Binding @ConfigurationProperties to builder used to create bean

问题

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?

回答1:

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();
    }

回答2:

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

回答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(..);
}

来源：https://stackoverflow.com/questions/51983637/binding-configurationproperties-to-builder-used-to-create-bean

标签

Spring

spring-boot

caching

caffeine