Spring @Value Annotation: Property, SpEL, Map, Constructor, Setter, and Record Injection

Spring's @Value annotation can be used to inject values into Spring-managed bean properties, and it works on fields as well as constructor or method parameters.

Property injection examples : you can inject a literal string, a value from a properties file, a system property, or provide a default value when the property is missing. If a property exists both as a system property and in a file, the system property takes precedence. Comma‑separated values can be injected into an array, e.g., @Value("{listOfValues}") private String[] valuesArray;

Advanced SpEL examples : using Spring Expression Language you can retrieve system properties ( @Value("#{systemProperties['priority']}") private String spelValue; ), supply defaults with the Elvis operator ( @Value("#{systemProperties['unknown']?:'some default'}") private String spelSomeDefault; ), reference other beans ( @Value("#{someBean.someValue}") private Integer someBeanValue; ), split a comma‑separated list into a List ( @Value("#{'${listOfValues}'.split(',')}") private List valuesList; ), and inject maps defined in property files ( @Value("#{{valuesMap}}") private Map<String,Integer> valuesMap; ). You can access specific map keys ( @Value("#{{valuesMap}.key1}") private Integer valuesMapKey1; ), safely retrieve unknown keys with a default ( @Value("#{{valuesMap}['unknownKey']?:5}") private Integer unknownMapKeyWithDefaultValue; ), filter map entries ( @Value("#{{valuesMap}.?[value>'1']}") private Map<String,Integer> valuesMapFiltered; ), or inject all system properties as a map ( @Value("#{systemProperties}") private Map<String,String> systemPropertiesMap; ).

Constructor injection : @Autowired public PriorityProvider(@Value("${priority:normal}") String priority) { this.priority = priority; } injects a property directly into the constructor, with a default fallback.

Setter injection : private List<String> values = new ArrayList<>(); @Autowired public void setValues(@Value("#{'${listOfValues}'.split(',')}") List<String> values) { this.values.addAll(values); } demonstrates injecting a list via a setter method.

Note: method injection can also assign values to static fields.

Record injection : Since Java 14, records provide immutable data carriers, and Spring 6.0.6+ supports @Value on record components, e.g., @Component @PropertySource("classpath:values.properties") public record PriorityRecord(@Value("{priority:normal}") String priority) {} , injecting the value directly into the record's constructor.