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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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 or visit www.oracle.com if you need additional information or have any 23 questions. 24 --> 25 26 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> 27 <html> 28 <body bgcolor="white"> 29 30 Provides the management interfaces for monitoring and management of the 31 Java virtual machine and other components in the Java runtime. 32 It allows both local and remote 33 monitoring and management of the running Java virtual machine. 34 35 <h4><a name="MXBean">Platform MXBean</a></h4> 36 <p> 37 A platform MXBean is a <i>managed bean</i> that 38 conforms to the <a href="../../../javax/management/package-summary.html">JMX</a> 39 Instrumentation Specification and only uses a set of basic data types. 40 Each platform MXBean is a {@link java.lang.management.PlatformManagedObject} 41 with a unique 42 {@linkplain java.lang.management.PlatformManagedObject#getObjectName name}. 43 <h4>ManagementFactory</h4> 44 45 <p>The {@link java.lang.management.ManagementFactory} class is the management 46 factory class for the Java platform. This class provides a set of 47 static factory methods to obtain the MXBeans for the Java platform 48 to allow an application to access the MXBeans directly. 49 50 <p>A <em>platform MBeanServer</em> can be accessed with the 51 {@link java.lang.management.ManagementFactory#getPlatformMBeanServer 52 getPlatformMBeanServer} method. On the first call to this method, 53 it creates the platform MBeanServer and registers all platform MXBeans 54 including {@linkplain java.lang.management.PlatformManagedObject 55 platform MXBeans}. 56 Each platform MXBean is registered with a unique name defined in 57 the specification of the management interface. 58 This is a single MBeanServer that can be shared by different managed 59 components running within the same Java virtual machine. 60 61 <h4>Interoperability</h4> 62 63 <p>A management application and a platform MBeanServer of a running 64 virtual machine can interoperate 65 without requiring classes used by the platform MXBean interfaces. 66 The data types being transmitted between the JMX connector 67 server and the connector client are JMX 68 {@linkplain javax.management.openmbean.OpenType open types} and 69 this allows interoperation across versions. 70 A data type used by the MXBean interfaces are mapped to an 71 open type when being accessed via MBeanServer interface. 72 See the <a href="../../../javax/management/MXBean.html#MXBean-spec"> 73 MXBean</a> specification for details. 74 75 <h4><a name="examples">Ways to Access MXBeans</a></h4> 76 77 <p>An application can monitor the instrumentation of the 78 Java virtual machine and the runtime in the following ways: 79 <p> 80 <b>1. Direct access to an MXBean interface</b> 81 <ul> 82 <li>Get an MXBean instance locally in the running Java virtual machine: 83 <pre> 84 RuntimeMXBean mxbean = ManagementFactory.getRuntimeMXBean(); 85 86 // Get the standard attribute "VmVendor" 87 String vendor = mxbean.getVmVendor(); 88 </pre> 89 <p>Or by calling the 90 {@link java.lang.management.ManagementFactory#getPlatformMXBean(Class) 91 getPlatformMXBean} or 92 {@link java.lang.management.ManagementFactory#getPlatformMXBeans(Class) 93 getPlatformMXBeans} method: 94 <pre> 95 RuntimeMXBean mxbean = ManagementFactory.getPlatformMXBean(RuntimeMXBean.class); 96 97 // Get the standard attribute "VmVendor" 98 String vendor = mxbean.getVmVendor(); 99 </pre> 100 </li> 101 <li>Construct an MXBean proxy instance that forwards the 102 method calls to a given MBeanServer: 103 <pre> 104 MBeanServerConnection mbs; 105 106 // Connect to a running JVM (or itself) and get MBeanServerConnection 107 // that has the JVM MBeans registered in it 108 ... 109 110 // Get a MBean proxy for RuntimeMXBean interface 111 RuntimeMXBean proxy = 112 {@link java.lang.management.ManagementFactory#getPlatformMXBean(MBeanServerConnection, Class) 113 ManagementFactory.getPlatformMXBean}(mbs, 114 RuntimeMXBean.class); 115 // Get standard attribute "VmVendor" 116 String vendor = proxy.getVmVendor(); 117 </pre> 118 <p>A proxy is typically used to access an MXBean 119 in a remote Java virtual machine. 