get directmemory usage

directmemory.jsp

<%@ page import="java.lang.management.BufferPoolMXBean" %>
<%@ page import="java.util.List" %>
<%@ page import="java.lang.management.ManagementFactory" %><%--
  Created by IntelliJ IDEA.
  User: qishengli
  Date: 18-6-6
  Time: 上午11:40
  To change this template use File | Settings | File Templates.
--%>
<%
    List<BufferPoolMXBean> pools = ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class);
    for (BufferPoolMXBean pool : pools) {
        out.write("<BR>name: " + pool.getName());
        out.write("<BR>count: " + pool.getCount());
        out.write("<BR>memory used: " + toMB(pool.getMemoryUsed()));
        out.write("<BR>total capacity: " + toMB(pool.getTotalCapacity()));
        out.write("<BR><BR><BR><BR>");
    }
%>

<%!
    private static String toMB(long init) {
        return (Long.valueOf(init).doubleValue() / (1024 * 1024)) + " MB";
    }
%>

see: https://stackoverflow.com/questions/20058489/is-there-a-way-to-measure-direct-memory-usage-in-java