Module jakarta.ws.rs
Package jakarta.ws.rs.ext

Interface ParamConverter<T>

Type Parameters:
T - the supported Java type convertible to/from a String format.
public interface ParamConverter<T>
Defines a contract for a delegate responsible for converting between a String form of a message parameter value and the corresponding custom Java type T. Conversion of message parameter values injected via @PathParam, @QueryParam, @MatrixParam, @FormParam, @CookieParam and @HeaderParam is supported. JAX-RS implementations MUST support the ParamConverter mechanism for all Java types. If a ParamConverter is available for a type, it MUST be preferred over all other conversion strategies mentioned in section 3.2 (i.e. single String argument constructor, static valueOf or fromString methods, etc.).

By default, when used for injection of parameter values, a selected ParamConverter instance MUST be used eagerly by a JAX-RS runtime to convert any default value in the resource or provider model, that is during the application deployment, before any value – default or otherwise – is actually required. This conversion strategy ensures that any errors in the default values are reported as early as possible. This default behavior may be overridden by annotating the ParamConverter implementation class with a @Lazy annotation. In such case any default value conversion delegated to the @Lazy-annotated converter will be deferred to a latest possible moment (i.e. until the injection of such default value is required).

NOTE: A service implementing this contract is not recognized as a registrable JAX-RS extension provider. Instead, a ParamConverterProvider instance responsible for providing ParamConverter instances has to be registered as one of the JAX-RS extension providers.

Since:
2.0
Author:
Marek Potociar

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static @interface 
    ParamConverter.Lazy
    Mandates that a conversion of any default value delegated to a parameter converter annotated with @Lazy annotation SHOULD occur only once the value is actually required (e.g.

  • Method Summary

    Modifier and Type
    Method
    Description
    T
    fromString(String value)
    Parse the supplied value and create an instance of T.
    String
    toString(T value)
    Convert the supplied value to a String.

  • Method Details

    • fromString

      T fromString(String value)
      Parse the supplied value and create an instance of T.
      Parameters:
      value - the string value.
      Returns:
      the newly created instance of T.
      Throws:
      IllegalArgumentException - if the supplied string cannot be parsed or is null.

    • toString

      String toString(T value)
      Convert the supplied value to a String.

      This method is reserved for future use. Proprietary JAX-RS extensions may leverage the method. Users should be aware that any such support for the method comes at the expense of producing non-portable code.

      Parameters:
      value - the value of type T.
      Returns:
      a String representation of the value.
      Throws:
      IllegalArgumentException - if the supplied object cannot be serialized or is null.