Spring集成JPA配置懒加载报错解决方案
人气:1一:报错no session
因为entitymanager对象在事物提交后就关闭了 报错的 no session相当于sql的session
解决办法:解决办法 在web.xmL配置一个过滤器 使其在这个session中的manager在结束后再关闭open
<!--配置openmanager--> <filter> <filter-name>openEntity</filter-name> <filter-class>org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter</filter-class> </filter> <filter-mapping> <filter-name>openEntity</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
在完成上面的配置后会报第二个错误
二 报错no serializer报错
解决办法1:在需要配置懒加载的字段上加 @JsonIgnoreProperties(value = {"hibernateLazyInitializer","handler","fieldHandler"})这种方式只管当前字段属性的懒加载
@ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name="department_id") @JsonIgnoreProperties(value = {"hibernateLazyInitializer","handler","fieldHandler"}) private Department department;
解决办法2:重写:ObjectMapper,然后在applicationContext-mvc.xml 配置这个映射(这个方法一劳永逸,之后在Spring集成JPA进行懒加载的时候,都会避免No serializer的错误)
第一步:
public class CustomMapper extends ObjectMapper { public CustomMapper() { this.setSerializationInclusion(JsonInclude.Include.NON_NULL); // 设置 SerializationFeature.FAIL_ON_EMPTY_BEANS 为 false this.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false); } }
第二步:配置spring-mvc.xml
<!--注解支持--> <mvc:annotation-driven> <mvc:message-converters> <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"> <property name="supportedMediaTypes"> <list> <value>application/json; charset=UTF-8</value> <value>application/x-www-form-urlencoded; charset=UTF-8</value> </list> </property> <!-- No serializer:配置 objectMapper 为我们自定义扩展后的 CustomMapper,解决了返回对象有关系对象的报错问题 --> <property name="objectMapper"> <bean class="com.logo.aisell.util.CustomMapper"></bean> </property> </bean> </mvc:message-converters> </mvc:annotation-driven>
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