情况：

控制台打出java.lang.IllegalStateException: getOutputStream() has already been called for this response，页面没反应。 使用架构：easyui+sping3 MVC + jpa 页面用easyui-datagrid 查询并展示一个列表。 数据表结构： order( orderid ) order_detail( orderDetailId, orderId ) 实体配置： @Entity @Table(name="ORDER") @JsonIgnoreProperties( value={"hibernateLazyInitializer","handler"}) public class OrderBO extends BaseEntity {          @Id       private String orderId;          @OneToOne(targetEntity=OrderDetailBO.class,optional = true,fetch=FetchType.LAZY)     @JoinColumn(name="orderId",insertable=true,updatable=true)     private OrderDetailBO orderDetailBO;         } @Entity @Table(name="ORDER_DETAIL") @JsonIgnoreProperties( value={"hibernateLazyInitializer","handler"}) public class OrderDetailBO  extends BaseEntity{          @Id           private String orderDetailId;     private String orderId;              @OneToOne(targetEntity=OrderBO.class,optional = true,fetch=FetchType.LAZY)     @JoinColumn(name="orderId",insertable=true,updatable=true)     private OrderBO orderBO;         } service层查询hql: select new map(orderDetailBo as orderDetailBo,orderDetailBo.orderDetailId as uid) from OrderDetailBO orderDetailBo,OrdersBO ordersBo where orderDetailBo.orderId = ordersBo.orderId 查询结果Map 返回页面报错java.lang.IllegalStateException: getOutputStream() has already been called for this response 经过反复调试，需要设置orderDetailBo.getOrderBO().setOrderDetailBO(null)可以解决。 为什么会是这样，请高手求解！！！