java - Spring PropertyPlaceholderConfigurer load from DB

Question

Is it possible to load properties from DB with Custom Spring PropertyPlaceholderConfigurer? and is it also possible that datasource provided to custom PropertyPlaceholderConfigurer use specific property file in classpath?

I could not find satisfied answer from following links?

http://www.mkyong.com/spring/spring-propertyplaceholderconfigurer-example/ http://www.codeproject.com/Articles/28893/Loading-Application-Properties-from-a-Database PropertyPlaceholderConfigurer to look for DB values and use properties file as fallback

Answer 1

Spring Context XML

<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"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <bean
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="ignoreUnresolvablePlaceholders" value="true"/>
        <property name="ignoreResourceNotFound" value="false"/>
        <property name="order" value="1" />
        <property name="locations">
            <list>
                <value>classpath:db.properties</value>
            </list>
        </property>
    </bean>

 <bean id="dataSourceimos" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
        <property name="driverClass"><value>${imosdb.driver}</value></property>
        <property name="jdbcUrl"><value>${imosdb.url}</value></property>
        <property name="user"><value>${imosdb.username}</value></property>
        <property name="password"><value>${imosdb.password}</value></property>
        <property name="initialPoolSize"><value>${imosdb.initial_pool_size}</value></property>
        <property name="maxPoolSize"><value>${imosdb.max_pool_size}</value></property>
        <property name="minPoolSize"><value>${imosdb.min_pool_size}</value></property>
        <property name="acquireIncrement" value="1"/>
        <property name="acquireRetryAttempts" value="1"/>
        <property name="idleConnectionTestPeriod" value="30"/>
        <property name="preferredTestQuery" value="select 1 from dual"/>
        <property name="checkoutTimeout" value="5000"/>
        <property name="maxAdministrativeTaskTime" value="120"/>
        <property name="numHelperThreads" value="10"/>
    </bean>

    <bean
        class="com.ahmetk.property.DbPropertySourcesPlaceholderConfigurer">
        <property name="ignoreUnresolvablePlaceholders" value="true"/>
        <property name="ignoreResourceNotFound" value="true"/>
        <property name="order" value="2" />
        <property name="placeholderPrefix" value="${" />
        <property name="placeholderSuffix" value="}" />
        <property name="dataSourceName" value="dataSourceimos" />

        <property name="locations">
            <list>
                <value>classpath:static.properties</value>
                <value>file:static.properties</value>
            </list>
        </property>

    </bean>

    <context:component-scan base-package="com.mkyong.rest" />

    <bean id="transactionBo" class="com.mkyong.transaction.impl.TransactionBoImpl" />
    <bean id="cacheServiceInterface" class="com.ttech.tims.imos.data.cache.CacheServiceImpl" />
    <bean id="iCacheService" class="com.ttech.tims.imos.data.cache.impl.CacheService" />

</beans>

Java PlaceholderClass

import java.util.Properties;

import javax.sql.DataSource;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;


public class DbPropertySourcesPlaceholderConfigurer extends PropertyPlaceholderConfigurer 
{
   private static final String DEFAULT_DATASOURCENAME = "dataSource";
   private static final String DEFAULT_DBTABLENAME = "property";
   private static final String DEFAULT_DBKEYCOLUMNNAME = "key";
   private static final String DEFAULT_DBVALUECOLUMNNAME = "value";
   String dataSourceName;
   String dbTableName;
   String dbKeyColumnName;
   String dbValueColumnName;
   @Override
   public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException
   {

      DataSource dataSource = (DataSource) beanFactory.getBean(getDataSourceName());
     // DbProperties dbProps = new DbProperties(dataSource);
      final Properties dbProps = new Properties();
      dbProps.put("app.version", "v3");
      setProperties(dbProps);
      super.postProcessBeanFactory(beanFactory);
   }

   public String getDataSourceName() {
      return dataSourceName==null?DEFAULT_DATASOURCENAME:dataSourceName;
   }

   public void setDataSourceName(String dataSourceName) {
      this.dataSourceName = dataSourceName;
   }


}

Special thanks to writer of following pages.

http://ykchee.blogspot.com.tr/2012/09/spring-31-loading-properties-for-xml.html

http://blog.javaforge.net/post/31720600427/configuring-spring-based-web-application-from-database

http://www.javacodegeeks.com/2012/11/spring-3-1-loading-properties-for-xml-configuration-from-database.html