spring PropertyPlaceholderConfigurer and context:property-placeholder

I have following bean declaration:

  <bean
     class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>WEB-INF/classes/config/properties/database.properties</value>
                <value>classpath:config/properties/database.properties</value>
            </list>
        </property>
        <property name="ignoreResourceNotFound" value="true"/>
    </bean>
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
    <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>

Now I want to change above PropertyPlaceholderConfigurer to following format:

<context:component-scan base-package="org.example.config"/>
<util:properties id="jdbcProperties" 
           location="classpath:config/properties/database.properties"/>

1. ignoreResourceNotFound will ignore the property while running. e.g: When testing application WEB-INF/.. path will ignore( since maven project and property file is under src/main/resources/..), while launching web application, other property will ignore path, I need to implement same with above format.
2. should be able to add multiple property file like database.properties, test.properties etc.
3. in Spring 3, can I use annotation instead of these xml files for DB loading, how can I do it? since I am using only one xml file(given above) to load db stuff.

I am using Spring 3 framework.

Solution 1:

<context:property-placeholder ... /> is the XML equivalent to the PropertyPlaceholderConfigurer. So, prefer that. The <util:properties/> simply factories a java.util.Properties instance that you can inject.

In Spring 3.1 (not 3.0...) you can do something like this:

@Configuration
@PropertySource("/foo/bar/services.properties")
public class ServiceConfiguration { 

    @Autowired Environment environment; 

    @Bean public javax.sql.DataSource dataSource( ){ 
        String user = this.environment.getProperty("ds.user");
        ...
    } 
}

In Spring 3.0, you can "access" properties defined using the PropertyPlaceHolderConfigurer mechanism using the SpEl annotations:

@Value("${ds.user}") private String user;

If you want to remove the XML all together, simply register the PropertyPlaceholderConfigurer manually using Java configuration. I prefer the 3.1 approach. But, if youre using the Spring 3.0 approach (since 3.1's not GA yet...), you can now define the above XML like this:

@Configuration 
public class MySpring3Configuration {     
        @Bean 
        public static PropertyPlaceholderConfigurer configurer() { 
             PropertyPlaceholderConfigurer ppc = ...
             ppc.setLocations(...);
             return ppc; 
        } 

        @Bean 
        public class DataSource dataSource(
                @Value("${ds.user}") String user, 
                @Value("${ds.pw}") String pw, 
                ...) { 
            DataSource ds = ...
            ds.setUser(user);
            ds.setPassword(pw);                        
            ...
            return ds;
        }
}

Note that the PPC is defined using a static bean definition method. This is required to make sure the bean is registered early, because the PPC is a BeanFactoryPostProcessor - it can influence the registration of the beans themselves in the context, so it necessarily has to be registered before everything else.

Solution 2:

First, you don't need to define both of those locations. Just use classpath:config/properties/database.properties. In a WAR, WEB-INF/classes is a classpath entry, so it will work just fine.

After that, I think what you mean is you want to use Spring's schema-based configuration to create a configurer. That would go like this:

<context:property-placeholder location="classpath:config/properties/database.properties"/>

Note that you don't need to "ignoreResourceNotFound" anymore. If you need to define the properties separately using util:properties:

<context:property-placeholder properties-ref="jdbcProperties" ignore-resource-not-found="true"/>

There's usually not any reason to define them separately, though.