Reading a List from properties file and load with spring annotation @Value

Question

I want to have a list of values in a .properties file, ie:

my.list.of.strings=ABC,CDE,EFG 

And to load it in my class directly, ie:

@Value("${my.list.of.strings}") private List<String> myList; 

As I understand, an alternative of doing this is to have it in the spring config file, and load it as a bean reference (correct me if I'm wrong), ie

<bean name="list">  <list>   <value>ABC</value>   <value>CDE</value>   <value>EFG</value>  </list> </bean> 

But is there any way of doing this? using a .properties file? ps: I would like to do this with out any custom code if possible.

Answer 1

Using Spring EL:

@Value("#{'${my.list.of.strings}'.split(',')}")  private List<String> myList; 

Assuming your properties file is loaded correctly with the following:

my.list.of.strings=ABC,CDE,EFG 

Answer 2

Since Spring 3.0, you can add a line like

<bean id="conversionService"      class="org.springframework.context.support.ConversionServiceFactoryBean" /> 

to your applicationContext.xml (or where you configure things). As Dmitry Chornyi points out in a comment, Java based configuration looks like:

@Bean public ConversionService conversionService() {     return new DefaultConversionService(); } 

This activates the new configuration service which supports converting String to Collection types. If you do not activate this configuration service, Spring falls back on its legacy property editors as configuration services, which do not support this kind of conversion.

Converting to collections of other types works, too:

@Value("${my.list.of.ints}") private List<Integer> myList 

will work with a line like

 my.list.of.ints= 1, 2, 3, 4 

No problems with whitespace there, the ConversionServiceFactoryBean takes care of it.

See http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#core-convert-Spring-config

In a Spring application, you typically configure a ConversionService instance per Spring container (or ApplicationContext). That ConversionService will be picked up by Spring and then used whenever a type conversion needs to be performed by the framework. [...] If no ConversionService is registered with Spring, the original PropertyEditor-based system is used.