查看运行时对象大小

// JDK 原生 API
System.setProperty("java.vm.name", "Java HotSpot(TM) ");
System.out.println(ObjectSizeCalculator.getObjectSize(onlineChangeReportDetails));

// org.apache.lucene.
System.out.println("value is " + RamUsageEstimator.sizeOf(onlineChangeReportDetails));
System.out.println(" value is " + RamUsageEstimator.humanSizeOf(onlineChangeReportDetails));