Binding #ConfigurationProperties to builder used to create bean - spring

Question

I'm creating multiple Caffeine caches like:
#Bean
public Cache<String, Customer> customerCache() {
return Caffeine.newBuilder()
.maximumSize(10_000)
// other config settings
.build(..);
}
Now I would like to use something like a #ConfigurationProperties(prefix = "cache.customer") to set the builder config options.
Where a application property cache.customer.maximum-size: 1000 exists.
Is there something smart I can do to map the #ConfigurationProperties to the Caffeine builder?

Answer 1

For future readers here is code I used to use Spring Boot's #ConfigurationProperties to configure a Caffeine Cache:
import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;
/**
* Base class for configuration of a Caffeine {#link Cache}
*/
public class CaffeineCacheProperties {
private Integer maximumSize;
// TODO: Add additional properties + getters and setters.
public Integer getMaximumSize() {
return maximumSize;
}
public void setMaximumSize(final Integer maximumSize) {
this.maximumSize = maximumSize;
}
public Caffeine initializeCacheBuilder() {
Caffeine cacheBuilder = Caffeine.newBuilder();
if (maximumSize != null) {
cacheBuilder.maximumSize(maximumSize);
}
// TODO: Configure additional properties.
return cacheBuilder;
}
}
.
import com.github.benmanes.caffeine.cache.Cache;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* The cache {#link Configuration} class.
*/
#Configuration
public class CacheConfig {
#Bean
#ConfigurationProperties("cache.customer")
public CaffeineCacheProperties customerCacheProperties() {
return new CacheProperties();
}
#Bean
public Cache<String, Customer> customerCache() {
return customerCacheProperties().initializeCacheBuilder().build();
}
// TODO: Add other caches.
}
And then add a application property like:
cache.customer.maximum-size: 1000

Answer 2

You can do something similar to what the boot team has done with DataSourceProperties:
https://github.com/spring-projects/spring-boot/blob/master/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceProperties.java
You bind your properties into a property class and then use a method on that properties class to create your builder.
Here is a different example where we are binding both the properties and a data source to the same root:
#Bean
#ConfigurationProperties("datasource.task")
public DataSourceProperties taskDataSourceProperties() {
return new DataSourceProperties();
}
#Bean(name = {"taskDataSource"}, destroyMethod="")
#ConfigurationProperties("datasource.task")
#ConditionalOnMissingBean(name="taskDataSource")
public DataSource taskDataSource() {
return taskDataSourceProperties().initializeDataSourceBuilder().build();
}

Answer 3

You can use #ConfigurationProperties(prefix = "cache.customer") on top of your CacheConfig class (A configurations class) where you can easily bind the application properties to your Cache class by using #EnableConfigurationProperties(CacheConfig.class).
So now you can auto wire the CacheConfig class to your Cache class and save it as a private attribute in your cache class. And then you can use that configurations through builder like
#Bean
public Cache<String, Customer> customerCache() {
return Caffeine.newBuilder()
.maximumSize(cacheConfig.getMaximumSize())
// other config settings
.build(..);
}