解決tk mapper 通用mapper的bug問題
如下所示：
<bean class="tk.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.isea533.mybatis.mapper"/>
<property name="properties">
<value>
mappers=tk.mybatis.mapper.common.Mapper
</value>
</property>
</bean>
basePackage的屬性值 不能包含通用mapper所在的包
Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2018-03-14 12:39:21.741 ERROR [main] [hio-sys] o.s.boot.SpringApplication - Application startup failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'tk.mybatis.mapper.autoconfigure.MapperAutoConfiguration': Invocation of init method failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'baseMapper' defined in file []: Invocation of init method failed; nested exception is tk.mybatis.mapper.MapperException: tk.mybatis.mapper.MapperException: java.lang.ClassCastException: sun.reflect.generics.reflectiveObjects.TypeVariableImpl cannot be cast to java.lang.Class
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:137)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:409)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1620)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
at org.springframework.context.support.AbstractApplicationContext.__refresh(AbstractApplicationContext.java:543)
at org.springframework.context.support.AbstractApplicationContext.jrLockAndRefresh(AbstractApplicationContext.java)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:303)
at com.jzy.hio.HioSysApplication.main(HioSysApplication.java:35)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'baseMapper' defined in file [C:\Users\coffee\OneDrive\workspace\v2r1-hio-base\target\classes\com\jzy\hio\base\mapper\BaseMapper.class]: Invocation of init method failed; nested exception is tk.mybatis.mapper.MapperException: tk.mybatis.mapper.MapperException: java.lang.ClassCastException: sun.reflect.generics.reflectiveObjects.TypeVariableImpl cannot be cast to java.lang.Class
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType_jrOrig(DefaultListableBeanFactory.java:519)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType_jrOrig(DefaultListableBeanFactory.java:508)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java)
at org.springframework.context.support.AbstractApplicationContext.getBeansOfType(AbstractApplicationContext.java:1188)
at tk.mybatis.mapper.autoconfigure.MapperAutoConfiguration.addPageInterceptor(MapperAutoConfiguration.java:71)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.__invoke(DelegatingMethodAccessorImpl.java:43)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:366)
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:311)
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:134)
... 18 common frames omitted
Caused by: tk.mybatis.mapper.MapperException: tk.mybatis.mapper.MapperException: java.lang.ClassCastException: sun.reflect.generics.reflectiveObjects.TypeVariableImpl cannot be cast to java.lang.Class
at tk.mybatis.mapper.mapperhelper.MapperHelper.setSqlSource(MapperHelper.java:248)
at tk.mybatis.mapper.mapperhelper.MapperHelper.processConfiguration(MapperHelper.java:311)
at tk.mybatis.spring.mapper.MapperFactoryBean.checkDaoConfig(MapperFactoryBean.java:54)
at org.springframework.dao.support.DaoSupport.afterPropertiesSet(DaoSupport.java:44)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624)
... 39 common frames omitted
Caused by: tk.mybatis.mapper.MapperException: java.lang.ClassCastException: sun.reflect.generics.reflectiveObjects.TypeVariableImpl cannot be cast to java.lang.Class
at tk.mybatis.mapper.mapperhelper.MapperTemplate.setSqlSource(MapperTemplate.java:258)
