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/*
* Copyright (c) 2012, 2019 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package jakarta.ws.rs.ext;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import jakarta.ws.rs.DefaultValue;
/**
* Defines a contract for a delegate responsible for converting between a {@code String} form of a message parameter
* value and the corresponding custom Java type {@code T}.
*
* Conversion of message parameter values injected via {@link jakarta.ws.rs.PathParam @PathParam},
* {@link jakarta.ws.rs.QueryParam @QueryParam}, {@link jakarta.ws.rs.MatrixParam @MatrixParam},
* {@link jakarta.ws.rs.FormParam @FormParam}, {@link jakarta.ws.rs.CookieParam @CookieParam} and
* {@link jakarta.ws.rs.HeaderParam @HeaderParam} is supported.
* JAX-RS implementations MUST support the {@code ParamConverter} mechanism for all Java types. If a
* {@code ParamConverter} is available for a type, it MUST be preferred over all other conversion strategies mentioned
* in section 3.2 (i.e. single {@code String} argument constructor, static {@code valueOf} or {@code fromString}
* methods, etc.).
*
* By default, when used for injection of parameter values, a selected {@code ParamConverter} instance MUST be used
* eagerly by a JAX-RS runtime to convert any {@link DefaultValue 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 {@code ParamConverter} implementation class with a {@link Lazy
* @Lazy} annotation. In such case any default value conversion delegated to the {@code @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
* {@link ParamConverterProvider} instance responsible for providing {@code ParamConverter} instances has to be
* registered as one of the JAX-RS extension providers.
*
*
* @param the supported Java type convertible to/from a {@code String} format.
* @author Marek Potociar
* @since 2.0
*/
public interface ParamConverter {
/**
* Mandates that a conversion of any {@link DefaultValue default value} delegated to a {@link ParamConverter parameter
* converter} annotated with {@code @Lazy} annotation SHOULD occur only once the value is actually required (e.g. to be
* injected for the first time).
*
* @since 2.0
*/
@Target({ ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
public static @interface Lazy {
}
/**
* Parse the supplied value and create an instance of {@code T}.
*
* @param value the string value.
* @return the newly created instance of {@code T}.
*
* @throws IllegalArgumentException if the supplied string cannot be parsed or is {@code null}.
*/
public T fromString(String 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.
*
*
* @param value the value of type {@code T}.
* @return a String representation of the value.
*
* @throws IllegalArgumentException if the supplied object cannot be serialized or is {@code null}.
*/
public String toString(T value);
}