3.7 Extensions and Advanced Use
3.7.1 Using extensions
3.7.2 Advanced use
Why perform
- parameter validation,
- checks for presence of mandatory settings,
- generation of parameter documentation yourself? mConfig has a built-in facility for this and more.
You describe all the entries your configuration can have, and mConfig takes care of the checking.
3.7.3 Data types
3.7.3.1 Config scheme formats
3.7.3.1.1 Internal format 0: single ConfigSchemeEntry
{
"key":"mandatory key / configuration entry name",
"TYPE":"mandatory type",
"DEFAULT":"optional default value, as string",
"DESCRIPTION":"optional description, for the documentation",
"DESCRIPTION":{"en":"English description", "de":"Deutsche Beschreibung"},
"PATTERN":"optional validation pattern",
"SCOPES":[ "optional", "scopes", "this", "is", "valid", "in"],
"FLAGS":["flags"],
"SECRET":false,
"HIDDEN":false
}
Multi-language descriptions are supported by providing a map of language codes to description texts. When requested via getDescription(Locale), the library will first check this map, then fall back to standard ResourceBundle lookup (using .config/messages.properties), and finally fall back to the single string description if provided.
PLAN: For FLAGS, in the future we may chose an alternative form - each being a pair with string key and boolean value.
3.7.3.1.2 Internal format 1: ConfigSchemes, in an array. internal use only!
[
SCHEME_ENTRIES,
GO_HERE,
DEFINED_AS_IN_FORMAT_1
]
3.7.3.1.3 Format 2: full single ConfigScheme
{
"name":"mandatory name the Configuration is identified by",
"entries":[ ENTRIES_AS_DEFINED_IN_FORMAT_2 ],
}
3.7.3.1.4 Format 3: multiple full ConfigSchemes
[
FULL_CONFIG_SCHEME_AS_DEFINED_IN_FORMAT_3
]
stateDiagram-v2
direction LR
[*] --> UNDECIDED
UNDECIDED --> ARRAY : on [
UNDECIDED --> SCHEME: on {
SCHEME --> SCHEME_ENDED : on }
SCHEME --> ENTRY_KEY: on string
ENTRY --> SCHEME: on next value
3.7.4 configure priorities
3.7.4.1 File Type Priority
You can control the resolution priority between different file types (e.g., JSON, YAML) using the FILE_TYPE_PRIORITIES feature. This re-orders the search list within each scope.
3.7.4.2 Storage Type Priority
You can control the resolution priority between different storage types (e.g., Files vs. Registry) using the STORAGE_TYPE_PRIORITIES feature. This re-orders the search list within each scope.
ConfigFactoryBuilder builder = ConfigFactoryBuilder.create("company", "app")
.setFeature(ConfigFeature.STORAGE_TYPE_PRIORITIES, List.of("files", "registry", "registryjni", "JAR"));
try (ConfigFactory factory = builder.build())
{
// ...
}
RAM, secrets, files, registry, registryjni, JAR.
Additional directories provided via features like ADDITIONAL_USER_DIRECTORIES are typically prepended to the search list for their scope. This makes them the preferred location for creating new configuration files, while still allowing default files in standard locations to provide values (unless the same key is defined in the additional directory).