com.sun.jersey.spi.service.ServiceFinder Maven / Gradle / Ivy
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package com.sun.jersey.spi.service;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Array;
import java.lang.reflect.ReflectPermission;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.TreeSet;
import java.util.logging.Level;
import java.util.logging.Logger;
import com.sun.jersey.core.osgi.OsgiRegistry;
import com.sun.jersey.core.reflection.ReflectionHelper;
import com.sun.jersey.impl.SpiMessages;
/**
* A simple service-provider lookup mechanism. A service is a
* well-known set of interfaces and (usually abstract) classes. A service
* provider is a specific implementation of a service. The classes in a
* provider typically implement the interfaces and subclass the classes defined
* in the service itself. Service providers may be installed in an
* implementation of the Java platform in the form of extensions, that is, jar
* files placed into any of the usual extension directories. Providers may
* also be made available by adding them to the applet or application class
* path or by some other platform-specific means.
*
* In this lookup mechanism a service is represented by an interface or an
* abstract class. (A concrete class may be used, but this is not
* recommended.) A provider of a given service contains one or more concrete
* classes that extend this service class with data and code specific to
* the provider. This provider class will typically not be the entire
* provider itself but rather a proxy that contains enough information to
* decide whether the provider is able to satisfy a particular request together
* with code that can create the actual provider on demand. The details of
* provider classes tend to be highly service-specific; no single class or
* interface could possibly unify them, so no such class has been defined. The
* only requirement enforced here is that provider classes must have a
* zero-argument constructor so that they may be instantiated during lookup.
*
* The default service provider registration/lookup mechanism based
* on META-INF/services files is described below.
* For environments, where the basic mechanism is not suitable, clients
* can enforce a different approach by setting their custom ServiceIteratorProvider
* by calling setIteratorProvider. The call must be made prior to any lookup attempts.
*
* A service provider identifies itself by placing a provider-configuration
* file in the resource directory META-INF/services. The file's name
* should consist of the fully-qualified name of the abstract service class.
* The file should contain a list of fully-qualified concrete provider-class
* names, one per line. Space and tab characters surrounding each name, as
* well as blank lines, are ignored. The comment character is '#'
* (0x23); on each line all characters following the first comment
* character are ignored. The file must be encoded in UTF-8.
*
* If a particular concrete provider class is named in more than one
* configuration file, or is named in the same configuration file more than
* once, then the duplicates will be ignored. The configuration file naming a
* particular provider need not be in the same jar file or other distribution
* unit as the provider itself. The provider must be accessible from the same
* class loader that was initially queried to locate the configuration file;
* note that this is not necessarily the class loader that found the file.
*
* Example: Suppose we have a service class named
* java.io.spi.CharCodec. It has two abstract methods:
*
*
* public abstract CharEncoder getEncoder(String encodingName);
* public abstract CharDecoder getDecoder(String encodingName);
*
*
* Each method returns an appropriate object or null if it cannot
* translate the given encoding. Typical CharCodec providers will
* support more than one encoding.
*
* If sun.io.StandardCodec is a provider of the CharCodec
* service then its jar file would contain the file
* META-INF/services/java.io.spi.CharCodec. This file would contain
* the single line:
*
*
* sun.io.StandardCodec # Standard codecs for the platform
*
*
* To locate an codec for a given encoding name, the internal I/O code would
* do something like this:
*
*
* CharEncoder getEncoder(String encodingName) {
* for( CharCodec cc : ServiceFinder.find(CharCodec.class) ) {
* CharEncoder ce = cc.getEncoder(encodingName);
* if (ce != null)
* return ce;
* }
* return null;
* }
*
*
* The provider-lookup mechanism always executes in the security context of the
* caller. Trusted system code should typically invoke the methods in this
* class from within a privileged security context.
*
* @param the type of the service instance.
