spring+mybatis在读取配置文件时不识别占位符的问题。

本文讲述了在使用Spring+Mybatis搭建环境时遇到的一个问题,即配置文件中的${jdbc.username}占位符未被正确识别,导致无法连接数据库。作者通过分析异常信息和排查配置,发现是Spring的默认自动装配(byName)导致连接池没有正确初始化。移除该配置后,问题得到解决。参考链接:http://blog.youkuaiyun.com/wzlwlj/article/details/52057170

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最近有空闲时间了,想着整理下框架方面的东西。使用spring+mybatis自己手动搭建了个环境(没拷贝以前的配置,自己重新搭建),数据库使用的是properties文件,连接池使用的是druid,配好数据库后启动一直报错。

显示连接池把${jdbc.username}占位符当成字符串‘${jdbc.username}’了,无法连接数据库。在DataSource配置中直接写入信息却没错。

异常记录如下:

2017-06-17 09:10:32,077 [localhost-startStop-1] ERROR [com.alibaba.druid.pool.DruidDataSource] - dataSource init error
      java.sql.SQLException: ${jdbc.driverClassName}
	at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:520)
	at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:583)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeCustomInitMethod(AbstractAutowireCapableBeanFactory.java:1706)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1645)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:351)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1481)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1226)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:351)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
	at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:648)
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:145)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1143)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1046)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireByName(AbstractAutowireCapableBeanFactory.java:1244)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1194)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:120)
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:681)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:523)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4994)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5492)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1245)
	at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1895)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
	at java.util.concurrent.FutureTask.run(FutureTask.java:138)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.ClassNotFoundException: ${jdbc.driverClassName}
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:169)
	at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:518)
	... 64 more
2017-06-17 09:10:32,078 [localhost-startStop-1] INFO  [com.alibaba.druid.pool.DruidDataSource] - {dataSource-1} inited
      2017-06-17 09:10:32,080 [localhost-startStop-1] WARN  [org.springframework.web.context.support.XmlWebApplicationContext] - Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.mybatis.spring.mapper.MapperScannerConfigurer#0' defined in class path resource [applicationContext.xml]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionTemplate' defined in class path resource [applicationContext.xml]: Cannot resolve reference to bean 'sqlSory' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSory' defined in class path resource [applicationContext.xml]: Cannot resolve reference to bean 'dataSource' while setting bean property 'dataSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [applicationContext.xml]: Invocation of init method failed; nested exception is java.sql.SQLException: ${jdbc.driverClassName}
      2017-06-17 09:10:32,080 [localhost-startStop-1] DEBUG [org.springframework.beans.factory.support.DefaultListableBeanFactory] - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@3c0f3387: defining beans [md5PwdEncoder,userMngImpl,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,org.springframework.context.event.internalEventListenerProcessor,org.springframework.context.event.internalEventListenerFactory,org.springframework.beans.factory.config.PropertyPlaceholderConfigurer#0,dataSource,sqlSory,sqlSessionTemplate,org.mybatis.spring.mapper.MapperScannerConfigurer#0,logFilter,org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor,org.springframework.context.annotation.ConfigurationClassPostProcessor.enhancedConfigurationProcessor]; root of factory hierarchy
      2017-06-17 09:10:32,081 [localhost-startStop-1] ERROR [org.springframework.web.context.ContextLoader] - Context initialization failed
      org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.mybatis.spring.mapper.MapperScannerConfigurer#0' defined in class path resource [applicationContext.xml]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionTemplate' defined in class path resource [applicationContext.xml]: Cannot resolve reference to bean 'sqlSory' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSory' defined in class path resource [applicationContext.xml]: Cannot resolve reference to bean 'dataSource' while setting bean property 'dataSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [applicationContext.xml]: Invocation of init method failed; nested exception is java.sql.SQLException: ${jdbc.driverClassName}
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:120)
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:681)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:523)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4994)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5492)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1245)
	at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1895)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
	at java.util.concurrent.FutureTask.run(FutureTask.java:138)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:619)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionTemplate' defined in class path resource [applicationContext.xml]: Cannot resolve reference to bean 'sqlSory' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSory' defined in class path resource [applicationContext.xml]: Cannot resolve reference to bean 'dataSource' while setting bean property 'dataSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [applicationContext.xml]: Invocation of init method failed; nested exception is java.sql.SQLException: ${jdbc.driverClassName}
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:359)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
	at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:648)
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:145)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1143)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1046)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireByName(AbstractAutowireCapableBeanFactory.java:1244)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1194)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
	... 25 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSory' defined in class path resource [applicationContext.xml]: Cannot resolve reference to bean 'dataSource' while setting bean property 'dataSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [applicationContext.xml]: Invocation of init method failed; nested exception is java.sql.SQLException: ${jdbc.driverClassName}
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:359)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1481)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1226)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:351)
	... 39 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [applicationContext.xml]: Invocation of init method failed; nested exception is java.sql.SQLException: ${jdbc.driverClassName}
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1578)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:351)
	... 49 more
Caused by: java.sql.SQLException: ${jdbc.driverClassName}
	at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:520)
	at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:583)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeCustomInitMethod(AbstractAutowireCapableBeanFactory.java:1706)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1645)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
	... 56 more
Caused by: java.lang.ClassNotFoundException: ${jdbc.driverClassName}
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:169)
	at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:518)
	... 64 more

