java - 如何使用 JMX API 获取 tomcat 7 的内存使用情况？

Question

是否可以使用 JMX API 获取 tomcat 服务器的内存使用统计信息。哪个 Mbean 可以向我提供此信息？我在下面的代码中停留在 ObjectName 的形成上

JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:2020/jmxrmi");
JMXConnector jmxc = JMXConnectorFactory.connect(url);
MBeanServerConnection server = jmxc.getMBeanServerConnection();

  Object o = jmxc.getMBeanServerConnection().getAttribute(
          new ObjectName("-----"); 

想知道 jconsole 是如何绘制内存图的，有源代码的指针吗？

Answer 1

MBeanServer connection = ManagementFactory.getPlatformMBeanServer();
Set<ObjectInstance> set = connection.queryMBeans(new ObjectName("java.lang:type=Memory"), null);
ObjectInstance oi = set.iterator().next();
// replace "HeapMemoryUsage" with "NonHeapMemoryUsage" to get non-heap mem
Object attrValue = connection.getAttribute(oi.getObjectName(), "HeapMemoryUsage");
if( !( attrValue instanceof CompositeData ) ) {
    System.out.println( "attribute value is instanceof [" + attrValue.getClass().getName() +
            ", exitting -- must be CompositeData." );
    return;
}
// replace "used" with "max" to get max
System.out.println(((CompositeData)attrValue).get("used").toString());