How to Inject a Comma-Separated List from a Properties File into a Spring Bean Using @Value?

Reading a List from Properties File Using Spring Annotation @Value

Problem:

You want to load a list of values from a properties file and directly inject it into your class using the Spring @Value annotation. The values are represented as a comma-separated list.

Answer:

1. Using Spring Expression Language (EL)

To load a list of values using Spring EL, annotate a field with @Value and specify the EL expression to extract the values:

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

This expression uses the split() function to separate the values in the properties file into a list.

2. Using Spring Configuration Bean

Alternatively, you can define a bean in your Spring configuration file and inject it using @Value:

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

Then, in your class:

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

Note: Ensure that your properties file is correctly loaded in your Spring application context.

Custom Code Option:

If you want to make this work without custom code, you can create a custom PropertySource that reads the list from the properties file. However, this option is not currently supported out-of-the-box.

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