* @author Mark Reinhold (mark.reinhold at oracle.com)
* @author Jakub Podlesak (jakub.podlesak at oracle.com)
* @author Michal Gajdos (michal.gajdos at oracle.com)
*/
public final class ServiceFinder implements Iterable {
private static final Logger LOGGER = Logger.getLogger(ServiceFinder.class.getName());
private static final String MODULE_VERSION = "META-INF/jersey-module-version";
private static final String PREFIX = "META-INF/services/";
private static final String MODULE_VERSION_VALUE = getModuleVersion();
private static final Set MODULES_BLACKLIST;
private final Class serviceClass;
private final String serviceName;
private final ClassLoader classLoader;
private final boolean ignoreOnClassNotFound;
static {
MODULES_BLACKLIST = new HashSet() {{
// Jersey
add("jersey-client");
add("jersey-core");
add("jersey-gf-server");
add("jersey-gf-servlet");
add("jersey-gf-statsproviders");
add("jersey-grizzly");
add("jersey-json");
add("jersey-moxy");
add("jersey-multipart");
add("jersey-server");
add("jersey-servlet");
add("jersey-statsproviders");
// GF
add("glassfish-embedded");
}};
final OsgiRegistry osgiRegistry = ReflectionHelper.getOsgiRegistryInstance();
if (osgiRegistry != null) {
LOGGER.log(Level.CONFIG, "Running in an OSGi environment");
} else {
LOGGER.log(Level.CONFIG, "Running in a non-OSGi environment");
}
}
private static String getModuleVersion() {
try {
String resource = ServiceFinder.class.getName().replace(".", "/") + ".class";
URL url = getResource(ServiceFinder.class.getClassLoader(), resource);
if (url == null) {
LOGGER.log(Level.FINE, "Error getting " + ServiceFinder.class.getName() + " class as a resource");
return null;
}
return getJerseyModuleVersion(ServiceFinder.class.getName(), url);
} catch(IOException ioe) {
LOGGER.log(Level.FINE, "Error loading META-INF/jersey-module-version associated with " + ServiceFinder.class.getName(), ioe);
return null;
}
}
private static Enumeration filterServiceURLsWithVersion(String serviceName, Enumeration serviceUrls) {
if (MODULE_VERSION_VALUE == null || !serviceUrls.hasMoreElements()) {
return serviceUrls;
}
final List urls = Collections.list(serviceUrls);
final ListIterator li = urls.listIterator();
while (li.hasNext()) {
final URL url = li.next();
if (isServiceInBlacklistedModule(url)) {
String jerseyModuleVersion = getJerseyModuleVersion(serviceName, url);
if (jerseyModuleVersion != null) {
if (!MODULE_VERSION_VALUE.equals(jerseyModuleVersion)) {
li.remove();
}
}
}
}
return Collections.enumeration(urls);
}
private static boolean isServiceInBlacklistedModule(final URL serviceUrl) {
final String service = serviceUrl.toString();
for (final String module : MODULES_BLACKLIST) {
if (service.contains(module)) {
return true;
}
}
return false;
}
private static String getJerseyModuleVersion(final String serviceName, final URL serviceUrl) {
try {
final String url = serviceUrl.toString();
final String resource = url.endsWith("class") ? serviceName.replace(".", "/") + ".class" : serviceName;
final URL moduleVersionURL = new URL(url.replace(resource, MODULE_VERSION));
return new BufferedReader(new InputStreamReader(moduleVersionURL.openStream())).readLine();
} catch (IOException ioe) {
LOGGER.log(Level.FINE, "Error loading META-INF/jersey-module-version associated with " + ServiceFinder.class.getName());
return null;
}
}
private static URL getResource(ClassLoader loader, String name) throws IOException {
if (loader == null)
return getResource(name);
else {
final URL resource = loader.getResource(name);
if (resource != null) {
return resource;
} else {
return getResource(name);
}
}
}
private static URL getResource(String name) throws IOException {
if (ServiceFinder.class.getClassLoader() != null)
return ServiceFinder.class.getClassLoader().getResource(name);
else
return ClassLoader.getSystemResource(name);
}
private static Enumeration getResources(ClassLoader loader, String name) throws IOException {
if (loader == null) {
return getResources(name);
} else {
final Enumeration resources = loader.getResources(name);
if ((resources != null) && resources.hasMoreElements()) {
return resources;
} else {
return getResources(name);
}
}
}
private static Enumeration getResources(String name) throws IOException {
if (ServiceFinder.class.getClassLoader() != null)
return ServiceFinder.class.getClassLoader().getResources(name);
else
return ClassLoader.getSystemResources(name);
}
/**
* Locates and incrementally instantiates the available providers of a
* given service using the given class loader.
*
* This method transforms the name of the given service class into a
* provider-configuration filename as described above and then uses the
* getResources method of the given class loader to find all
* available files with that name. These files are then read and parsed to
* produce a list of provider-class names. The iterator that is returned
* uses the given class loader to lookup and then instantiate each element
* of the list.
*
* Because it is possible for extensions to be installed into a running
* Java virtual machine, this method may return different results each time
* it is invoked.
* @param service The service's abstract service class
* @param loader The class loader to be used to load provider-configuration files
* and instantiate provider classes, or null if the system
* class loader (or, failing that the bootstrap class loader) is to
* be used
* @throws ServiceConfigurationError If a provider-configuration file violates the specified format
* or names a provider class that cannot be found and instantiated
* @see #find(Class)
* @param the type of the service instance.
* @return the service finder
*/
public static ServiceFinder find(Class service, ClassLoader loader)
throws ServiceConfigurationError {
return find(service,
loader,
false);
}
/**
* Locates and incrementally instantiates the available providers of a
* given service using the given class loader.
