java 查看类大小

   // 结果数据
            long gcing = Runtime.getRuntime().freeMemory();
            orderList = pageOrder.getRecords();
            long gced = Runtime.getRuntime().freeMemory();
            // 64位打印24，32位打印16 （注:是因为JVM底层内存都是以8 byte对齐的,即8的倍数）
            System.out.println("Memory used:"+(gcing -gced ));
            long size= ObjectSizeCalculator.getObjectSize(orderList);
            System.out.println("Memory used:"+size);