spring使用context-property-placeholder载不进属性问题

环境：spring3.1.1+mybatis3.2.8+mybatis-spring1.2.3

今天整合了SpringMVC + MyBatis，发现了一个问题，在这里做个记录，各位如果遇到相同的问题，可以参考下。

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1 2	<!-- 引入jdbc配置文件 -->  < context:property-placeholder  location = "classpath:prop/jdbc.properties"  />

引入文件时出现下面的错误，提示dataSource中的使用资源文件中key对应的value值没有引入进来。

### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class '${jdbc.driver}'] with root cause
java.lang.ClassNotFoundException: ${jdbc.driver}

首先确认jdbc.properties引入的路径没有问题。其次往下看。

解决案：

1. xml 头部将 default-autowire="byName"去掉。

2. 修改SqlSessionFactory。

将

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<!-- 创建SqlSessionFactory，同时指定数据源 -->  < bean  id = "sqlSessionFactory"  class = "org.mybatis.spring.SqlSessionFactoryBean" >       < property  name = "dataSource"  ref = "dataSource"  />       <!-- 自动扫描entity目录, 省掉Configuration.xml里的手工配置 -->      < property  name = "mapperLocations"  value = "classpath*:maper/*.map.xml"  /> </ bean >       <!-- DAO接口所在包名，Spring会自动查找其下的类 --> < bean  class = "org.mybatis.spring.mapper.MapperScannerConfigurer" >       < property  name = "basePackage"  value = "org.com.mars.dao"  /> </ bean >

改成：

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<!-- 创建SqlSessionFactory，同时指定数据源 -->  < bean  id = "mySqlSessionFactory"  class = "org.mybatis.spring.SqlSessionFactoryBean" >       < property  name = "dataSource"  ref = "dataSource"  />       <!-- 自动扫描entity目录, 省掉Configuration.xml里的手工配置 -->      < property  name = "mapperLocations"  value = "classpath*:maper/*.map.xml"  /> </ bean >       <!-- DAO接口所在包名，Spring会自动查找其下的类 --> < bean  class = "org.mybatis.spring.mapper.MapperScannerConfigurer" >       < property  name = "basePackage"  value = "org.com.mars.dao"  />      < property  name = "sqlSessionFactoryBeanName"  value = "mySqlSessionFactory"  />//value不能是ref，ref也会报错 </ bean >

这样，dataSource中就可以正常使用.properties文件中的key-value了。 

附：完整的配置文件，这个文件是用来完成spring和mybatis的整合的xml。

spring-resources.xml

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<? 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:p = "http://www.springframework.org/schema/p"       xmlns:context = "http://www.springframework.org/schema/context"       xmlns:tx = "http://www.springframework.org/schema/tx"       xmlns:aop = "http://www.springframework.org/schema/aop"      xsi:schemaLocation="       http://www.springframework.org/schema/beans        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd       http://www.springframework.org/schema/tx        http://www.springframework.org/schema/tx/spring-tx-3.0.xsd        http://www.springframework.org/schema/context        http://www.springframework.org/schema/context/spring-context-3.0.xsd      http://www.springframework.org/schema/aop             http://www.springframework.org/schema/aop/spring-aop-3.2.xsd"      default-autowire = "byName"  default-lazy-init = "false" >            <!-- 自动扫描组件，需要把controller去掉，否则影响事务管理 -->       < context:component-scan  base-package = "org.com.mars" >           < context:exclude-filter  type = "regex"               expression = "org.com.mars.controller.*"  />       </ context:component-scan >        <!-- 引入jdbc配置文件 -->       < context:property-placeholder  location = "classpath:prop/jdbc.properties"  />        <!-- (事务管理)transaction manager, use JtaTransactionManager for global tx -->       < bean  id = "transactionManager"           class = "org.springframework.jdbc.datasource.DataSourceTransactionManager" >           < property  name = "dataSource"  ref = "dataSource"  />       </ bean >            <!-- 声明式事务管理 -->      < aop:config >           < aop:advisor  pointcut = "execution(* org.com.mars.service..*.*(..))"               advice-ref = "myAdvice"  />       </ aop:config >       < tx:advice  id = "myAdvice"  transaction-manager = "transactionManager" >           < tx:attributes >               < tx:method  name = "find*"  propagation = "SUPPORTS"  read-only = "true"  />               < tx:method  name = "query*"  propagation = "SUPPORTS"  read-only = "true"  />               < tx:method  name = "list*"  propagation = "SUPPORTS"  read-only = "true"  />                   < tx:method  name = "create*"  propagation = "REQUIRED"  />               < tx:method  name = "save*"  propagation = "REQUIRED"  />               < tx:method  name = "modify*"  propagation = "REQUIRED"  />               < tx:method  name = "update*"  propagation = "REQUIRED"  />               < tx:method  name = "delete*"  propagation = "REQUIRED"  />                   < tx:method  name = "*"  propagation = "SUPPORTS"  read-only = "true"  />           </ tx:attributes >       </ tx:advice >             <!-- 创建SqlSessionFactory，同时指定数据源 -->       < bean  id = "mySqlSessionFactory"  class = "org.mybatis.spring.SqlSessionFactoryBean" >           < property  name = "dataSource"  ref = "dataSource"  />           <!-- 自动扫描entity目录, 省掉Configuration.xml里的手工配置 -->          < property  name = "mapperLocations"  value = "classpath*:maper/*.map.xml"  />      </ bean >            <!-- DAO接口所在包名，Spring会自动查找其下的类 -->      < bean  class = "org.mybatis.spring.mapper.MapperScannerConfigurer" >           < property  name = "basePackage"  value = "org.com.mars.dao"  />          < property  name = "sqlSessionFactoryBeanName"  value = "mySqlSessionFactory"  />      </ bean >            <!-- 可通过注解控制事务 -->       < tx:annotation-driven  />            <!-- 数据库连接池 -->      < bean  id = "dataSource"  class = "org.apache.commons.dbcp.BasicDataSource"          destroy-method = "close" >          <!-- Connection Info -->          < property  name = "driverClassName"  value = "${jdbc.driver}"  />          < property  name = "url"  value = "${jdbc.url}"  />          < property  name = "username"  value = "${jdbc.username}"  />          < property  name = "password"  value = "${jdbc.password}"  />            <!-- Connection Pooling Info -->          < property  name = "maxActive"  value = "${dbcp.maxActive}"  />          < property  name = "maxIdle"  value = "${dbcp.maxIdle}"  />          < property  name = "defaultAutoCommit"  value = "false"  />          <!-- 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 = "3600000"  />          <!-- 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 = "3600000"  />      </ bean >     </ beans >

jdbc.properties

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##jdbc jdbc.driver=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8 jdbc.username=root jdbc.password=root   #dbcp settings dbcp.initialSize=5 dbcp.maxActive=20 dbcp.maxIdle=10   jdbc.dbType=mysql

感谢热心的前辈技术分享！本文如有不正，请指出。

参考资料： 
http://www.oschina.net/question/188964_32305

以上。