在确定xml的namespace 、resultType都无误后，可以查看生成的target文件夹下mapper下是否有xml文件夹，没有在pom文件中添加
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
<include>**/*.json</include>
</includes>
</resource>
</resources>