Spring屬性佔位符PropertyPlaceholderConfigurer的使用

一、一個簡單的Demo

1.一、建立conf.xml

<?xml version= "1.0" encoding= "UTF-8"?>
<!DOCTYPE beans PUBLIC  "-//SPRING//DTD BEAN//EN"  "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <bean id= "propertyConfigurer"   class= "org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <!-- 
        使用location屬性定義單個配置文件
        <property name= "location">
            <value>classpath:/com/zsw/config/jdbc.properties</value>
        </property>
         -->
  
  <!-- 使用locations屬性定義多個配置文件 -->
  <property name= "locations">
     <list>
        <value>classpath:/com/zsw/config/jdbc.properties</value>
     </list>
  </property> 
    </bean>
    <bean id= "dataSource"   class= "org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name= "url">
            <value>${database.url}</value>
        </property>
        <property name= "driverClassName">
            <value>${database.driver}</value>
        </property>
        <property name= "username">
            <value>${database.user}</value>
        </property>
        <property name= "password">
            <value>${database.password}</value>
        </property>
    </bean>
</beans>

1.2.建立jdbc.properties文件

database.driver=com.mysql.jdbc.Driver
database.url=jdbc:mysql: //localhost:3306/right?useUnicode=true&autoReconnect=true&characterEncoding=UTF-8
database.user=root
database.password=root
jdbc.pool.c3p0.acquire_increment=2
jdbc.pool.c3p0.max_size=20
jdbc.pool.c3p0.min_size=2
jdbc.pool.c3p0.preferred_test_query='SELECT 1'
jdbc.pool.c3p0.idle_connection_test_period=18000
jdbc.pool.c3p0.max_idle_time=25000

1.3.建立Config.java

package com.zsw.config;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.core.io.FileSystemResource;
import org.springframework.jdbc.datasource.DriverManagerDataSource;

public  class Config {
      public  static  void main( String[] args) {
         XmlBeanFactory factory =  new XmlBeanFactory( new FileSystemResource( "src/com/zsw/config/conf.xml"));
          // 若是要在BeanFactory中使用，bean factory post-processor必須手動運行:
         PropertyPlaceholderConfigurer cfg =  new PropertyPlaceholderConfigurer();
         cfg.setLocation( new FileSystemResource( "src/com/zsw/config/jdbc.properties"));
         cfg.postProcessBeanFactory(factory);
         DriverManagerDataSource dataSource = (DriverManagerDataSource) factory.getBean( "dataSource");
//         System.out.println(dataSource.getDriverClassName());
         
         
         System.out.println(dataSource.getUsername());
          // 注意，ApplicationContext可以自動辨認和應用在其上部署的實現了BeanFactoryPostProcessor的bean。這就意味着，當使用ApplicationContext的時候應用PropertyPlaceholderConfigurer會很是的方便。因爲這個緣由，建議想要使用這個或者其餘bean
          // factory postprocessor的用戶使用ApplicationContext代替BeanFactroy。
         ApplicationContext context =  new ClassPathXmlApplicationContext( "com/zsw/config/conf.xml");
         DriverManagerDataSource dataSource2 = (DriverManagerDataSource) context.getBean( "dataSource");
         System.out.println(dataSource2.getUsername());
     }
 
}

 

2.Spring中PropertyPlaceholderConfigurer多種配置方式

2.1配置單個Properties文件

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

其中classpath是引用src目錄下的文件寫法。

2.2 當存在多個Properties文件時，配置就需使用locations了：

  

   
  < 
 
   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>         < 
 
   /list>     < 
 
   /property> < 
 
   /bean> 

  

 

2.三、接下來咱們要使用多個PropertyPlaceholderConfigurer來分散配置，達到整合多工程下的多個分散的Properties 文件，其配置以下：

<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>

 

< 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屬性表明其加載順序，而ignoreUnresolvablePlaceholders爲是否忽略不可解析的 Placeholder，如配置了多個PropertyPlaceholderConfigurer，則需設置爲true