1.PropertyPlaceholderConfigurer类
<beans> <bean id="configBean" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="location"><value>db.properties</value></property> </bean> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName"><value>${jdbc.driverClassName}</value></property> <property name="url"><value>${jdbc.url}</value></property> <property name="username"><value>${jdbc.username}</value></property> <property name="password"><value>${jdbc.password}</value></property> </bean> </beans>
db.properties文件 jdbc.driverClassName=org.hsqldb.jdbcDriver jdbc.url=jdbc:hsqldb:hsql://production:9002 jdbc.username=sa jdbc.password=root
2.PropertyOverrideConfigurer类
跟PropertyPlaceholderConfigurer功能一样,不过用法不一样.不用占位符,在属性文件中
直接定义属性的值,这样就允许有默认值
<beans> <bean id="configBean" class="org.springframework.beans.factory.config.PropertyOverrideConfigurer"> <property name="location"><value>db.properties</value></property> //ignoreResourceNotFound属性含义为在找不到属性文件时不会有异常抛出。 <property name="ignoreResourceNotFound" value="true"/> </bean> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName"><value>org.hsqldb.jdbcDriver</value></property> <property name="url"><value>jdbc:hsqldb:hsql://production:9002</value></property> <property name="username"><value>test</value></property> <property name="password"><value>123456</value></property> </bean> </beans>
db.properties文件 dataSource.username=admin dataSource.password=9527 在bean实例时,admin,9527将替代test,123456
3其他
1)如果需要引用多个属性,将configBean属性改为
<property name="locations"> <list> <value>db.properties</value> <value>db1.properties</value> </list> </property>
2)在ApplactionContext中是自动调用BeanFactoryPostProcessor接口的,如果要在BeanFactory中使用,必须手动添加:
XmlBeanFactory factory = new XmlBeanFactory(new FileSystemResource("beans.xml")); PropertyPlaceholderConfigurer cfg = new PropertyPlaceholderConfigurer(); cfg.setLocation(new FileSystemResource("jdbc.properties")); cfg.postProcessBeanFactory(factory);
Spring配置文件中的标签
//ignoreResourceNotFound属性含义为在找不到属性文件时不会有异常抛出。 <context:property-placeholder ignore-resource-not-found="true" location="classpath:hibernate/hibernate.properties" /> properties文件 test.jdbc.driverClassName=com.mysql.jdbc.Driver test.jdbc.url=jdbc:mysql://localhost:3306/test test.jdbc.username=root test.jdbc.password=root
1.这样一来就可以为spring配置的bean的属性设置值了,比如spring有一个jdbc数据源的类DriverManagerDataSource
在配置文件里这么定义bean:
<bean id="testDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="${test.jdbc.driverClassName}"/> <property name="url" value="${test.jdbc.url}"/> <property name="username" value="${test.jdbc.username}"/> <property name="password" value="${test.jdbc.password}"/> </bean>
2.甚至可以将${ }这种形式的变量用在spring提供的注解当中,为注解的属性提供值。