监控JVM内存使用情况，剩余空间小于2M时报警

一个简单的类，用来监控JVM内存使用情况，剩余空间小于2M时报警。

import java.lang.management.ManagementFactory;

import java.lang.management.OperatingSystemMXBean;

import java.lang.reflect.Method;

/**

 * Test

 */

public class Test {

    public static void main(String[] args) throws InterruptedException {

        Runtime runtime = Runtime.getRuntime();

        while (true) {

            long freeMemory = runtime.freeMemory();

            long totalMemory = runtime.totalMemory();

            long maxMemory = runtime.maxMemory();

            String msg = "max:" + (maxMemory / 1024 / 1024) + "M,total:" + (totalMemory / 1024 / 1024) + "M,used:"

                    + ((totalMemory / 1024 / 1024) - (freeMemory / 1024 / 1024)) + "M,free:"

                    + (freeMemory / 1024 / 1024) + "M";

            boolean ok = (maxMemory - (totalMemory - freeMemory) > 2048); // 剩余空间小于2M报警

            if (!ok) {

                System.out.println(msg);

                System.err.println("剩余空间小于2M报警");

            }

            Thread.currentThread().sleep(1 * 1000);

        }

    }

}