jakarta.ws.rs.ext.RuntimeDelegate Maven / Gradle / Ivy
/*
* Copyright (c) 2010, 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.reflect.ReflectPermission;
import java.net.URL;
import jakarta.ws.rs.core.Application;
import jakarta.ws.rs.core.Link;
import jakarta.ws.rs.core.Response.ResponseBuilder;
import jakarta.ws.rs.core.UriBuilder;
import jakarta.ws.rs.core.Variant.VariantListBuilder;
/**
* Implementations of JAX-RS provide a concrete subclass of RuntimeDelegate and various JAX-RS API methods defer to
* methods of RuntimeDelegate for their functionality. Regular users of JAX-RS are not expected to use this class
* directly and overriding an implementation of this class with a user supplied subclass may cause unexpected behavior.
*
* @author Paul Sandoz
* @author Marc Hadley
* @since 1.0
*/
public abstract class RuntimeDelegate {
/**
* Name of the property identifying the {@link RuntimeDelegate} implementation to be returned from
* {@link RuntimeDelegate#getInstance()}.
*/
public static final String JAXRS_RUNTIME_DELEGATE_PROPERTY = "jakarta.ws.rs.ext.RuntimeDelegate";
private static final Object RD_LOCK = new Object();
private static ReflectPermission suppressAccessChecksPermission = new ReflectPermission("suppressAccessChecks");
private static volatile RuntimeDelegate cachedDelegate;
/**
* Allows custom implementations to extend the {@code RuntimeDelegate} class.
*/
protected RuntimeDelegate() {
}
/**
* Obtain a {@code RuntimeDelegate} instance. If an instance had not already been created and set via
* {@link #setInstance(RuntimeDelegate)}, the first invocation will create an instance which will then be cached for
* future use.
*
*
* The algorithm used to locate the RuntimeDelegate subclass to use consists of the following steps:
*
*
* - If a resource with the name of {@code META-INF/services/jakarta.ws.rs.ext.RuntimeDelegate} exists, then its first
* line, if present, is used as the UTF-8 encoded name of the implementation class.
* - If the $java.home/lib/jaxrs.properties file exists and it is readable by the
* {@code java.util.Properties.load(InputStream)} method and it contains an entry whose key is
* {@code jakarta.ws.rs.ext.RuntimeDelegate}, then the value of that entry is used as the name of the implementation
* class.
* - If a system property with the name {@code jakarta.ws.rs.ext.RuntimeDelegate} is defined, then its value is used as
* the name of the implementation class.
* - Finally, a default implementation class name is used.
*
*
* @return an instance of {@code RuntimeDelegate}.
*/
public static RuntimeDelegate getInstance() {
// Double-check idiom for lazy initialization of fields.
// Local variable is used to limit the number of more expensive accesses to a volatile field.
RuntimeDelegate result = cachedDelegate;
if (result == null) { // First check (no locking)
synchronized (RD_LOCK) {
result = cachedDelegate;
if (result == null) { // Second check (with locking)
cachedDelegate = result = findDelegate();
}
}
}
return result;
}
/**
* Obtain a {@code RuntimeDelegate} instance using the method described in {@link #getInstance}.
*
* @return an instance of {@code RuntimeDelegate}.
*/
private static RuntimeDelegate findDelegate() {
try {
Object delegate = FactoryFinder.find(JAXRS_RUNTIME_DELEGATE_PROPERTY, RuntimeDelegate.class);
if (!(delegate instanceof RuntimeDelegate)) {
Class pClass = RuntimeDelegate.class;
String classnameAsResource = pClass.getName().replace('.', '/') + ".class";
ClassLoader loader = pClass.getClassLoader();
if (loader == null) {
loader = ClassLoader.getSystemClassLoader();
}
URL targetTypeURL = loader.getResource(classnameAsResource);
throw new LinkageError("ClassCastException: attempting to cast"
+ delegate.getClass().getClassLoader().getResource(classnameAsResource)
+ " to " + targetTypeURL);
}
return (RuntimeDelegate) delegate;
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
/**
* Set the runtime delegate that will be used by JAX-RS classes. If this method is not called prior to
* {@link #getInstance} then an implementation will be sought as described in {@link #getInstance}.
*
* @param rd the runtime delegate instance
* @throws SecurityException if there is a security manager and the permission ReflectPermission("suppressAccessChecks")
* has not been granted.
*/
public static void setInstance(final RuntimeDelegate rd) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkPermission(suppressAccessChecksPermission);
}
synchronized (RD_LOCK) {
RuntimeDelegate.cachedDelegate = rd;
}
}
/**
* Create a new instance of a {@link jakarta.ws.rs.core.UriBuilder}.
*
* @return new {@code UriBuilder} instance.
* @see jakarta.ws.rs.core.UriBuilder
*/
public abstract UriBuilder createUriBuilder();
/**
* Create a new instance of a {@link jakarta.ws.rs.core.Response.ResponseBuilder}.
*
* @return new {@code ResponseBuilder} instance.
* @see jakarta.ws.rs.core.Response.ResponseBuilder
*/
public abstract ResponseBuilder createResponseBuilder();
/**
* Create a new instance of a {@link jakarta.ws.rs.core.Variant.VariantListBuilder}.
*
* @return new {@code VariantListBuilder} instance.
* @see jakarta.ws.rs.core.Variant.VariantListBuilder
*/
public abstract VariantListBuilder createVariantListBuilder();
/**
* Create a configured instance of the supplied endpoint type. How the returned endpoint instance is published is
* dependent on the type of endpoint.
*
* @param endpoint type.
* @param application the application configuration.
* @param endpointType the type of endpoint instance to be created.
* @return a configured instance of the requested type.
* @throws java.lang.IllegalArgumentException if application is null or the requested endpoint type is not supported.
* @throws java.lang.UnsupportedOperationException if the implementation supports no endpoint types.
*/
public abstract T createEndpoint(Application application, Class endpointType)
throws IllegalArgumentException, UnsupportedOperationException;
/**
* Obtain an instance of a {@link HeaderDelegate} for the supplied class. An implementation is required to support the
* following values for type: {@link jakarta.ws.rs.core.CacheControl}, {@link jakarta.ws.rs.core.Cookie},
* {@link jakarta.ws.rs.core.EntityTag}, {@link jakarta.ws.rs.core.Link}, {@link jakarta.ws.rs.core.NewCookie},
* {@link jakarta.ws.rs.core.MediaType} and {@code java.util.Date}.
*
* @param header type.
* @param type the class of the header.
* @return an instance of {@code HeaderDelegate} for the supplied type.
* @throws java.lang.IllegalArgumentException if type is {@code null}.
* @see jakarta.ws.rs.ext.RuntimeDelegate.HeaderDelegate
*/
public abstract HeaderDelegate createHeaderDelegate(Class type)
throws IllegalArgumentException;
/**
* Defines the contract for a delegate that is responsible for converting between the String form of a HTTP header and
* the corresponding JAX-RS type {@code T}.
*
* @param a JAX-RS type that corresponds to the value of a HTTP header.
*/
public static interface HeaderDelegate {
/**
* 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.
*
* @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);
}
/**
* Create a new instance of a {@link jakarta.ws.rs.core.Link.Builder}.
*
* @return new {@code Link.Builder} instance.
* @see jakarta.ws.rs.core.Link.Builder
*/
public abstract Link.Builder createLinkBuilder();
}
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