*
* This method transforms the name of the given service class into a
* provider-configuration filename as described above and then uses the
* getResources method of the given class loader to find all
* available files with that name. These files are then read and parsed to
* produce a list of provider-class names. The iterator that is returned
* uses the given class loader to lookup and then instantiate each element
* of the list.
*
* Because it is possible for extensions to be installed into a running
* Java virtual machine, this method may return different results each time
* it is invoked.
* @param service The service's abstract service class
* @param loader The class loader to be used to load provider-configuration files
* and instantiate provider classes, or null if the system
* class loader (or, failing that the bootstrap class loader) is to
* be used
* @param ignoreOnClassNotFound If a provider cannot be loaded by the class loader
* then move on to the next available provider.
* @throws ServiceConfigurationError If a provider-configuration file violates the specified format
* or names a provider class that cannot be found and instantiated
* @see #find(Class)
* @param the type of the service instance.
* @return the service finder
*/
public static ServiceFinder find(Class service,
ClassLoader loader,
boolean ignoreOnClassNotFound) throws ServiceConfigurationError {
return new ServiceFinder(service,
loader,
ignoreOnClassNotFound);
}
/**
* Locates and incrementally instantiates the available providers of a
* given service using the context class loader. This convenience method
* is equivalent to
*
*
* ClassLoader cl = Thread.currentThread().getContextClassLoader();
* return Service.providers(service, cl, false);
*
* @param service The service's abstract service class
* @throws ServiceConfigurationError If a provider-configuration file violates the specified format
* or names a provider class that cannot be found and instantiated
* @see #find(Class, ClassLoader)
* @param the type of the service instance.
* @return the service finder
*/
public static ServiceFinder find(Class service)
throws ServiceConfigurationError {
return find(service,
Thread.currentThread().getContextClassLoader(),
false);
}
/**
* Locates and incrementally instantiates the available providers of a
* given service using the context class loader. This convenience method
* is equivalent to
*
*
* ClassLoader cl = Thread.currentThread().getContextClassLoader();
* boolean ingore = ...
* return Service.providers(service, cl, ignore);
*
* @param service The service's abstract service class
* @param ignoreOnClassNotFound If a provider cannot be loaded by the class loader
* then move on to the next available provider.
* @throws ServiceConfigurationError If a provider-configuration file violates the specified format
* or names a provider class that cannot be found and instantiated
* @see #find(Class, ClassLoader)
* @param the type of the service instance.
* @return the service finder
*/
public static ServiceFinder find(Class service,
boolean ignoreOnClassNotFound) throws ServiceConfigurationError {
return find(service,
Thread.currentThread().getContextClassLoader(),
ignoreOnClassNotFound);
}
/**
* Locates and incrementally instantiates the available classes of a given
* service file using the context class loader.
*
* @param serviceName the service name correspond to a file in
* META-INF/services that contains a list of fully qualified class
* names
* @throws ServiceConfigurationError If a service file violates the specified format
* or names a provider class that cannot be found and instantiated
* @return the service finder
*/
public static ServiceFinder find(String serviceName) throws ServiceConfigurationError {
return new ServiceFinder(Object.class, serviceName, Thread.currentThread().getContextClassLoader(), false);
}
/**
* Register the service iterator provider to iterate on provider instances
* or classes.
*
* The default implementation registered, {@link DefaultServiceIteratorProvider},
* looks up provider classes in META-INF/service files.
*
* This method must be called prior to any attempts to obtain provider
* instances or classes.
*
* @param sip the service iterator provider.
* @throws SecurityException if the provider cannot be registered.
*/
public static void setIteratorProvider(ServiceIteratorProvider sip) throws SecurityException {
ServiceIteratorProvider.setInstance(sip);
}
private ServiceFinder(
Class service,
ClassLoader loader,
boolean ignoreOnClassNotFound) {
this(service, service.getName(), loader, ignoreOnClassNotFound);
}
private ServiceFinder(
Class service,
String serviceName,
ClassLoader loader,
boolean ignoreOnClassNotFound) {
this.serviceClass = service;
this.serviceName = serviceName;
this.classLoader = loader;
this.ignoreOnClassNotFound = ignoreOnClassNotFound;
}
/**
* Returns discovered objects incrementally.
*
* @return An Iterator that yields provider objects for the given
* service, in some arbitrary order. The iterator will throw a
* ServiceConfigurationError if a provider-configuration
* file violates the specified format or if a provider class cannot
* be found and instantiated.
*/
public Iterator iterator() {
return ServiceIteratorProvider.getInstance().createIterator(serviceClass, serviceName, classLoader, ignoreOnClassNotFound);
}
/**
* Returns discovered classes incrementally.
*
* @return An Iterator that yields provider classes for the given
* service, in some arbitrary order. The iterator will throw a
* ServiceConfigurationError if a provider-configuration
* file violates the specified format or if a provider class cannot
* be found.
