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package javax.ws.rs.ext;

import java.lang.reflect.ReflectPermission;
import java.net.URL;

import javax.ws.rs.core.Application;
import javax.ws.rs.core.Link;
import javax.ws.rs.core.Response.ResponseBuilder;
import javax.ws.rs.core.UriBuilder;
import javax.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 = "javax.ws.rs.ext.RuntimeDelegate";
    private static final String JAXRS_DEFAULT_RUNTIME_DELEGATE = "org.glassfish.jersey.internal.RuntimeDelegateImpl";
    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/javax.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 javax.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 javax.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, JAXRS_DEFAULT_RUNTIME_DELEGATE, 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 javax.ws.rs.core.UriBuilder}. * * @return new {@code UriBuilder} instance. * @see javax.ws.rs.core.UriBuilder */ public abstract UriBuilder createUriBuilder(); /** * Create a new instance of a {@link javax.ws.rs.core.Response.ResponseBuilder}. * * @return new {@code ResponseBuilder} instance. * @see javax.ws.rs.core.Response.ResponseBuilder */ public abstract ResponseBuilder createResponseBuilder(); /** * Create a new instance of a {@link javax.ws.rs.core.Variant.VariantListBuilder}. * * @return new {@code VariantListBuilder} instance. * @see javax.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 javax.ws.rs.core.CacheControl}, {@link javax.ws.rs.core.Cookie}, * {@link javax.ws.rs.core.EntityTag}, {@link javax.ws.rs.core.Link}, * {@link javax.ws.rs.core.NewCookie}, {@link javax.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 javax.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 javax.ws.rs.core.Link.Builder}. * * @return new {@code Link.Builder} instance. * @see javax.ws.rs.core.Link.Builder */ public abstract Link.Builder createLinkBuilder(); }




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