解决tk mapper 通用mapper的bug问题

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的属性值 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）项目升级通用Mapper引发的一连串问题以及问题解决

项目环境

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>

公司统一封装了三个核心包（kemean-aid、kemean-third、kemean-web），平时技术开发都是把三核心包下载源码到本地启动运行，这个星期把三个核心包打包成jar，让项目依赖jar启动，但启动的时候报了一个maven错误（问题一）。

问题一

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报了一个重复引用通用Mapper Jar错误，但反复查看maven引用，并没有发现有重复引用通用Mapper jar包，而且项目引用源码启动是正常运行的，这个问题着实报得有点诡异！因为经验问题，重复就maven报的这个问题寻找重复引用的jar，然而处理了很久也并没有解决。后来查看通用mapper的版本maven仓库（https://mvnrepository.com/artifact/tk.mybatis/mapper-spring-boot-starter） ，发现公司现在使用的版本已经更新好多个版本了，第一直觉认为是公司用的1.1.5这个版本有问题，于是乎升级了通用mapper版本到2版本（当前最新2.0.4），就这样掉大坑了，开始一系列的问题解决的路程。

 <dependency>
     <groupId>tk.mybatis</groupId>
     <artifactId>mapper-spring-boot-starter</artifactId>
     <version>2.0.4</version>
 </dependency>

以下的问题都是在2版本的通用mapper中遇到的

问题二

tk.mybatis.mapper.MapperException: 无法获取实体类com.kemean.bean.KemeanAdminUser对应的表名!

github也有此问题的讨论：https://github.com/abel533/MyBatis-Spring-Boot/issues/18

问题解决

修改启动类@MapperScan注解

2版本的通用Mapper提供了@MapperScan注解，之前我们使用的是org.mybatis.spring.annotation.MapperScan，现需把@MapperScan改为tk.mybatis.spring.annotation.MapperScan

添加spring-devtools.properties文件

在项目src/main/resources目录新建一个文件夹META-INF（项目右键-new-Source Folder），添加热部署配置文件spring-devtools.properties，在文件里面添加restart.include.companycommonlibs=tk/mybatis.*

问题三

tk.mybatis.mapper.MapperException: tk.mybatis.mapper.provider.EmptyProvider中缺少selectOne方法!

github也有此问题的讨论：

https://github.com/abel533/MyBatis-Spring-Boot/issues/92

https://github.com/abel533/MyBatis-Spring-Boot/issues/53

问题解决：把项目热部署去掉

<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-devtools</artifactId>
 <scope>runtime</scope>
</dependency>

在处理完问题二、三，通用Mapper就升级成功了，项目也能够正常启动访问，但是，咱们在处理问题三的时候，把spring boot的热部署给去掉了，这就意味着咱们日后每改动一点，都需要重新启动部署服务，这是士可忍，叔不可忍；叔可忍，婶也不能忍的操作啊。

尝试过好多方式，都不能“升级通用mapper2版本”与“保留Spring boot热部署”两个兼得，后来看到这哥们的一句话，给了我一个提醒，于是乎在刚才添加的spring-devtools.properties文件再补充一行restart.include.companycommonlibs=kemean.*

spring-devtools.properties内容（kemean.*是公司jar的前缀）

restart.include.companycommonlibs=tk/mybatis.*
restart.include.companycommonlibs=kemean.* 

https://github.com/abel533/MyBatis-Spring-Boot/issues/53

再启动服务，服务正常使用，热部署也能够保留

问题一的最终解决

结合问题三的解决思路，那么咱们在不升级通用mapper的前提下，让项目依赖打包出来的jar运行，则仅需在

项目src/main/resources目录新建一个文件夹META-INF（项目右键-new-Source Folder），添加热部署配置文件spring-devtools.properties，在文件里面添加

restart.include.companycommonlibs=kemean.* 

问题一就在不升级通用mapper下完美解决了~

以上为个人经验，希望能给大家一个参考，也希望大家多多支持我们。