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>
