MyBatis 封装返回类型中包含内部类

oldFarmer
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1.1类结构

package com.atguigu.gulimall.product.vo;

import com.atguigu.gulimall.product.entity.SkuImagesEntity;
import com.atguigu.gulimall.product.entity.SkuInfoEntity;
import com.atguigu.gulimall.product.entity.SpuInfoDescEntity;
import lombok.Data;

import java.util.List;

@Data
public class SkuItemVo {
    List<ItemSaleAttrVo> saleAttr;
    List<SpuItemBaseAttrVo> groupAttrs;
    @Data
    public static class ItemSaleAttrVo{
        private Long attrId;
        private String attrName;
        private List<String> attrValues;
    }
    @Data
    public static class SpuItemBaseAttrVo{
        private String groupName;
        private List<SpuBaseAttrVo> attrs;

    }
    @Data
    public static class SpuBaseAttrVo{
        private String attrName;
        private String attrValue;
    }
}

1.2查询sql语句

SELECT
	pav.spu_id,
	arg.attr_group_id,
	arg.attr_group_name,
	aar.attr_id,
	pav.attr_name,
	pav.attr_value
FROM
	pms_attr_group arg
LEFT JOIN pms_attr_attrgroup_relation aar ON arg.attr_group_id = aar.attr_group_id
LEFT JOIN pms_attr atr ON atr.attr_id = aar.attr_id
LEFT JOIN pms_product_attr_value pav ON pav.attr_id = atr.attr_id
WHERE
	arg.catelog_id = 225
AND pav.spu_id = 4;

如果要将数据库查询出的attr_group_name，attr_name，attr_value封装到SpuItemBaseAttrVo 我们写的xml示例如下

<resultMap id="SpuItemBaseAttrVo1" type="com.atguigu.gulimall.product.vo.SkuItemVo.SpuItemBaseAttrVo">
    <result column="attr_group_name" property="groupName" javaType="java.lang.String"></result>
    <collection property="attrs" ofType="com.atguigu.gulimall.product.vo.SkuItemVo.SpuBaseAttrVo">
        <result column="attr_name" property="attrName" javaType="java.lang.String"></result>
        <result column="attr_value" property="attrValue" javaType="java.lang.String"></result>
    </collection>
</resultMap>
<select id="getProductGroupAttrsBySpuId"
        resultMap="SpuItemBaseAttrVo1">
    SELECT
        pav.spu_id,
        arg.attr_group_id,
        arg.attr_group_name,
        aar.attr_id,
        pav.attr_name,
        pav.attr_value
    FROM
        pms_attr_group arg
            LEFT JOIN pms_attr_attrgroup_relation aar ON arg.attr_group_id = aar.attr_group_id
            LEFT JOIN pms_attr atr ON atr.attr_id = aar.attr_id
            LEFT JOIN pms_product_attr_value pav ON pav.attr_id = atr.attr_id
    WHERE
        arg.catelog_id =#{catalogId}
      AND pav.spu_id = #{spuId};
</select>

1.3测试

测试代码

@SpringBootTest
@RunWith(SpringRunner.class)
public class TestAttrGroupDao {
    @Autowired
    private AttrGroupService attrGroupService;
    @Test
    public void testgetProductGroupAttrsBySpuId(){
        List<SkuItemVo.SpuItemBaseAttrVo> productGroupAttrsBySpuId = attrGroupService.getProductGroupAttrsBySpuId(4L, 225L);
        System.out.println(productGroupAttrsBySpuId);
    }
}

