对象属性选择性拷贝 JAVA生成密码随机数

org.springframework.beans.BeanUtils.copyProperties(source, target,new String[]{'userId',  'modifyBy', 'modifyAt'}) 
StringBuffer sb = new StringBuffer(); String str = '0123456789'; Random r = new Random(); for(int i=0;i       int num = r.nextInt(str.length());       sb.append(str.charAt(num));       str = str.replace((str.charAt(num)+''), ''); } return sb.toString();