How to inject a Map using the @Value Spring Annotation?

Question

How can I inject values into a Map from the properties file using the @Value annotation in Spring?

My Spring Java class is and I tried using the $, but got the following error message:

Could not autowire field: private java.util.Map Test.standard; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'com.test.standard' in string value "${com.test.standard}"

@ConfigurationProperty("com.hello.foo")
public class Test {

   @Value("${com.test.standard}")
   private Map<String,Pattern> standard = new LinkedHashMap<String,Pattern>

   private String enabled;

}

I have the following properties in a .properties file

com.test.standard.name1=Pattern1
com.test.standard.name2=Pattern2
com.test.standard.name3=Pattern3
com.hello.foo.enabled=true

Solution 1

I believe Spring Boot supports loading properties maps out of the box with @ConfigurationProperties annotation.

According that docs you can load properties:

my.servers[0]=dev.bar.com
my.servers[1]=foo.bar.com

into bean like this:

@ConfigurationProperties(prefix="my")
public class Config {

    private List<String> servers = new ArrayList<String>();

    public List<String> getServers() {
        return this.servers;
    }
}

I used @ConfigurationProperties feature before, but without loading into map. You need to use @EnableConfigurationProperties annotation to enable this feature.

Cool stuff about this feature is that you can validate your properties.

Solution 2

You can inject values into a Map from the properties file using the @Value annotation like this.

The property in the properties file.

propertyname={key1:'value1',key2:'value2',....}

In your code.

@Value("#{${propertyname}}")  private Map<String,String> propertyname;

Note the hashtag as part of the annotation.

Solution 3

You can inject .properties as a map in your class using @Resource annotation.

If you are working with XML based configuration, then add below bean in your spring configuration file:

 <bean id="myProperties" class="org.springframework.beans.factory.config.PropertiesFactoryBean">
      <property name="location" value="classpath:your.properties"/>
 </bean>

For, Annotation based:

@Bean(name = "myProperties")
public static PropertiesFactoryBean mapper() {
        PropertiesFactoryBean bean = new PropertiesFactoryBean();
        bean.setLocation(new ClassPathResource(
                "your.properties"));
        return bean;
}

Then you can pick them up in your application as a Map:

@Resource(name = "myProperties")
private Map<String, String> myProperties;

Solution 4

I had a simple code for Spring Cloud Config

like this:

In application.properties

spring.data.mongodb.db1=mongodb://[email protected]

spring.data.mongodb.db2=mongodb://[email protected]

read

@Bean(name = "mongoConfig")
@ConfigurationProperties(prefix = "spring.data.mongodb")
public Map<String, Map<String, String>> mongoConfig() {
    return new HashMap();
}

use

@Autowired
@Qualifier(value = "mongoConfig")
private Map<String, String> mongoConfig;

@Bean(name = "mongoTemplates")
public HashMap<String, MongoTemplate> mongoTemplateMap() throws UnknownHostException {
    HashMap<String, MongoTemplate> mongoTemplates = new HashMap<>();
    for (Map.Entry<String, String>> entry : mongoConfig.entrySet()) {
        String k = entry.getKey();
        String v = entry.getValue();
        MongoTemplate template = new MongoTemplate(new SimpleMongoDbFactory(new MongoClientURI(v)));
        mongoTemplates.put(k, template);
    }
    return mongoTemplates;
}

Solution 5

To get this working with YAML, do this:

property-name: '{
  key1: "value1",
  key2: "value2"
}'

View more solutions

Comments

[yathirigan]

yes but, my problem is.. The Test class has its own @ConfigurationProperties prefix. So i want to use a diff prefix for this member variable alone . how can i do that ?

[yathirigan]

We have used Spring Cloud Config server to provide the configurations, hence class path approach might not work. And we don't use XMLs

[luboskrnac]

hmm, I missed that. So I would create separate two beans with @ConfiguraitonProperties annotation and autowire them into test class.

[dustin.schultz]

values must be quotes, else I get a SpelEvaluationException

[petertc]

How to set default value if the property is absent to prevent exception occurred?

[partTimeNinja]

If you want to use strings with whitespaces ( e.g USB Camera 0xfd120000046d0819 ) as keys, use single quotes as for values.

[xenoterracide]

may have worked for the OP, but question didn't specify boot, and this problem doesn't work for general Spring, without boot.

[xenoterracide]

what if there's a : in the key?

[PeterK]

Also seems to do type conversions e.g.: @Value("#{${double.map}}") final Map<String, Double> doubleMap

[emanuel07]

How to set default value ?

[Mukul Anand]

the question is how to inject to a map using @Value annotation, but you are telling all sort of things rather than giving the answer to the question. Alternatives are okay but please stick to the answer as well

[Mukul Anand]

How to specify the same in a yml file

[joemat]

@MukulAnand in yaml it looks like this propertyname : > { key1:'value', key2:'value' } Sorry, I'm not able to format the linebreaks correct

[Mike D3ViD Tyson]

"Note the hashtag as part of the annotation..."

[David M. Karr]

Is it actually possible to do this? I'm trying to use SPeL in code to do the same thing, but it just says "No converter found capable of converting from type [java.lang.String] to type [java.util.Map<java.lang.String, java.lang.String>]".

[Andrey M. Stepanov]

pattern "propertyname: {key1:'value1',key2:'value2',....}" does not work when injecting map from .yaml : java.lang.IllegalArgumentException: Could not resolve placeholder

[rslj]

I think your definition for the bean mongoConfig is incorrect. The method should be defined like this. public Map<String, String> mongoConfig() { return new HashMap(); }

[Woland]

What if value has SpEL expression with '? :(

[g00glen00b]

Be aware, this isn't the same as using propertyname.key1=... and propertyname.key2=.... In stead, it uses a single property called propertyname. The equivalent in YAML is to treat it as a string as well and by wrapping it in quotes, such as: "{key1:'value1',key2:'value2',....}". For more infor, check this question.

[Agoston Horvath]

this is probably the most elegant way if you simply want to inject a map from application.yml

[PAA]

@MikeD3ViDTyson - Could you please guide me here: stackoverflow.com/questions/60899860/… ?

[PAA]

@Arpit - Could you please guide me here : stackoverflow.com/questions/60899860/…?

[Brunke]

Thank you for answering the actual question that was asked!!! The chosen answer may have been what the OP wanted to know. But, this answer actually answered the question THAT WAS ASKED!! Huge help!!! Thanks!

[Francois Marot]

you can set the default value like this for an empty map: @Value("#{${tomcat.oleaconfig:{:}}}")

[Artanis Zeratul]

how about Map<String, List<String>>? Is this possible?

[Simon Logic]

how to make proper fallback to empty map if property is not found? otherwise context won't be initialized.