查看对象占用的内存大小

 

        Runtime.getRuntime().gc();
        long start = Runtime.getRuntime().freeMemory();
        Object object=(Object)request.getSession().getAttribute("object");
       
        Runtime.getRuntime().gc();
        long end = Runtime.getRuntime().freeMemory();
        long difference = ( start -  end );
        System.out.println( difference + " bytes be used!" );