
 	 */
 	public static MBeanServer locateMBeanServer(String agentId) throws MBeanServerNotFoundException {
-		List servers = MBeanServerFactory.findMBeanServer(agentId);
-
 		MBeanServer server = null;
-		if (servers != null && servers.size() > 0) {
-			// Check to see if an MBeanServer is registered.
-			if (servers.size() > 1 && logger.isWarnEnabled()) {
-				logger.warn("Found more than one MBeanServer instance" +
-						(agentId != null ? " with agent id [" + agentId + "]" : "") +
-						". Returning first from list.");
+
+		// null means any registered server, but "" specifically means the platform server
+		if (!"".equals(agentId)) {
+			List<MBeanServer> servers = MBeanServerFactory.findMBeanServer(agentId);
+			if (servers != null && servers.size() > 0) {
+				// Check to see if an MBeanServer is registered.
+				if (servers.size() > 1 && logger.isWarnEnabled()) {
+					logger.warn("Found more than one MBeanServer instance" +
+							(agentId != null ? " with agent id [" + agentId + "]" : "") +
+							". Returning first from list.");
+				}
+				server = servers.get(0);
 			}
-			server = (MBeanServer) servers.get(0);
 		}
 
-		if (server == null && agentId == null) {
+		if (server == null && !StringUtils.hasLength(agentId)) {
 			// Attempt to load the PlatformMBeanServer.
 			try {
 				server = ManagementFactory.getPlatformMBeanServer();

org.springframework.context/src/main/java/org/springframework/jmx/support/MBeanServerFactoryBean.java

@@ -84,6 +84,7 @@ public class MBeanServerFactoryBean implements FactoryBean<MBeanServer>, Initial
 	 * and (importantly) if said MBeanServer cannot be located no
 	 * attempt will be made to create a new MBeanServer (and an
 	 * MBeanServerNotFoundException will be thrown at resolution time).
+	 * <p>Specifying the empty String indicates the platform MBeanServer.
 	 * @see javax.management.MBeanServerFactory#findMBeanServer(String)
 	 */
 	public void setAgentId(String agentId) {

org.springframework.context/src/test/java/org/springframework/jmx/support/MBeanServerFactoryBeanTests.java

 /*
- * Copyright 2002-2005 the original author or authors.
+ * Copyright 2002-2009 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
  *
- * http://www.apache.org/licenses/LICENSE-2.0
+ *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
@@ -17,7 +17,7 @@
 package org.springframework.jmx.support;
 
 import java.util.List;
-
+import java.lang.management.ManagementFactory;
 import javax.management.MBeanServer;
 import javax.management.MBeanServerFactory;
 
@@ -25,6 +25,7 @@ import junit.framework.TestCase;
 
 /**
  * @author Rob Harrop
+ * @author Juergen Hoeller
  */
 public class MBeanServerFactoryBeanTests extends TestCase {
 
@@ -32,7 +33,7 @@ public class MBeanServerFactoryBeanTests extends TestCase {
 		MBeanServerFactoryBean bean = new MBeanServerFactoryBean();
 		bean.afterPropertiesSet();
 		try {
-			MBeanServer server = (MBeanServer) bean.getObject();
+			MBeanServer server = bean.getObject();
 			assertNotNull("The MBeanServer should not be null", server);
 		}
 		finally {
@@ -45,7 +46,7 @@ public class MBeanServerFactoryBeanTests extends TestCase {
 		bean.setDefaultDomain("foo");
 		bean.afterPropertiesSet();
 		try {
-			MBeanServer server = (MBeanServer) bean.getObject();
+			MBeanServer server = bean.getObject();
 			assertEquals("The default domain should be foo", "foo", server.getDefaultDomain());
 		}
 		finally {
@@ -60,7 +61,7 @@ public class MBeanServerFactoryBeanTests extends TestCase {
 			bean.setLocateExistingServerIfPossible(true);
 			bean.afterPropertiesSet();
 			try {
-				MBeanServer otherServer = (MBeanServer) bean.getObject();
+				MBeanServer otherServer = bean.getObject();
 				assertSame("Existing MBeanServer not located", server, otherServer);
 			}
 			finally {
@@ -72,12 +73,24 @@ public class MBeanServerFactoryBeanTests extends TestCase {
 		}
 	}
 
-	public void testWithLocateExistingAndNoExistingServer() {
+	public void testWithLocateExistingAndFallbackToPlatformServer() {
 		MBeanServerFactoryBean bean = new MBeanServerFactoryBean();
 		bean.setLocateExistingServerIfPossible(true);
 		bean.afterPropertiesSet();
 		try {
-			assertNotNull("MBeanServer not created", bean.getObject());
+			assertSame(ManagementFactory.getPlatformMBeanServer(), bean.getObject());
+		}
+		finally {
+			bean.destroy();
+		}
+	}
+
+	public void testWithEmptyAgentIdAndFallbackToPlatformServer() {
+		MBeanServerFactoryBean bean = new MBeanServerFactoryBean();
+		bean.setAgentId("");
+		bean.afterPropertiesSet();
+		try {
+			assertSame(ManagementFactory.getPlatformMBeanServer(), bean.getObject());
 		}
 		finally {
 			bean.destroy();
@@ -98,12 +111,12 @@ public class MBeanServerFactoryBeanTests extends TestCase {
 		bean.afterPropertiesSet();
 
 		try {
-			MBeanServer server = (MBeanServer) bean.getObject();
-			List servers = MBeanServerFactory.findMBeanServer(null);
+			MBeanServer server = bean.getObject();
+			List<MBeanServer> servers = MBeanServerFactory.findMBeanServer(null);
 
 			boolean found = false;
-			for (int x = 0; x < servers.size(); x++) {
-				if (servers.get(x) == server) {
+			for (MBeanServer candidate : servers) {
+				if (candidate == server) {
 					found = true;
 					break;
 				}