主要报错信息

java.lang.IllegalStateException: Failed to load ApplicationContext

at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:125)
at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:108)
at org.springframework.test.context.web.ServletTestExecutionListener.setUpRequestContextIfNecessary(ServletTestExecutionListener.java:190)
at org.springframework.test.context.web.ServletTestExecutionListener.prepareTestInstance(ServletTestExecutionListener.java:132)
at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:246)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:227)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:246)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:221)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'attrAttrgroupRelationController': Unsatisfied dependency expressed through field 'attrAttrgroupRelationService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'attrAttrgroupRelationService': Unsatisfied dependency expressed through field 'baseMapper'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'attrAttrgroupRelationDao' defined in file [F:\gulimall\gulimall-product\target\classes\com\atguigu\gulimall\product\dao\AttrAttrgroupRelationDao.class]: Unsatisfied dependency expressed through bean property 'sqlSessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [com/baomidou/mybatisplus/autoconfigure/MybatisPlusAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.ibatis.session.SqlSessionFactory]: Factory method 'sqlSessionFactory' threw exception; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [F:\gulimall\gulimall-product\target\classes\mapper\product\AttrGroupDao.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'file [F:\gulimall\gulimall-product\target\classes\mapper\product\AttrGroupDao.xml]'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.atguigu.gulimall.product.vo.SkuItemVo.SpuItemBaseAttrVo'.  Cause: java.lang.ClassNotFoundException: Cannot find class: com.atguigu.gulimall.product.vo.SkuItemVo.SpuItemBaseAttrVo
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:596)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1411)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:845)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:312)
at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:120)
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:99)
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:117)
... 24 more
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'attrAttrgroupRelationService': Unsatisfied dependency expressed through field 'baseMapper'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'attrAttrgroupRelationDao' defined in file [F:\gulimall\gulimall-product\target\classes\com\atguigu\gulimall\product\dao\AttrAttrgroupRelationDao.class]: Unsatisfied dependency expressed through bean property 'sqlSessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [com/baomidou/mybatisplus/autoconfigure/MybatisPlusAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.ibatis.session.SqlSessionFactory]: Factory method 'sqlSessionFactory' threw exception; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [F:\gulimall\gulimall-product\target\classes\mapper\product\AttrGroupDao.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'file [F:\gulimall\gulimall-product\target\classes\mapper\product\AttrGroupDao.xml]'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.atguigu.gulimall.product.vo.SkuItemVo.SpuItemBaseAttrVo'.  Cause: java.lang.ClassNotFoundException: Cannot find class: com.atguigu.gulimall.product.vo.SkuItemVo.SpuItemBaseAttrVo
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:596)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1411)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1251)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1171)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:593)
... 42 more
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'attrAttrgroupRelationDao' defined in file [F:\gulimall\gulimall-product\target\classes\com\atguigu\gulimall\product\dao\AttrAttrgroupRelationDao.class]: Unsatisfied dependency expressed through bean property 'sqlSessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [com/baomidou/mybatisplus/autoconfigure/MybatisPlusAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.ibatis.session.SqlSessionFactory]: Factory method 'sqlSessionFactory' threw exception; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [F:\gulimall\gulimall-product\target\classes\mapper\product\AttrGroupDao.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'file [F:\gulimall\gulimall-product\target\classes\mapper\product\AttrGroupDao.xml]'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.atguigu.gulimall.product.vo.SkuItemVo.SpuItemBaseAttrVo'.  Cause: java.lang.ClassNotFoundException: Cannot find class: com.atguigu.gulimall.product.vo.SkuItemVo.SpuItemBaseAttrVo
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireByType(AbstractAutowireCapableBeanFactory.java:1515)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1395)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1251)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1171)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:593)
... 55 more

1.4解决办法

修改resultmap，将.改成$

<!-- 封装自定义结果集
备注 mybatis封装内部类两个必要条件：
     1》.内部类必须是静态，
     2》.vo.SkuItemVo$SpuBaseAttrVo，这里要用$代替原先的.-->
<resultMap id="SpuItemBaseAttrVo1" type="com.atguigu.gulimall.product.vo.SkuItemVo$SpuItemBaseAttrVo">
    <result column="attr_group_name" property="groupName" javaType="java.lang.String"></result>
    <collection property="attrs" ofType="com.atguigu.gulimall.product.vo.SkuItemVo$SpuBaseAttrVo">
        <result column="attr_name" property="attrName" javaType="java.lang.String"></result>
        <result column="attr_value" property="attrValue" javaType="java.lang.String"></result>
    </collection>
</resultMap>

重新测试，发现已经可以拿到返回结果了 image.png

1.5如果bean的内部类不是static

package com.atguigu.gulimall.product.vo;

import com.atguigu.gulimall.product.entity.SkuImagesEntity;
import com.atguigu.gulimall.product.entity.SkuInfoEntity;
import com.atguigu.gulimall.product.entity.SpuInfoDescEntity;
import lombok.Data;

import java.util.List;

@Data
public class SkuItemVo {
    List<ItemSaleAttrVo> saleAttr;
    List<SpuItemBaseAttrVo> groupAttrs;
    @Data
    public  class ItemSaleAttrVo{
        private Long attrId;
        private String attrName;
        private List<String> attrValues;
    }
    @Data
    public  class SpuItemBaseAttrVo{
        private String groupName;
        private List<SpuBaseAttrVo> attrs;

    }
    @Data
    public  class SpuBaseAttrVo{
        private String attrName;
        private String attrValue;
    }
}

然后再进行测试 主要报错信息如下

Caused by: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.atguigu.gulimall.product.vo.SkuItemVo$SpuItemBaseAttrVo with invalid types (SkuItemVo) or values (4). Cause: java.lang.IllegalArgumentException: argument type mismatch
	at org.apache.ibatis.reflection.factory.DefaultObjectFactory.instantiateClass(DefaultObjectFactory.java:88)
	at org.apache.ibatis.reflection.factory.DefaultObjectFactory.create(DefaultObjectFactory.java:53)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createUsingConstructor(DefaultResultSetHandler.java:676)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createByConstructorSignature(DefaultResultSetHandler.java:654)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:618)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:591)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(DefaultResultSetHandler.java:898)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForNestedResultMap(DefaultResultSetHandler.java:870)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:326)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSet(DefaultResultSetHandler.java:301)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSets(DefaultResultSetHandler.java:194)
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:65)
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:79)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:63)
	at com.sun.proxy.$Proxy157.query(Unknown Source)
	at com.baomidou.mybatisplus.core.executor.MybatisSimpleExecutor.doQuery(MybatisSimpleExecutor.java:67)
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:324)
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
	at com.baomidou.mybatisplus.core.executor.MybatisCachingExecutor.query(MybatisCachingExecutor.java:163)
	at com.baomidou.mybatisplus.core.executor.MybatisCachingExecutor.query(MybatisCachingExecutor.java:90)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:147)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:426)
	... 42 more

总结MyBatis封装返回类型中包含内部类需要注意这两点

  • 内部类必须是静态内部类。
  • xml中内部类连接使用$
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