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Spring 利用PropertyPlaceholderConfigurer占位符

 
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1.Spring的框架中,org.springframework.beans.factory.config.PropertyPlaceholderConfigurer类可以将.properties(key/value形式)文件中一些动态设定的值(value),在XML中替换为占位该键($key$)的值,.properties文件可以根据客户需求,自定义一些相关的参数,这样的设计可提供程序的灵活性。

2.在Spring中,使用PropertyPlaceholderConfigurer可以在XML配置文件中加入外部属性文件,当然也可以指定外部文件的编码,如:
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location">
<value>conf/sqlmap/jdbc.properties</value>
</property>
<property name="fileEncoding">
<value>UTF-8</value>
</property>
</bean>
当然也可以引入多个属性文件,如:
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>/WEB-INF/mail.properties</value>
<value>classpath: conf/sqlmap/jdbc.properties</value>//注意这两种value值的写法
</list>
</property>
</bean>

基本的使用方法是:

Xml代码
<bean id="propertyConfigurerForAnalysis" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location">
<value>classpath:/spring/include/dbQuery.properties</value>
</property>
<property name="fileEncoding">
<value>UTF-8</value>
</property>

</bean>

其中classpath是引用src目录下的文件写法。



当存在多个Properties文件时,配置就需使用locations了:

Xml代码
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:/spring/include/jdbc-parms.properties</value>
<value>classpath:/spring/include/base-config.properties</value>
<value>classpath*:config/jdbc.properties</value>
</list>
</property>
</bean>



接下来我们要使用多个PropertyPlaceholderConfigurer来分散配置,达到整合多工程下的多个分散的Properties文件,其配置如下
Xml代码

<bean id="propertyConfigurerForProject1" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="order" value="1" />
<property name="ignoreUnresolvablePlaceholders" value="true" />
<property name="location">
<value>classpath:/spring/include/dbQuery.properties</value>
</property>
</bean>



Xml代码

<bean id="propertyConfigurerForProject2" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="order" value="2" />
<property name="ignoreUnresolvablePlaceholders" value="true" />
<property name="locations">
<list>
<value>classpath:/spring/include/jdbc-parms.properties</value>
<value>classpath:/spring/include/base-config.properties</value>
</list>
</property>
</bean> 其中order属性代表其加载顺序,而ignoreUnresolvablePlaceholders为是否忽略不可解析的Placeholder,如配置了多个PropertyPlaceholderConfigurer,则需设置为true



3.譬如,jdbc.properties的内容为:
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost/mysqldb?useUnicode=true&amp;characterEncoding=UTF-8&amp;zeroDateTimeBehavior=round;
jdbc.username=root
jdbc.password=123456

4.那么在spring配置文件中,我们就可以这样写:
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath: conf/sqlmap/jdbc.properties </value>
</list>
</property>
</bean>

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" 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}" />
</bean>


5.这样,一个简单的数据源就设置完毕了。可以看出:PropertyPlaceholderConfigurer起的作用就是将占位符指向的数据库配置信息放在bean中定义的工具。




Java代码 收藏代码
  1. <!--dataSource-->
  2. <beanid="dataSource"
  3. class="org.springframework.jdbc.datasource.DriverManagerDataSource">
  4. <propertyname="driverClassName"
  5. value="${jdbc.driverClassName}"/>
  6. <propertyname="url"value="${jdbc.url}"/>
  7. <propertyname="username"value="${jdbc.username}"/>
  8. <propertyname="password"value="${jdbc.password}"/>
  9. </bean>
  10. <!--sessionFactory-->
  11. <beanid="sessionFactory"
  12. class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
  13. <propertyname="dataSource"ref="dataSource"/>
  14. <propertyname="mappingResources">
  15. <list>
  16. <value>cn/xg/hibernate/spring/User.hbm.xml</value><!--这里的映射路径问题,这种方法只能一个一个加-->
  17. <value>cn/xg/hibernate/spring/Group.hbm.xml</value>
  18. </list>
  19. <!--加载一个路径下的*.hbm.xml文件方法:
  20. <propertyname="mappingDirectoryLocations">
  21. <list>
  22. <value>classpath:/cn/xg/spring/model</value>
  23. </list>
  24. </property>
  25. -->
  26. </property>
  27. <propertyname="hibernateProperties">
  28. <props>
  29. <propkey="hibernate.dialect">
  30. ${hibernate.dialect}
  31. </prop>
  32. <propkey="hibernate.show_sql">true</prop>
  33. </props>
  34. </property>
  35. </bean>
  36. <!--DAO实现类extendsHibernateDaoSupport,注入sessionFactory-->
  37. <beanid="userMgrImpl"class="cn.xg.hibernate.spring.UserMgrImpl">
  38. <propertyname="sessionFactory"ref="sessionFactory"/>
  39. </bean>
  40. <beanid="groupMgrImpl"
  41. class="cn.xg.hibernate.spring.GroupMgrImpl">
  42. <propertyname="sessionFactory"ref="sessionFactory"/>
  43. <propertyname="userImpl"ref="userMgrImpl"/>
  44. <propertyname="transactionTemplate"ref="transactionTemplate"/>
  45. </bean>
  46. <!--事务管理-->
  47. <beanid="transactionManager"
  48. class="org.springframework.orm.hibernate3.HibernateTransactionManager">
  49. <propertyname="sessionFactory"ref="sessionFactory"/>
  50. </bean>
  51. <!--编程式事务的写法:向Dao实现类中注入transactionTemplate,调动其execute()方法,接口回调newTransactionCallback()-->
  52. <beanid="transactionTemplate"class="org.springframework.transaction.support.TransactionTemplate">
  53. <propertyname="transactionManager"ref="transactionManager"/>
  54. </bean>
  55. <!--声时式事务第一种写法-->
  56. <!--
  57. <beanid="groupMgr"
  58. class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
  59. <propertyname="transactionManager"ref="transactionManager"/>
  60. <propertyname="target"ref="groupMgrImpl"/>
  61. <propertyname="transactionAttributes">
  62. <props>
  63. <propkey="add*">PROPAGATION_REQUIRED</prop>
  64. <propkey="get*">PROPAGATION_REQUIRED</prop>
  65. <propkey="*">readOnly</prop>
  66. </props>
  67. </property>
  68. </bean>
  69. -->
  70. <!--声时式事务第二种写法-->
  71. <!--事务的传播特性
  72. <tx:adviceid="txAdvice">
  73. <tx:attributes>
  74. <tx:methodname="add*"propagation="REQUIRED"/>
  75. <tx:methodname="get*"propagation="REQUIRED"/>
  76. <tx:methodname="*"read-only="true"/>
  77. </tx:attributes>
  78. </tx:advice>
  79. <aop:config>
  80. <aop:advisorpointcut="execution(*cn.xg.hibernate.spring.*.*(..))"
  81. advice-ref="txAdvice"/>
  82. </aop:config>
  83. -->
  84. </beans>
  85. jdbc.properties
  86. jdbc.driverClassName=com.mysql.jdbc.Driver
  87. jdbc.url=jdbc:mysql://localhost:3306/数据库名
  88. jdbc.username=数据库用户名
  89. jdbc.password=数据库密码
  90. hibernate.dialect=org.hibernate.dialect.MySQLDialect(方言.这里是MySql)
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