120 An alternative way to create an MXBean proxy is: 121 <pre> 122 RuntimeMXBean proxy = 123 {@link java.lang.management.ManagementFactory#newPlatformMXBeanProxy 124 ManagementFactory.newPlatformMXBeanProxy}(mbs, 125 ManagementFactory.RUNTIME_MXBEAN_NAME, 126 RuntimeMXBean.class); 127 </pre> 128 </li> 129 </ul> 130 <p> 131 <b>2. Indirect access to an MXBean interface via MBeanServer</b> 132 <ul> 133 <li>Go through the 134 {@link java.lang.management.ManagementFactory#getPlatformMBeanServer 135 platform MBeanServer} to access MXBeans locally or 136 a specific {@code MBeanServerConnection} to access 137 MXBeans remotely. 138 The attributes and operations of an MXBean use only 139 <em>JMX open types</em> which include basic data types, 140 {@link javax.management.openmbean.CompositeData CompositeData}, 141 and {@link javax.management.openmbean.TabularData TabularData} 142 defined in {@link javax.management.openmbean.OpenType OpenType}. 143 <pre> 144 MBeanServerConnection mbs; 145 146 // Connect to a running JVM (or itself) and get MBeanServerConnection 147 // that has the JVM MXBeans registered in it 148 ... 149 150 try { 151 // Assuming the RuntimeMXBean has been registered in mbs 152 ObjectName oname = new ObjectName(ManagementFactory.RUNTIME_MXBEAN_NAME); 153 154 // Get standard attribute "VmVendor" 155 String vendor = (String) mbs.getAttribute(oname, "VmVendor"); 156 } catch (....) { 157 // Catch the exceptions thrown by ObjectName constructor 158 // and MBeanServer.getAttribute method 159 ... 160 } 161 </pre> 162 </li> 163 </ul> 164 165 166 <h4><a name="extension">Platform Extension</a></h4> 167 168 <p>A Java virtual machine implementation may add its platform extension to 169 the management interface by defining platform-dependent 170 interfaces that extend the standard management interfaces to include 171 platform-specific metrics and management operations. 172 The static factory methods in the <tt>ManagementFactory</tt> class will 173 return the MXBeans with the platform extension. 174 175 <p> 176 It is recommended to name the platform-specific attributes with 177 a vendor-specific prefix such as the vendor's name to 178 avoid collisions of the attribute name between the future extension 179 to the standard management interface and the platform extension. 180 If the future extension to the standard management interface defines 181 a new attribute for a management interface and the attribute name 182 is happened to be same as some vendor-specific attribute's name, 183 the applications accessing that vendor-specific attribute would have 184 to be modified to cope with versioning and compatibility issues. 185 186 <p>Below is an example showing how to access an attribute 187 from the platform extension: 188 189 <p> 190 1) Direct access to the Oracle-specific MXBean interface 191 <blockquote> 192 <pre> 193 List<com.sun.management.GarbageCollectorMXBean> mxbeans = 194 ManagementFactory.getPlatformMXBeans(com.sun.management.GarbageCollectorMXBean.class); 195 196 for (com.sun.management.GarbageCollectorMXBean gc : mxbeans) { 197 // Get the standard attribute "CollectionCount" 198 String count = mxbean.getCollectionCount(); 199 200 // Get the platform-specific attribute "LastGcInfo" 201 GcInfo gcinfo = gc.getLastGcInfo(); 202 ... 203 } 204 </pre> 205 </blockquote> 206 207 <p> 208 2) Access the Oracle-specific MXBean interface via <tt>MBeanServer</tt> 209 through proxy 210 211 <blockquote><pre> 212 MBeanServerConnection mbs; 213 214 // Connect to a running JVM (or itself) and get MBeanServerConnection 215 // that has the JVM MXBeans registered in it 216 ... 217 218 List<com.sun.management.GarbageCollectorMXBean> mxbeans = 219 ManagementFactory.getPlatformMXBeans(mbs, com.sun.management.GarbageCollectorMXBean.class); 220 221 for (com.sun.management.GarbageCollectorMXBean gc : mxbeans) { 222 // Get the standard attribute "CollectionCount" 223 String count = mxbean.getCollectionCount(); 224 225 // Get the platform-specific attribute "LastGcInfo" 226 GcInfo gcinfo = gc.getLastGcInfo(); 227 ... 228 } 229 </pre></blockquote> 230 231 <p> Unless otherwise noted, passing a <tt>null</tt> argument to a constructor 232 or method in any class or interface in this package will cause a {@link 233 java.lang.NullPointerException NullPointerException} to be thrown. 234 235 <p> The java.lang.management API is thread-safe. 236 237 @see <a href="../../../javax/management/package-summary.html"> 238 JMX Specification.</a> 239 240 @author Mandy Chung 241 @since 1.5 242 243 </body> 244 </html>