Modern web applications use a large number of static resources such as js files, css, fonts, images, etc.
Even if the internet connections are always more efficient, it’s always worth asking if it’s useful to use the resources caching, that’s to say to allow the browser to store static resources in its cache. In general it’s better to find the right compromise, since in reality resources can also change such as the application js files (very rarely those of the application stack).
Our web applications are based on Spring Boot and Spring MVC which by default do not allow the caching of resources.
To enable resource caching, you can intervene in the application config files. For example, if we want the cache to have a validity of one week,
you have to add the following line in the application.properties file:
spring.resources.cache-period=604800
If a particular resource handler is used, configure it for caching. For example, for resources loaded with the webjars protocol, we had to configure a resource handler for compatibility issues with Websphere. Even in this case just configure the cache period like this:
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
super.addResourceHandlers(registry);
registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/").
setCachePeriod(604800).resourceChain(true).addResolver(new WebJarsResourceResolver(new WasWebJarAssetLocator()));
}
To force the cache to refresh before expiry of the validity period (for example, if you release a new version of the application that requires changes substantial in the js files) two techniques can be used. On the client side, you can force the cache to be refreshed with the classic << Shift + F5 >> from the browser. On the server side you can use the file versioning technique, adding the version in the file name.
Giancarlo Parma 