01

問題描述

今天在寫mybatis和spring整合的時候，出現了個問題，其實也沒有多難，就是自己沒有仔細看，特此記錄一下。

報錯問題如下：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'empService'?defined in?class path resource [applicationContext.xml]: Initialization of bean failed; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type?'org.mybatis.spring.mapper.MapperScannerConfigurer'?to required type?'org.dao.EmpDaoMapper'?for?property 'empDao'; nested exception is java.lang.IllegalStateException: Cannot convert value of type?[org.mybatis.spring.mapper.MapperScannerConfigurer] to required type?[org.dao.EmpDaoMapper] for?property 'empDao': no matching editors or conversion strategy foundat org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:529)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:293)at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:191)at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:636)at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:934)at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)at org.test.TestMain.before(TestMain.java:21)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:606)at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)at org.junit.runners.ParentRunner.run(ParentRunner.java:236)at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) Caused by: org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type?'org.mybatis.spring.mapper.MapperScannerConfigurer'?to required type?'org.dao.EmpDaoMapper'?for?property 'empDao'; nested exception is java.lang.IllegalStateException: Cannot convert value of type?[org.mybatis.spring.mapper.MapperScannerConfigurer] to required type?[org.dao.EmpDaoMapper] for?property 'empDao': no matching editors or conversion strategy foundat org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:464)at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:495)at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:489)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1465)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1424)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1160)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)... 34 more Caused by: java.lang.IllegalStateException: Cannot convert value of type?[org.mybatis.spring.mapper.MapperScannerConfigurer] to required type?[org.dao.EmpDaoMapper] for?property 'empDao': no matching editors or conversion strategy foundat org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:267)at org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:449)... 40 more

下面是spring的所有配置文件信息：

配置數據源信息：

<!-- 配置數據源 --><bean?id="dataSource"?class="org.apache.commons.dbcp.BasicDataSource"><property?name="driverClassName"?value="com.mysql.jdbc.Driver"></property><property?name="url"?value="jdbc:mysql://localhost:3306/schooldb"></property><property?name="username"?value="root"></property><property?name="password"?value="root"></property></bean>

配置SqlSessionFactory信息，以及加載數據源：

<!-- 加載數據源 --><bean?id="sqlSessionFactory"?class="org.mybatis.spring.SqlSessionFactoryBean"><property?name="dataSource"?ref="dataSource"></property><!-- 配置mapper屬性 --><property?name="mapperLocations"><list><value>classpath:org/dao/*/*.xml</value></list></property><!-- 配置mybatis配置文件 --><property?name="configLocation"?value="classpath:mybatis-config.xml"></property></bean>

使用MapperScannerConfigurer注入映射器：

<!-- 使用MapperScannerConfigurer --><bean?id="empDao"?class="org.mybatis.spring.mapper.MapperScannerConfigurer"><property?name="basePackage"?value="org.dao"></property></bean>

下面就是配置Service層：

<bean id="empService"?class="org.service.impl.EmpServiceImpl"><property?name="empDao"?ref="empDao"></property></bean>

問題就出在“配置Service層”這一步，原來在未使用MapperScannerConfigurer的時候，程序是可以正常跑起來的，但是加上MapperScannerConfigurer，程序就報錯，找了好半天，終于發現，原來粗心的將對象名寫錯了，下面是問題的解決方式：

02

解決問題

更正MapperScannerConfigurer注入映射器和empService注入映射器，代碼如下：

<!-- 使用MapperScannerConfigurer --><bean??class="org.mybatis.spring.mapper.MapperScannerConfigurer"><property?name="basePackage"?value="org.dao"></property></bean><bean?id="empService"?class="org.service.impl.EmpServiceImpl"><property?name="empDao"?ref="empDaoMapper"></property></bean>

然后運行項目，正常執行：

03

分析問題

當我們使用MapperScannerConfigurer注入映射器時，可以不用Mapper的實現類，但是Mapper的接口名必須要與所對應的SQL映射文件名一模一樣，且接口中的方法名需與SQL映射文件的id名相同。

通過MapperScannerConfigurer可以批量生成映射器實現，映射器被注冊到Spring的容器時，spring會自動根據其接口名給其命名，默認規則是首字母小寫的非完全限定名。比如上面代碼中的接口名為EmpDaoMapper,那默認命名就是empDaoMapper,原來在ref引入對象的時候，寫的是empDao，所以就報錯。改成其默認的命名empDaoMapper問題解決。

希望大家在整合框架的時候，能認真細心，避免出現沒必要的bug，耽誤時間。

辣椒醬，了解下唄~

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