at tk.mybatis.mapper.mapperhelper.MapperHelper.setSqlSource(MapperHelper.java:245)
... 44 common frames omitted
Caused by: java.lang.ClassCastException: sun.reflect.generics.reflectiveObjects.TypeVariableImpl cannot be cast to java.lang.Class
at tk.mybatis.mapper.mapperhelper.MapperTemplate.getEntityClass(MapperTemplate.java:290)
at tk.mybatis.mapper.provider.base.BaseSelectProvider.selectOne(BaseSelectProvider.java:50)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.__invoke(DelegatingMethodAccessorImpl.java:43)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at java.lang.reflect.Method.invoke(Method.java:498)
at tk.mybatis.mapper.mapperhelper.MapperTemplate.setSqlSource(MapperTemplate.java:246)
... 45 common frames omitted
（通用mapper）項目升級通用Mapper引發的一連串問題以及問題解決
項目環境
通用Mapper版本
<dependency> <groupId>tk.mybatis</groupId> <artifactId>mapper-spring-boot-starter</artifactId> <version>1.1.5</version> </dependency>
Spring boot版本
<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> <relativePath /> </parent>
公司統一封裝瞭三個核心包（kemean-aid、kemean-third、kemean-web），平時技術開發都是把三核心包下載源碼到本地啟動運行，這個星期把三個核心包打包成jar，讓項目依賴jar啟動，但啟動的時候報瞭一個maven錯誤（問題一）。
問題一
Caused by: java.lang.LinkageError: loader constraint violation: loader (instance of org/springframework/boot/devtools/restart/classloader/RestartClassLoader) previously initiated loading for a different type with name “tk/mybatis/mapper/common/Mapper”
maven報瞭一個重復引用通用Mapper Jar錯誤，但反復查看maven引用，並沒有發現有重復引用通用Mapper jar包，而且項目引用源碼啟動是正常運行的，這個問題著實報得有點詭異！因為經驗問題，重復就maven報的這個問題尋找重復引用的jar，然而處理瞭很久也並沒有解決。後來查看通用mapper的版本maven倉庫（https://mvnrepository.com/artifact/tk.mybatis/mapper-spring-boot-starter） ，發現公司現在使用的版本已經更新好多個版本瞭，第一直覺認為是公司用的1.1.5這個版本有問題，於是乎升級瞭通用mapper版本到2版本（當前最新2.0.4），就這樣掉大坑瞭，開始一系列的問題解決的路程。
<dependency>
<groupId>tk.mybatis</groupId>
<artifactId>mapper-spring-boot-starter</artifactId>
<version>2.0.4</version>
</dependency>
以下的問題都是在2版本的通用mapper中遇到的
問題二
tk.mybatis.mapper.MapperException: 無法獲取實體類com.kemean.bean.KemeanAdminUser對應的表名!
github也有此問題的討論：https://github.com/abel533/MyBatis-Spring-Boot/issues/18
問題解決
修改啟動類@MapperScan註解
2版本的通用Mapper提供瞭@MapperScan註解，之前我們使用的是org.mybatis.spring.annotation.MapperScan，現需把@MapperScan改為tk.mybatis.spring.annotation.MapperScan
添加spring-devtools.properties文件
在項目src/main/resources目錄新建一個文件夾META-INF（項目右鍵-new-Source Folder），添加熱部署配置文件spring-devtools.properties，在文件裡面添加restart.include.companycommonlibs=tk/mybatis.*
問題三
tk.mybatis.mapper.MapperException: tk.mybatis.mapper.provider.EmptyProvider中缺少selectOne方法!
github也有此問題的討論：
https://github.com/abel533/MyBatis-Spring-Boot/issues/92
https://github.com/abel533/MyBatis-Spring-Boot/issues/53
問題解決：把項目熱部署去掉
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> </dependency>
在處理完問題二、三，通用Mapper就升級成功瞭，項目也能夠正常啟動訪問，但是，咱們在處理問題三的時候，把spring boot的熱部署給去掉瞭，這就意味著咱們日後每改動一點，都需要重新啟動部署服務，這是士可忍，叔不可忍；叔可忍，嬸也不能忍的操作啊。
嘗試過好多方式，都不能“升級通用mapper2版本”與“保留Spring boot熱部署”兩個兼得，後來看到這哥們的一句話，給瞭我一個提醒，於是乎在剛才添加的spring-devtools.properties文件再補充一行restart.include.companycommonlibs=kemean.*
spring-devtools.properties內容（kemean.*是公司jar的前綴）
restart.include.companycommonlibs=tk/mybatis.* restart.include.companycommonlibs=kemean.*
https://github.com/abel533/MyBatis-Spring-Boot/issues/53
再啟動服務，服務正常使用，熱部署也能夠保留
問題一的最終解決
結合問題三的解決思路，那麼咱們在不升級通用mapper的前提下，讓項目依賴打包出來的jar運行，則僅需在
項目src/main/resources目錄新建一個文件夾META-INF（項目右鍵-new-Source Folder），添加熱部署配置文件spring-devtools.properties，在文件裡面添加
restart.include.companycommonlibs=kemean.*
問題一就在不升級通用mapper下完美解決瞭~
以上為個人經驗，希望能給大傢一個參考，也希望大傢多多支持WalkonNet。
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