如何查看Mybatis的报错（方法）

mybatis的报错看着我头疼，这个写给自己看。

类似于这种报错，我选中放到文本中来看，首先看前面的，在简化报错信息，比如下面的可以简化为：（见图下）

我知道有些人看英文头大，请忽视这些英文，把他（没错这一大段都是）看做一个一个符号分为：1、2、3、4，一个符号代表一个意思（不懂就百度翻译）。在逐步解决，具体见下图下的步骤：

 

1. 提取前面报错信息为errors：                  Error creating bean with name 'userController': Unsatisfied dependency expressed through field 'userDao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userDao' defined in file [D:\JAVA\JAVA2\Mybatis\target\classes\dao\UserDao.class]: Cannot resolve reference to bean 'sqlSessionFactory' while setting bean property 'sqlSessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [applicationContext.xml]: Invocation of init method failed; nested exception is org.springframework.core.NestedIOException: Failed to parse config resource: class path resource [mybatis-config.xml]; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'mybatis/UserMapper.xml'. Cause: java.lang.IllegalArgumentException: Mapped Statements collection already contains value for dao.UserDao.selectUserById. please check mybatis/UserMapper.xml and mybatis/UserMapper.xml
2. 进一步将Errors分为一个个Error看：  
3. Error creating bean with name 'userController': Unsatisfied dependency expressed through field 'userDao'; nested exception is org.springframework.beans.factory.BeanCreationException: 
4. Error creating bean with name 'userDao' defined in file [D:\JAVA\JAVA2\Mybatis\target\classes\dao\UserDao.class]: Cannot resolve reference to bean 'sqlSessionFactory' while setting bean property 'sqlSessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException:
5. Error creating bean with name 'sqlSessionFactory' defined in class path resource [applicationContext.xml]: Invocation of init method failed; nested exception is org.springframework.core.NestedIOException: Failed to parse config resource: class path resource [mybatis-config.xml]; nested exception is org.apache.ibatis.builder.BuilderException: 
6. 省略。。。
7. 从3看出事userDao，其实并没有什么用，4给出了sqlSessionFactory，5给出了[mybatis-config.xml];，往后看事越来越准确详细，可知道事[mybatis-config.xml]出现了问题，实际上后面还有，一直报到映射文件UserMapper.xml，时间情况也是该文件出现错误。

总结：错误分为父-》子-》孙，但建议将错误整合出来，一个个error往错误源推算。