先贴一段报错信息:
前面的都不是很重要,看最后灰色标注的那段。。。。
严重: 异常将上下文初始化事件发送到类的侦听器实例.[org.springframework.web.context.ContextLoaderListener]
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionfactory' defined in class path resource [applicationContext-dao.xml]: Invocation of init method failed; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [D:\apache-tomcat-8.5.46\webapps\ssm_blog\WEB-INF\classes\org\blog\dao\FriendMapper.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: java.lang.IllegalArgumentException: Mapped Statements collection already contains value for org.blog.dao.FriendMapper.searchFriend
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1566)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:743)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4699)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5165)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1412)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1402)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [D:\apache-tomcat-8.5.46\webapps\ssm_blog\WEB-INF\classes\org\blog\dao\FriendMapper.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: java.lang.IllegalArgumentException: Mapped Statements collection already contains value for org.blog.dao.FriendMapper.searchFriend
at org.mybatis.spring.SqlSessionFactoryBean.buildSqlSessionFactory(SqlSessionFactoryBean.java:466)
at org.mybatis.spring.SqlSessionFactoryBean.afterPropertiesSet(SqlSessionFactoryBean.java:340)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1625)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1562)
... 21 more
Caused by: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: java.lang.IllegalArgumentException: Mapped Statements collection already contains value for org.blog.dao.FriendMapper.searchFriend
at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:120)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.parse(XMLMapperBuilder.java:92)
at org.mybatis.spring.SqlSessionFactoryBean.buildSqlSessionFactory(SqlSessionFactoryBean.java:464)
... 24 more
Caused by: java.lang.IllegalArgumentException: Mapped Statements collection already contains value for org.blog.dao.FriendMapper.searchFriend
at org.apache.ibatis.session.Configuration$StrictMap.put(Configuration.java:782)
at org.apache.ibatis.session.Configuration$StrictMap.put(Configuration.java:754)
at org.apache.ibatis.session.Configuration.addMappedStatement(Configuration.java:578)
at org.apache.ibatis.builder.MapperBuilderAssistant.addMappedStatement(MapperBuilderAssistant.java:288)
at org.apache.ibatis.builder.xml.XMLStatementBuilder.parseStatementNode(XMLStatementBuilder.java:107)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.buildStatementFromContext(XMLMapperBuilder.java:135)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.buildStatementFromContext(XMLMapperBuilder.java:128)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:118)
... 26 more
当出现Mapped Statements collection already contains value for。。。。。(意思大概:xxx 在statements 执行语句的集合中已经存在了。。。(塑料英语,大佬轻拍))
这种报错时
错误原因有:
1.mapper中存在id重复的值
2.mapper中的parameterType或resultType为空。
例如:<select id="findProductById" parameterType=" "> </select>
3. 在使用@Select等注解的情况下,方法名即为mapper的id,重载的方法会报这个错。
4. mapper复制 忘了改namespace指向的类,所以两个mapper指向同一个mapper,所以报了这个错。
5.sqlMapperConfig.xml与application-dao.xml(文件名不一定相同,我在这个文件中主要配置的是,sqlSessionFactory放入IOC容器和扫描mapper包下的文件,并将mapper接口的实现类放入容器)中
例如:
<mappers>
<package name="org.blog.dao"/>
</mappers>
<package name="org.blog.dao"/>
</mappers>
和
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="org.blog.dao"></property>
</bean>
<property name="basePackage" value="org.blog.dao"></property>
</bean>
重复了,删掉一个就可以了。。。。