The ResourceLoader interface is meant to be implemented by objects that can return (i.e. load) Resource instances.

public interface ResourceLoader {
    Resource getResource(String location);
}

All application contexts implement the ResourceLoader interface, and therefore all application contexts may be used to obtain Resource instances.

When you call getResource() on a specific application context, and the location path specified doesn't have a specific prefix, you will get back a Resource type that is appropriate to that particular application context. For example, assume the following snippet of code was executed against a ClassPathXmlApplicationContext instance:

Resource template = ctx.getResource("some/resource/path/myTemplate.txt);

What would be returned would be a ClassPathResource; if the same method was executed against a FileSystemXmlApplicationContext instance, you'd get back a FileSystemResource. For a WebApplicationContext, you'd get back a ServletContextResource, and so on.

As such, you can load resources in a fashion appropriate to the particular application context.

On the other hand, you may also force ClassPathResource to be used, regardless of the application context type, by specifying the special classpath: prefix:

Resource template = ctx.getResource("classpath:some/resource/path/myTemplate.txt);

Similarly, one can force a UrlResource to be used by specifying any of the standard java.net.URL prefixes:

Resource template = ctx.getResource("file:/some/resource/path/myTemplate.txt);

Resource template = ctx.getResource("http://myhost.com/resource/path/myTemplate.txt);

The following table summarizes the strategy for converting Strings to Resources: