Interface Converter<T>
Interface for converting configured values from String to any Java type.
Converters for the following types are provided by default:
boolean
andBoolean
, values fortrue
: (case insensitive) "true", "yes", "Y", "on", "1"int
andInteger
long
andLong
float
andFloat
, a dot '.' is used to separate the fractional digitsdouble
andDouble
, a dot '.' is used to separate the fractional digitsjava.lang.Class
based on the result ofClass.forName(java.lang.String)
Custom Converters will get picked up via the ServiceLoader
mechanism and and can be registered by
providing a file
META-INF/services/org.eclipse.microprofile.config.spi.Converter
which contains the fully qualified Converter
implementation class name as content.
A Converter can specify a javax.annotation.Priority
.
If no priority is explicitly assigned, the value of 100 is assumed.
If multiple Converters are registered for the same type, the one with the highest priority will be used. Highest number means highest priority.
Custom Converters can also be registered programmatically via `ConfigBuilder#withConverters(Converter... converters)` or
`ConfigBuilder#withConverter(Class type, int priority, Converter converter)`.
All Built In Converters have a javax.annotation.Priority
of 1
A Converter should handle null values returning either null or a valid Object of the specified type.
Array Converters
The implementation must support the Array converter for each built-in converters and custom converters. The delimiter for the config value is ",". The escape character is "\".e.g. myPets=dog,cat,dog\,cat
For the property injection, List and Set should be supported as well.
Usage:
String[] myPets = config.getValue("myPet", String[].class);
@Inject @ConfigProperty(name="myPets") private String[] myPets;
@Inject @ConfigProperty(name="myPets") private List<String> myPets;
@Inject @ConfigProperty(name="myPets") private Set<String> myPets;
myPets will be "dog", "cat", "dog,cat"
Implicit Converters
If no explicit Converter and no built-in Converter could be found for a certain type,
the Config
provides an Implicit Converter, if
- the target type
T
has apublic static T of(String)
method, or - the target type
T
has apublic static T valueOf(String)
method, or - the target type
T
has a public Constructor with a String parameter, or - the target type
T
has apublic static T parse(CharSequence)
method
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Method Summary
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Method Details
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convert
Configure the string value to a specified type- Parameters:
value
- the string representation of a property value.- Returns:
- the converted value or null
- Throws:
IllegalArgumentException
- if the value cannot be converted to the specified type.
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