在放上我的配置文件:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd 
						http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd 
						http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd 
						http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd 
						http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"  default-autowire="byName"  default-lazy-init="true">

	<context:component-scan base-package="com.fb.tms">
		<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller" />
	</context:component-scan>
	<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <!-- 所有的应用程序全局变量配置,请集中在这里配置 -->
                <value>/WEB-INF/classes/jdbc.properties</value>
            </list>
        </property>
    </bean>
	<!-- 阿里 druid数据库连接池 -->
	<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close"> 
	  <property name="driverClassName" value="${jdbc.driverClassName}" /> 
	  <property name="url" value="${jdbc.url}" /> 
	  <property name="username" value="${jdbc.username}" /> 
	  <property name="password" value="${jdbc.password}" /> 
	  <!-- 配置初始化大小、最小、最大 --> 
	  <property name="initialSize" value="1" /> 
	  <property name="minIdle" value="1" /> 
	  <property name="maxActive" value="10" />
	  <!-- 配置获取连接等待超时的时间 --> 
	  <property name="maxWait" value="10000" />
	  <!-- 配置间隔多久才进行一次检测,检测需要关闭的空闲连接,单位是毫秒 --> 
	  <property name="timeBetweenEvictionRunsMillis" value="60000" />
	  <!-- 配置一个连接在池中最小生存的时间,单位是毫秒 --> 
	  <property name="minEvictableIdleTimeMillis" value="300000" />
	  <property name="testWhileIdle" value="true" />
	  <!-- 这里建议配置为TRUE,防止取到的连接不可用 --> 
	  <property name="testOnBorrow" value="true" /> 
	  <property name="testOnReturn" value="false" />
	  <!-- 打开PSCache,并且指定每个连接上PSCache的大小 --> 
	  <property name="poolPreparedStatements" value="true" /> 
	  <property name="maxPoolPreparedStatementPerConnectionSize" value="20" />
	  <!-- 这里配置提交方式,默认就是TRUE,可以不用配置 -->
	  <property name="defaultAutoCommit" value="true" />
	  <!-- 验证连接有效与否的SQL,不同的数据配置不同 --> 
	  <property name="validationQuery" value="select 1 " /> 
	  <property name="filters" value="stat" /> 
	  <property name="proxyFilters"> 
	   <list> 
	    <ref bean="logFilter" /> 
	   </list> 
	  </property> 
	 </bean>
	<!-- 配置mybatis -->
	<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    	<property name="dataSource" ref="dataSource" />
        <property name="configLocation" value="classpath:mybatis-config.xml"></property>
        <!-- mapper扫描 -->
        <property name="mapperLocations" value="classpath:com/fb/tms/sym/mapper/UserMapper.xml"></property>
    </bean>
	<!-- sql会话模版 -->
	<bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
		<constructor-arg ref="sqlSessionFactory" />
	</bean>
	<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
		<property name="basePackage" value="com.fb.tms.*.dao" />
		<property name="sqlSessionTemplateBeanName" value="sqlSessionTemplate" />
		<property name="annotationClass" value="org.springframework.stereotype.Repository" />
	</bean>
	
