Wiring a bean from a database

[blfinche]

I am wiring a bean with the port values from our developer machines. I would like to retrieve the value from a database. I think a custom property editor would be the right way to accomplish this. Is there another way of accomplishing this?

Thanks,
Bobby

[Alarmnummer]

You could use a PropertyPlaceholderConfigurer to externalize the properties. And there is another (spring) project that has created a few implementation (not only property files, but database access aswel), but I can`t find the link.

[hay7777]

Does anyone know where this is? I need it too!

cheers,

David

[wpoitras]

Here is a configuration file which loads properties from a database using Apache Commons Configuration (whose connection properties are loaded from db.properties). Since I'm using two PropertyPlaceholderConfigurer, I needed to use a different placeholderPrefix for the file based one. That way the properties in the rest of the context uses normal syntax:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http&#58;//www.springframework.org/dtd/spring-beans.dtd">
<beans>
	<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
		<property name="location" value="db.properties"/>
		<property name="placeholderPrefix" value="$&#123;init&#58;"/>
	</bean>
	
	<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
		<property name="properties">
			<bean factory-class="org.apache.commons.configuration.ConfigurationConversion"
	      		  factory-method="getProperties">
		  		<constructor-arg>
					<bean class="org.apache.commons.configuration.DatabaseConfiguration">
				  		<constructor-arg>
			   				<bean class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
						      <property name="driverClassName" value="$&#123;init&#58;jdbc.driver&#125;"/>
						      <property name="url" value="$&#123;init&#58;jdbc.url&#125;"/>
						      <property name="username" value="$&#123;init&#58;jdbc.username&#125;"/>
						      <property name="password" value="$&#123;init&#58;jdbc.password&#125;"/>
						    </bean> 	
						</constructor-arg>
  					    <constructor-arg value="$&#123;init&#58;table&#125;"/>
 					    <constructor-arg value="$&#123;init&#58;keyColumn&#125;"/>
					    <constructor-arg value="$&#123;init&#58;valueColumn&#125;"/>
				    </bean>
				 </constructor-arg>
			</bean>
		</property>
	</bean>
</beans>

[wpoitras]

Actually because of the recursive nature of my solution, you have to break it up into two contexts, with the bootstrap.xml being the parent to context.xml

bootstrap.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http&#58;//www.springframework.org/dtd/spring-beans.dtd">
<beans>
	<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
		<property name="location" value="db.properties"/>
	</bean>

	<bean id="myProps" class="org.apache.commons.configuration.ConfigurationConverter" factory-method="getProperties">
  		<constructor-arg>
			<bean class="org.apache.commons.configuration.DatabaseConfiguration">
		  		<constructor-arg>
					<bean id="ds1" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
				      <property name="driverClassName" value="$&#123;jdbc.driver&#125;"/>
				      <property name="url" value="$&#123;jdbc.url&#125;"/>
				      <property name="username" value="$&#123;jdbc.username&#125;"/>
				      <property name="password" value="$&#123;jdbc.password&#125;"/>
				    </bean> 	
		  		</constructor-arg>
			    <constructor-arg value="$&#123;config.table&#125;"/>
			    <constructor-arg value="$&#123;config.keyColumn&#125;"/>
			    <constructor-arg value="$&#123;config.valueColumn&#125;"/>
		    </bean>
		 </constructor-arg>
	</bean>
		
</beans>

context.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http&#58;//www.springframework.org/dtd/spring-beans.dtd">
<beans>
	<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
		<property name="properties" ref="myProps"/>
	</bean>

	<!-- Beans which use the db based properties goes here -->
</beans>

[adreghiciu]

In order to avoid the above situation of creating hierachical contexts the same can be archived as follow:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
  <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="propertiesArray">
      <list>
         <ref bean="myPropsFromFile"/>
         <ref bean="myPropsFromDb"/>
      </list>
    </property>
  </bean>

  <bean id="myPropsFromFile"
    class="org.springframework.beans.factory.config.PropertiesFactoryBean">
    <property name="location" value="db.properties"/>
  </bean>

  <bean id="myPropsFromDb" class="org.apache.commons.configuration.ConfigurationConverter" factory-method="getProperties">
    <constructor-arg>
      <bean class="org.apache.commons.configuration.DatabaseConfiguration">
        <constructor-arg>
          <bean id="ds1" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
            <property name="driverClassName" ref="prop.jdbc.driver"/>
            <property name="url" ref="prop.jdbc.url"/>
            <property name="username" ref="prop.jdbc.username"/>
            <property name="password" ref="prop.jdbc.password"/>
          </bean>
        </constructor-arg>
        <constructor-arg ref="prop.config.table"/>
        <constructor-arg ref="prop.config.keyColumn"/>
        <constructor-arg ref="prop.config.valueColumn"/>
      </bean>
    </constructor-arg>
  </bean>

