问题描述：
使用mybatis时这个错是一个很常见的错误了，这个报错也很明显就是找不到某某的mapper.xml文件，首先我们应该清楚mapper.xml文件会在我们编译时被加载到（复制一份过去）对应的class路径下，出现这个错的根本原因在于在程序执行时，去对应路径下找这个mapper文件，却找不到，就会报出这个错误，下面是错误详情：

### The error may exist in com/cheng/dao/SupplierMapper.xml
### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: java.io.IOException: Could not find resource com/cheng/dao/SupplierMapper.xml
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
	at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:80)
	at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:64)
	at com.cheng.utils.MybatisUtil.<clinit>(MybatisUtil.java:24)
	... 26 more
Caused by: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: java.io.IOException: Could not find resource com/cheng/dao/SupplierMapper.xml
	at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:122)
	at org.apache.ibatis.builder.xml.XMLConfigBuilder.parse(XMLConfigBuilder.java:99)
	at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:78)
	... 28 more
Caused by: java.io.IOException: Could not find resource com/cheng/dao/SupplierMapper.xml
	at org.apache.ibatis.io.Resources.getResourceAsStream(Resources.java:114)
	at org.apache.ibatis.io.Resources.getResourceAsStream(Resources.java:100)
	at org.apache.ibatis.builder.xml.XMLConfigBuilder.mapperElement(XMLConfigBuilder.java:375)
	at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:120)
	... 30 more


Process finished with exit code -1

问题分析：
问题原因其实已经知道了，就是因为在编译出来的class文件下找不到这个文件，那为什么编译时明明存在，编程成的class文件下却没有呢，其实原因在于maven，maven项目在编译properties与xml等文件时有时可能并不会将它们编译到对应的class路径里面，这时就需要我们手动指定将这些文件导出到class文件目录下。
问题解决：
在pom.xml中添加以下内容，告诉maven将xml、properties等文件导出到class文件目录下，问题解决，需要说的是若是父子工程，则只需要在父工程中添加如下配置即可（plugin中配置的jdk版本请忽略）。

<build>
        <plugins>
            <!--指定当前工程jdk的版本-->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
        <resources>
            <!--导出静态资源文件，防止xml配置文件未加载-->
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>