There is no getter for property named '*' in 'class java.lang.String'，此错误之所以出现，是因为mybatis在对parameterType="String"的sql语句做了限制，假如你使用<when test="username != null">这样的条件判断时，就会出现该错误

报信息如下

.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'provName' in 'class java.lang.String'   at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:77)   at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446)   at com.sun.proxy.$Proxy97.selectList(Unknown Source)   at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:230)   at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:137)   at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:75)   at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)   at com.sun.proxy.$Proxy125.getSchoolInfoByProvName(Unknown Source)   at cn.ls.tcis.service.impl.barnswallow.BarnSwallowInfoServiceImpl.getDistributeAge(BarnSwallowInfoServiceImpl.java:243)   at cn.ls.tcis.controller.pc.StatisticController.getDistributeAge(StatisticController.java:94)   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.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189)   at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)   at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)   at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)   at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)   at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)   at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)   at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)   at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)   at org.springframework.web.servl

mapper接口

parameterType="String"，这一点是必须得，参数类型必须是string。
该sql对应的mapper class中对应的方法为

List<SchoolInfoDO> getSchoolInfoByProvName(String provName);也就是说，传递的参数名为provName，正常情况下，这样的配置合情合理。
<when test="provName != null">，你有一个对应的test判断语句，也可能是if。
那么这个时候，项目运行该查询语句时，就会抛出There is no getter for property named 'username' in 'class java.lang.String'错误！ 

解决办法很简单，你只需要把 <when test="provName != null">修改为 <when test="_parameter!= null">就好了

修改完以后

解决方法

 <if test="_parameter !=null">
      
  </if>