Variables

Config files can contain variables that get resolved dynamically using the previously-described {@link oaj.svl.VarResolver} API.

##### Example:

#-------------------------- # My section #-------------------------- [MySection] # A system property locale = $S{java.locale, en_US} # An environment variable path = $E{PATH, unknown} # Another value in this config file anotherLocale = $C{MySection/locale} # Look for system property, or env var if that doesn't exist, or a default value if that doesn't exist. nested = $S{mySystemProperty,$E{MY_ENV_VAR,$C{MySection/anotherLocale}}} # A POJO with embedded variables aBean = {foo:'$S{foo}',baz:$C{MySection/anInt}}

Config config = Config.create().build(); Locale locale = config.getObject("MySection/locale", Locale.class); String path = config.getString("MySection/path"); int sameAsAnInt = config.getInt("MySection/sameAsAnInt"); ABean bean = config.getObject("MySection/aBean", ABean.class);

By default, Configs use the {@link oaj.svl.VarResolver#DEFAULT} variable resolver which provides support for the following variables and constructs:

- {@link oaj.svl.vars.SystemPropertiesVar} - $S{key[,default]}
- {@link oaj.svl.vars.EnvVariablesVar} - $E{key[,default]}
- {@link oaj.config.vars.ConfigVar} - $C{key[,default]}

The variable resolver is controlled via the following setting:

- {@link oaj.config.Config#CONFIG_varResolver}

Additionally, the following method can be used to retrieve a Config with a different variable resolver:

- {@link oaj.config.Config#resolving(VarResolverSession)}