code: public static JVMMemoryInfo getJVMMemoryInfo() {
          Runtime runtime = Runtime.getRuntime();
          double freeMemory = (double) runtime.freeMemory() / (1024 * 1024);
          double maxMemory = (double) runtime.maxMemory() / (1024 * 1024);
          double totalMemory = (double) runtime.totalMemory() / (1024 * 1024);
          return new JVMMemoryInfo(freeMemory, maxMemory, totalMemory);
      }
docs: 获取JVM虚拟机内存信息
  
  @return JVM虚拟机内存信息