解决Error querying database. Cause: java.lang.IllegalArgumentException: Mapped Statements collection

在spring+mybatis开发中遇到如下错误

HTTP Status 500 - Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException:

type Exception report

message Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException:

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for org.test.resources.mybatis.RouteMapper.findRoutes
### Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for org.test.resources.mybatis.RouteMapper.findRoutes
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:948)
	org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

调查代码发现org.test.UserMapper.findUsers没有找到org.test.UserMapper.findUsers，代码userMapper.xml是已经写过的 为什么没有找到呢，

通过查找代码发现 mybatis的配置文件中userMapper.xml没有配置才会出现上述错误

<mapper resource="org/test/resources/mybatis/userMapper.xml" />路径要写正确 完整写法如下：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> 
<configuration> 
    <typeAliases> 
        <typeAlias alias="UserEntity" type="org.test.bean.User" />
    </typeAliases> 
    <mappers>
        <mapper resource="org/test/resources/mybatis/userMapper.xml" />
    </mappers>
</configuration>

在dao中写法,包名加类名要注意写对
getSqlSession().selectList("org.test.resources.mybatis.UserMapper.findUsers");

userMapper.xml的写法：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 
<mapper namespace="org.test.resources.mybatis.UserMapper"> 
<resultMap type="UserEntity" id="userResultMap"> 
    <id property="id" column="id" />
    <result property="name" column="name" />
</resultMap> 
   
<select id="findUsers" resultType="UserEntity" resultMap="userResultMap">
    select id ,name from tb_users
</select>
   
</mapper>