  <bean id="prop.jdbc.driver"
    class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetObject" ref="myPropsFromFile" />
    <property name="targetMethod" value="getProperty" />
    <property name="arguments">
      <list>
        <value>jdbc.driver</value>
      </list>
    </property>
  </bean>

  <bean id="prop.jdbc.url"
    class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetObject" ref="myPropsFromFile" />
    <property name="targetMethod" value="getProperty" />
    <property name="arguments">
      <list>
        <value>jdbc.url</value>
      </list>
    </property>
  </bean>

  <bean id="prop.jdbc.username"
    class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetObject" ref="myPropsFromFile" />
    <property name="targetMethod" value="getProperty" />
    <property name="arguments">
      <list>
        <value>jdbc.username</value>
      </list>
    </property>
  </bean>

  <bean id="prop.jdbc.password"
    class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetObject" ref="myPropsFromFile" />
    <property name="targetMethod" value="getProperty" />
    <property name="arguments">
      <list>
        <value>jdbc.password</value>
      </list>
    </property>
  </bean>

  <bean id="prop.config.table"
    class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetObject" ref="myPropsFromFile" />
    <property name="targetMethod" value="getProperty" />
    <property name="arguments">
      <list>
        <value>config.table</value>
      </list>
    </property>
  </bean>

  <bean id="prop.config.keyColumn"
    class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetObject" ref="myPropsFromFile" />
    <property name="targetMethod" value="getProperty" />
    <property name="arguments">
      <list>
        <value>config.keyColumn</value>
      </list>
    </property>
  </bean>

  <bean id="prop.config.valueColumn"
    class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetObject" ref="myPropsFromFile" />
    <property name="targetMethod" value="getProperty" />
    <property name="arguments">
      <list>
        <value>config.valueColumn</value>
      </list>
    </property>
  </bean>

</beans>

This solves the problem by using the current proposition from spring but is quite verbose.
In order to make it shorter to configure you can use the facory beans from http://opensource.atlassian.com/proj...rowse/SPR-2335 andf then the configuration will change to:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
  <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="propertiesArray">
      <list>
         <ref bean="myPropsFromFile"/>
         <ref bean="myPropsFromDb"/>
      </list>
    </property>
  </bean>

  <bean id="myPropsFromFile"
    class="org.springframework.beans.factory.config.PropertiesFactoryBean">
    <property name="location" value="db.properties"/>
  </bean>

  <bean id="myPropsFromDb" class="org.apache.commons.configuration.ConfigurationConverter" factory-method="getProperties">
    <constructor-arg>
      <bean class="org.apache.commons.configuration.DatabaseConfiguration">
        <constructor-arg>
          <bean id="ds1" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
            <property name="driverClassName" ref="myPropsFromFile[jdbc.driver]"/>
            <property name="url" ref="myPropsFromFile[jdbc.url]"/>
            <property name="username" ref="myPropsFromFile[jdbc.username]"/>
            <property name="password" ref="myPropsFromFile[jdbc.password]"/>
          </bean>
        </constructor-arg>
        <constructor-arg ref="myPropsFromFile[config.table]"/>
        <constructor-arg ref="myPropsFromFile[config.keyColumn]"/>
        <constructor-arg ref="myPropsFromFile[config.valueColumn]"/>
      </bean>
    </constructor-arg>
  </bean>

  <bean name="myPropsFromFile[jdbc.driver]"
    class="org.springframework.beans.factory.config.PropertiesGetterFactoryBean"/>
    
  <bean name="myPropsFromFile[jdbc.url]"
    class="org.springframework.beans.factory.config.PropertiesGetterFactoryBean"/>    

  <bean name="myPropsFromFile[jdbc.username]"
    class="org.springframework.beans.factory.config.PropertiesGetterFactoryBean"/>

  <bean name="myPropsFromFile[jdbc.password]"
    class="org.springframework.beans.factory.config.PropertiesGetterFactoryBean"/>

  <bean name="myPropsFromFile[config.table]"
    class="org.springframework.beans.factory.config.PropertiesGetterFactoryBean"/>

  <bean name="myPropsFromFile[config.keyColumn]"
    class="org.springframework.beans.factory.config.PropertiesGetterFactoryBean"/>

  <bean name="myPropsFromFile[config.valueColumn]"
    class="org.springframework.beans.factory.config.PropertiesGetterFactoryBean"/>    
    
</beans>

Less verbose but no core Spring support.

[Chris Lee]

It's possible this is the referenced PropertyPlaceholderConfigurer

[adreghiciu]

Not the same use case. Please read http://opensource.atlassian.com/proj...5#action_19719

[Costin Leau]

Not sure if it helps, but Spring Modules provides integration with Commons Configuration.

[Dave Syer]

The Spring modules factory bean looks interesting, but I couldn't find any documentation (except the extremely minimal javadocs). Could you add a section / example to the main HTML docs?