Does Spring MessageSource Support Multiple Class Path?

user_204950 0
Viewed 28015

I am designing a plugin system for our web based application using Spring framework. Plugins are jars on classpath. So I am able to get sources such as jsp, see below

ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
Resource[] pages = resolver.getResources("classpath*:jsp/*jsp");

So far so good. But I have a problem with the messageSource. It seems to me that ReloadableResourceBundleMessageSource#setBasename does NOT support multiple class path via the "classpath*:" If I use just "classpath:", I get the messageSource just only from one plugin.

Does anyone have an idea how to register messageSources from all plugins? Does exist such an implementation of MessageSource?

classpath plugins spring java
7 Answers

overriding ReloadableResourceBundleMessageSource::calculateFilenamesForLocale may be better. Then, ReloadableResourceBundleMessageSource::getProperties can get PropertiesHolder from cachedProperties

user_53086810

You can take advantage of Java configuration and hierarchical message sources to build a quite simple plugin system. In each pluggable jar drop a class like this:

@Configuration
public class MyPluginConfig {
    @Bean
    @Qualifier("external")
    public HierarchicalMessageSource mypluginMessageSource() {
        ReloadableResourceBundleMessageSource messageSource = new ReloadableResourceBundleMessageSource();
        messageSource.setBasenames("classpath:my-plugin-messages");
        return messageSource;
    }
}

and the corresponding my-plugin-messages.properties files.

In the main application Java config class put something like this:

@Configuration
public class MainConfig {
    @Autowired(required = false)
    @Qualifier("external")
    private List<HierarchicalMessageSource> externalMessageSources = Collections.emptyList();

    @Bean
    public MessageSource messageSource() {
        ReloadableResourceBundleMessageSource rootMessageSource = new ReloadableResourceBundleMessageSource();
        rootMessageSource.setBasenames("classpath:messages");

        if (externalMessageSources.isEmpty()) {
            // No external message sources found, just main message source will be used
            return rootMessageSource;
        }
        else {
            // Wiring detected external message sources, putting main message source as "last resort"
            int count = externalMessageSources.size();

            for (int i = 0; i < count; i++) {
                HierarchicalMessageSource current = externalMessageSources.get(i);
                current.setParentMessageSource( i == count - 1 ? rootMessageSource : externalMessageSources.get(i + 1) );
            }
            return externalMessageSources.get(0);
        }
    }
}

If the order of plugins is relevant, just put @Order annotations in each pluggable message source bean.

user_9743550

As @Jia Feng said an alternative solution overriding ReloadableResourceBundleMessageSource::calculateFilenamesForLocale.

It works on spring 5.x

public class WildcardReloadableResourceBundleMessageSource extends ReloadableResourceBundleMessageSource {

    private static final String PROPERTIES_SUFFIX = ".properties";
    private PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();   
    
    @Override
    protected List<String> calculateFilenamesForLocale(String basename, Locale locale) {
        List<String> filenames = super.calculateFilenamesForLocale(basename, locale);
        List<String> add = new ArrayList<>();
        for (String filename : filenames) {
            try {
                Resource[] resources = resolver.getResources(filename + PROPERTIES_SUFFIX);
                for (Resource resource : resources) {
                    String sourcePath = resource.getURI().toString().replace(PROPERTIES_SUFFIX, "");
                    add.add(sourcePath);
                }
            } catch (IOException ignored) {
            }
        }
        filenames.addAll(add);
        return filenames;
    }
    
}
user_97366510
Related