     <!-- 全局异常配置 end -->
	 <bean id="logFilter" class="com.alibaba.druid.filter.logging.Slf4jLogFilter"> 
	  	<property name="statementExecutableSqlLogEnable" value="false" /> 
	 </bean>
</beans>


感觉莫名其妙,检查一圈没发现问题。这可就把我这性子惹急了,抱着怼到底的心态开始了这个问题的抽丝剥茧之路。

说说我处理的思路:

一、明确问题

通过读取异常信息,分析得知是spring配置文件无法识别占位符的内容

二、分析有可能出现问题的地方

1.配置文件本身有错

2.数据库连接池有错

3.spring读取配置文件有错

4.mybatis和spring整合时获取数据库连接有错

三、依次排除问题

怀疑1和二通过简单置换后很容易排除掉了。

怀疑3通过spring的官方文档和百度以及之前项目的配置也被排除掉。

那么只剩下怀疑的第4个点了。查阅相关资料后却没发现有啥大的问题。

于是在源码上断点,发现一个问题。获取properties的spring类在报错误之前没被初始化!!!通过检查错误信息的时间也确定了这点。

由此看来应该是mybatis在使用数据库连接池时,连接池一直没有被初始化。期间也怀疑过是不是spring中bean加载顺序导致的,可是查询得知spring是按顺序加载的。

那么现在问题就变成了mybatis调用数据库连接池初始化的问题了。

经过查询看到一篇文章对我启发很大,检查过后发现问题确实如此。给出链接http://blog.youkuaiyun.com/wzlwlj/article/details/52057170

检查自己配置文件发现,在spring头部配置了 default-autowire="byName"  去掉后一切正常。 


<think>好的,我现在要回答用户的问题:“在任意注解中都可通过占位符读取配置文件占位符吗?”首先,我需要确认用户的问题核心。用户想知道是否在所有的注解中都可以使用像${...}这样的占位符读取配置文件中的值。 首先,我应该回顾一下Spring框架中占位符的使用机制。记得在Spring中,处理占位符的主要组件是PropertySourcesPlaceholderConfigurer,它负责解析${...}表达式。但注解中的占位符解析是否普遍适用呢? 接下来,我需要区分同类型的注解。Spring的原生注解,比如@Value、@Bean、@ConfigurationProperties等,是明确支持占位符的。但是第三方库或自定义的注解是否支持呢?这可能取决于它们是否集成了Spring的Environment或者相关的解析器。 然后,需要考虑框架的版本。例如,Spring Boot的同版本可能会有同的行为,但用户的问题比较通用,可能需要涉及版本差异,但可以提到可能存在例外情况。 需要举例说明哪些注解支持,哪些支持。例如,@Value肯定支持,而JPA的@Table(name = "${entity.table}")可能在某些情况下支持,或者需要额外的配置。 还要提到条件注解,如@ConditionalOnProperty,它们是否支持占位符?可能支持,因为它们可能直接读取属性名称而是解析后的值。 另外,需要强调占位符解析的条件,比如是否启用了PropertySourcesPlaceholderConfigurer,或者配置是否正确。例如,如果没有正确配置,即使注解支持,占位符也无法解析。 可能用户在使用某些注解遇到了占位符无法解析的问题,想知道是否是普遍情况。因此,回答中需要明确说明,并非所有注解都支持,取决于注解的实现方式。 还要提到自定义注解的处理方式,如果用户自己定义的注解想要支持占位符,可能需要通过AOP或者后置处理器来实现,这属于高级用法。 总结起来,回答的结构应该是:先说明大部分Spring原生注解支持,但并非所有注解都支持,具体取决于注解的设计和实现。然后分点讨论支持的情况、支持的情况,以及如何验证和解决问题。</think>--- 在Spring框架中,**并非所有注解都支持通过`${}`占位符直接读取配置文件值**。是否支持取决于注解的实现机制和Spring占位符解析的支持层级。以下是详细分类说明: --- ### 一、支持占位符的注解类型 #### 1. Spring原生属性注入注解 | 注解类型 | 示例代码 | 支持原理 | |-----------------------|--------------------------------------------------------------------------|--------------------------------------------------------------------------| | `@Value` | `@Value("${server.port}")` | 底层通过`PropertySourcesPlaceholderConfigurer`解析 | | `@Configuration`中的Bean定义 | `@Bean(name = "${bean.name}")` | Spring容器在创建Bean自动解析 | | `@Conditional`系列 | `@ConditionalOnProperty("feature.enabled")` | 直接读取配置值,但注意*支持嵌套占位符* | #### 2. Spring Boot Starter相关注解 ```java // RabbitMQ配置 @RabbitListener(bindings = @QueueBinding( exchange = @Exchange(name = "${mq.exchange}") // 支持占位符 )) // MyBatis配置 @MapperScan(basePackages = "${mybatis.scan.packages}") // 支持 ``` #### 3. 配置绑定注解 ```java @ConfigurationProperties(prefix = "app") public class AppConfig { private String endpoint; // 自动绑定app.endpoint } ``` --- ### 二、支持占位符的常见场景 #### 1. JPA实体映射注解 ```java @Entity @Table(name = "${entity.table.name}") // ❌ 无法解析,Hibernate会处理占位符 public class UserEntity { ... } ``` #### 2. Validation校验注解 ```java @Size(max = "${validation.max-size}") // ❌ javax.validation直接读取字面值 private String data; ``` #### 3. 第三方框架自定义注解 ```java @ThirdPartyAnnotation(configFile = "${custom.path}") // ❌ 除非框架显式支持Spring环境 ``` --- ### 三、验证占位符是否生效的方法 #### 方法1:启动检查日志 若占位符未被解析,会抛出: ```log Could not resolve placeholder 'xxx' in value "${xxx}" ``` #### 方法2:运行检查 ```java @RestController public class DebugController { @Value("${debug.property}") private String testProp; @GetMapping("/check") public String check() { return "Property value: " + testProp; // 暴露配置值验证 } } ``` --- ### 四、强制启用占位符解析的特殊技巧 #### 方案1:自定义属性解析器(适用于支持的注解) ```java public class CustomAnnotationProcessor implements BeanPostProcessor { @Autowired private Environment env; @Override public Object postProcessBeforeInitialization(Object bean, String beanName) { // 通过反射修改注解值 Field[] fields = bean.getClass().getDeclaredFields(); for (Field field : fields) { if (field.isAnnotationPresent(ThirdPartyAnnotation.class)) { ThirdPartyAnnotation anno = field.getAnnotation(ThirdPartyAnnotation.class); String resolvedValue = env.resolvePlaceholders(anno.configFile()); // 动态修改注解值(需使用字节码增强库) } } return bean; } } ``` #### 方案2:间接注入(通用解决方案) ```java @Configuration public class IndirectConfig { @Value("${dynamic.value}") private String dynamicValue; @Bean public ThirdPartyComponent thirdPartyComponent() { return new ThirdPartyComponent(dynamicValue); // 通过构造函数传递 } } ``` --- ### 五、支持层级对照表 | 注解类型 | 占位符支持 | 是否需要额外配置 | |-------------------------|------------|---------------------------| | Spring原生注解 | ✅ | 自动生效 | | Spring Cloud注解 | ✅ | 自动生效 | | JSR-330/JSR-250注解 | ❌ | 可直接使用 | | JPA/Hibernate注解 | ❌ | 需自定义拦截器 | | 自定义注解 | ❌ | 需实现`BeanPostProcessor` | --- ### 总结 1. **Spring核心注解**:大部分支持占位符解析(@Value、@Bean等) 2. **第三方注解**:默认支持,需要特殊处理 3. **验证关键**:通过启动日志和运行检查确认解析结果 4. **扩展方案**:可通过环境变量间接传递或使用后处理器增强 建议在无法确定注解是否支持占位符,优先查阅对应框架的官方文档或通过实验验证。
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