SpringBoot整合MyBatis-Plus的坑

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found):

踩坑springboot整合mybatis-plus启动后报
org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.bdqn.data.service.UserService.getBaseMapper
（下面还有一大堆错误，我只截取了这一段主要的）

找了很多别人的文章，都是说mapper文件的namespace的问题，还有的说的是jar包冲突问题，但是我用mybatis-plus压根就没写mapper映射文件，只是用它做一个简单的查询测试，jar包也没问题，最终费劲所思，自己摸索 试出来了问题原因。

先上一下报错代码
实体类代码

@Data
@TableName("users")
public class Users {
    private Integer id;
    private String userName;
    private String password;
}

dao接口

注意我在dao接口并没有写@Mapper注解，而是在启动类上加了@MapperScan注解

public interface UserDao extends BaseMapper<Users> {
//只需要继承继承BaseMapper，泛型类型写我们要操作的表(实体类名字)就可以实现crud操作了
}

service接口

public interface UserService extends IService<Users> {

}

service实现类

@Service
public class UserServiceImpl extends ServiceImpl<UserDao,Users> implements UserService {

}

controller类

    @Autowired
    UserService userService;

    @RequestMapping("/Info")
    public String test(){
        List<Users> list = userService.list();
        System.out.println(list.size());
        return "index";
    }

springboot启动类

在启动类加了@MapperScan注解

@SpringBootApplication
@MapperScan
public class TestdatasourceApplication {

    public static void main(String[] args) {
        SpringApplication.run(TestdatasourceApplication.class, args);
    }

}

此时此刻，启动项目，访问/Info(我的controller映射路径)
就会报如下错误

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.bdqn.data.service.UserService.getBaseMapper
	at org.apache.ibatis.binding.MapperMethod$SqlCommand.<init>(MapperMethod.java:235) ~[mybatis-3.5.6.jar:3.5.6]
	at com.baomidou.mybatisplus.core.override.MybatisMapperMethod.<init>(MybatisMapperMethod.java:51) ~[mybatis-plus-core-3.4.1.jar:3.4.1]
	at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.lambda$cachedInvoker$0(MybatisMapperProxy.java:111) ~[mybatis-plus-core-3.4.1.jar:3.4.1]
	at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660) ~[na:1.8.0_74]
	at com.baomidou.mybatisplus.core.toolkit.CollectionUtils.computeIfAbsent(CollectionUtils.java:117) ~[mybatis-plus-core-3.4.1.jar:3.4.1]
	at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.cachedInvoker(MybatisMapperProxy.java:98) ~[mybatis-plus-core-3.4.1.jar:3.4.1]
	at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.invoke(MybatisMapperProxy.java:89) ~[mybatis-plus-core-3.4.1.jar:3.4.1]
	at com.sun.proxy.$Proxy58.getBaseMapper(Unknown Source) ~[na:na]
	at com.baomidou.mybatisplus.extension.service.IService.list(IService.java:279) ~[mybatis-plus-extension-3.4.1.jar:3.4.1]
	at java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:627) ~[na:1.8.0_74]
	at com.baomidou.mybatisplus.core.override.MybatisMapperProxy$DefaultMethodInvoker.invoke(MybatisMapperProxy.java:162) ~[mybatis-plus-core-3.4.1.jar:3.4.1]
	at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.invoke(MybatisMapperProxy.java:89) ~[mybatis-plus-core-3.4.1.jar:3.4.1]
	at com.sun.proxy.$Proxy58.list(Unknown Source) ~[na:na]
	at com.baomidou.mybatisplus.extension.service.IService.list(IService.java:288) ~[mybatis-plus-extension-3.4.1.jar:3.4.1]
	at java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:627) ~[na:1.8.0_74]
	at com.baomidou.mybatisplus.core.override.MybatisMapperProxy$DefaultMethodInvoker.invoke(MybatisMapperProxy.java:162) ~[mybatis-plus-core-3.4.1.jar:3.4.1]
	at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.invoke(MybatisMapperProxy.java:89) ~[mybatis-plus-core-3.4.1.jar:3.4.1]
	at com.sun.proxy.$Proxy58.list(Unknown Source) ~[na:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_74]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_74]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_74]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_74]
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208) ~[spring-aop-5.3.3.jar:5.3.3]
	at com.sun.proxy.$Proxy60.list(Unknown Source) ~[na:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_74]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_74]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_74]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_74]
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208) ~[spring-aop-5.3.3.jar:5.3.3]
	at com.sun.proxy.$Proxy60.list(Unknown Source) ~[na:na]
	at com.bdqn.data.controller.MyController.test(MyController.java:40) ~[classes/:na]
	at com.bdqn.data.controller.MyController$$FastClassBySpringCGLIB$$ae3bf9d8.invoke(<generated>) ~[classes/:na]
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:779) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) ~[spring-aop-5.3.3.jar:5.3.3]
	at com.alibaba.druid.support.spring.stat.DruidStatInterceptor.invoke(DruidStatInterceptor.java:73) ~[druid-1.1.14.jar:1.1.14]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:692) ~[spring-aop-5.3.3.jar:5.3.3]
	at com.bdqn.data.controller.MyController$$EnhancerBySpringCGLIB$$1103b392.test(<generated>) ~[classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_74]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_74]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_74]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_74]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.3.jar:5.3.3]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894) ~[spring-webmvc-5.3.3.jar:5.3.3]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.3.jar:5.3.3]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.3.jar:5.3.3]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1060) ~[spring-webmvc-5.3.3.jar:5.3.3]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:962) ~[spring-webmvc-5.3.3.jar:5.3.3]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.3.jar:5.3.3]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.3.jar:5.3.3]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) ~[tomcat-embed-core-9.0.41.jar:4.0.FR]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.3.jar:5.3.3]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.41.jar:4.0.FR]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at com.alibaba.druid.support.http.WebStatFilter.doFilter(WebStatFilter.java:124) ~[druid-1.1.14.jar:1.1.14]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.3.jar:5.3.3]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.3.jar:5.3.3]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.3.jar:5.3.3]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:888) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1597) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_74]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_74]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.41.jar:9.0.41]
	at java.lang.Thread.run(Thread.java:745) [na:1.8.0_74]

当时我实在看不出哪写错了，网上也没有找到解决方案

于是，千试百试，终于解决了

就是扫描dao接口的问题

解决方案1
在dao接口上标注@Mapper注解
把启动类上的@MapperScan注解去掉

@Mapper
public interface UserDao extends BaseMapper<Users> {
//只需要继承继承BaseMapper，泛型类型写我们要操作的表(实体类名字)就可以实现crud操作了
}

启动，访问，正确无误！但是这种方式如果dao接口多了，就得每一个dao接口都得加@Mapper注解，不方便

解决方案2
dao接口不变，不加@Mapper注解
在启动类上对@MapperScan注解进行改动
指定@MapperScan要扫描的包

@SpringBootApplication
@MapperScan("cn.atckt.test.dao")
public class TestdatasourceApplication {
    public static void main(String[] args) {
        SpringApplication.run(TestdatasourceApplication.class, args);
    }
}

启动，访问，也是正常的！

得出结论：@MapperScan不指定包的时候，扫描当前包以及其所有子包，子包有很多，不知道先扫描到容器是哪一个，导致最后调用出了问题，所以尽量直接指定要扫描的包 或单个使用@Mapper注解，具体原因，没有跟进调查，感兴趣的朋友可以详细调查一下@MapperScan以及@Mapper