在使用Mybatis的过程中,使用了resultMap延迟加载。
延迟加载:association联表查询的过程中,查询另外两个表的对象。而延迟加载是指只有在使用这两个对象的时候才会进行查询。
问题的产生,在我这里,我是直接通过路由url直接查询 StudentDto_2 对象。延迟加载的对象为 TClass 和 Assistant.
public class StudentDto_2 {
private Integer stuId;
private String stuNum; //学生编号,unique
private String studentName;
private Long birthDate;
private TClass tClass;
private Assistant assistant;
}
在序列化的过程中,会抛出以下异常。
2018-08-27 11:14:29.339 ERROR 34755 --- [nio-8089-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class org.apache.ibatis.executor.loader.javassist.JavassistProxyFactory$EnhancedResultObjectProxyImpl]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class org.apache.ibatis.executor.loader.javassist.JavassistProxyFactory$EnhancedResultObjectProxyImpl and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: com.zimo.mybaties.util.Result["data"]->com.zimo.mybaties.dto.StudentDto_2_$$_jvstfe4_0["handler"])] with root cause
问题:Springmvc+mybatis,mybatis配置延迟加载时,json序列化异常
我目前的解决办法是关闭延迟加载,关闭后一切正常。
寻找另外一种方法
参考链接:https://blog.csdn.net/justinytsoft/article/details/53575236
在SpringBoot中,默认使用Jackson来实现java对象到json格式的序列化与反序列化。Jackson的转化是通过ObjectMapper来实现的。SpringBoot内置了一个ObjectMapper。我们通过下面的配置来
实现序列化Mybatis的延迟加载。
package com.zimo.mybaties.config;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import org.springframework.context.annotation.Configuration;
@Configuration
public class CustomerMapper extends ObjectMapper {
public CustomerMapper() {
this.setSerializationInclusion(JsonInclude.Include.NON_NULL); //返回为null的值则去除,
this.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS,false); //解决延迟加载的对象
}
}
返回参数中了多了一个代理对象handle
{
"code": 200,
"message": "获取学生信息",
-"data": {
"stuId": 22,
"stuNum": "12310",
"studentName": "天涯10",
"birthDate": 777524356000,
-"tClass": {
"classId": 3,
"classNum": "1921083145",
"className": "数学"
},
-"assistant": {
"assistantId": 1,
"assistantNum": "1315151521",
"name": "还在于是"
},
"handler": { }
}
}
转自:https://www.cnblogs.com/wbq1113/p/9541114.html |