*/
private Iterator> classIterator() {
return ServiceIteratorProvider.getInstance().createClassIterator(serviceClass, serviceName, classLoader, ignoreOnClassNotFound);
}
/**
* Returns discovered objects all at once.
*
* @return
* can be empty but never null.
*
* @throws ServiceConfigurationError If a provider-configuration file violates the specified format
* or names a provider class that cannot be found and instantiated
*/
@SuppressWarnings("unchecked")
public T[] toArray() throws ServiceConfigurationError {
List result = new ArrayList();
for (T t : this) {
result.add(t);
}
return result.toArray((T[])Array.newInstance(serviceClass,result.size()));
}
/**
* Returns discovered classes all at once.
*
* @return
* can be empty but never null.
*
* @throws ServiceConfigurationError If a provider-configuration file violates the specified format
* or names a provider class that cannot be found
*/
@SuppressWarnings("unchecked")
public Class[] toClassArray() throws ServiceConfigurationError {
List> result = new ArrayList>();
Iterator> i = classIterator();
while (i.hasNext())
result.add(i.next());
return result.toArray((Class[])Array.newInstance(Class.class,result.size()));
}
private static void fail(String serviceName, String msg, Throwable cause)
throws ServiceConfigurationError {
ServiceConfigurationError sce
= new ServiceConfigurationError(serviceName + ": " + msg);
sce.initCause(cause);
throw sce;
}
private static void fail(String serviceName, String msg)
throws ServiceConfigurationError {
throw new ServiceConfigurationError(serviceName + ": " + msg);
}
private static void fail(String serviceName, URL u, int line, String msg)
throws ServiceConfigurationError {
fail(serviceName, u + ":" + line + ": " + msg);
}
/**
* Parse a single line from the given configuration file, adding the name
* on the line to both the names list and the returned set iff the name is
* not already a member of the returned set.
*/
private static int parseLine(String serviceName, URL u, BufferedReader r, int lc,
List names, Set returned)
throws IOException, ServiceConfigurationError {
String ln = r.readLine();
if (ln == null) {
return -1;
}
int ci = ln.indexOf('#');
if (ci >= 0) ln = ln.substring(0, ci);
ln = ln.trim();
int n = ln.length();
if (n != 0) {
if ((ln.indexOf(' ') >= 0) || (ln.indexOf('\t') >= 0))
fail(serviceName, u, lc, SpiMessages.ILLEGAL_CONFIG_SYNTAX());
int cp = ln.codePointAt(0);
if (!Character.isJavaIdentifierStart(cp))
fail(serviceName, u, lc, SpiMessages.ILLEGAL_PROVIDER_CLASS_NAME(ln));
for (int i = Character.charCount(cp); i < n; i += Character.charCount(cp)) {
cp = ln.codePointAt(i);
if (!Character.isJavaIdentifierPart(cp) && (cp != '.'))
fail(serviceName, u, lc, SpiMessages.ILLEGAL_PROVIDER_CLASS_NAME(ln));
}
if (!returned.contains(ln)) {
names.add(ln);
returned.add(ln);
}
}
return lc + 1;
}
/**
* Parse the content of the given URL as a provider-configuration file.
*
* @param serviceName The service class for which providers are being sought;
* used to construct error detail strings
* @param u The URL naming the configuration file to be parsed
* @param returned A Set containing the names of provider classes that have already
* been returned. This set will be updated to contain the names
* that will be yielded from the returned Iterator.
* @return A (possibly empty) Iterator that will yield the
* provider-class names in the given configuration file that are
* not yet members of the returned set
* @throws ServiceConfigurationError If an I/O error occurs while reading from the given URL, or
* if a configuration-file format error is detected
*/
@SuppressWarnings({"StatementWithEmptyBody"})
private static Iterator parse(String serviceName, URL u, Set returned)
throws ServiceConfigurationError {
InputStream in = null;
BufferedReader r = null;
ArrayList names = new ArrayList();
try {
URLConnection uConn = u.openConnection();
uConn.setUseCaches(false);
in = uConn.getInputStream();
r = new BufferedReader(new InputStreamReader(in, "utf-8"));
int lc = 1;
while ((lc = parseLine(serviceName, u, r, lc, names, returned)) >= 0) ;
} catch (IOException x) {
fail(serviceName, ": " + x);
} finally {
try {
if (r != null) r.close();
if (in != null) in.close();
} catch (IOException y) {
fail(serviceName, ": " + y);
}
}
return names.iterator();
}
private static class AbstractLazyIterator {
final Class service;
final String serviceName;
final ClassLoader loader;
final boolean ignoreOnClassNotFound;
Enumeration configs = null;
Iterator pending = null;
Set returned = new TreeSet();
String nextName = null;
private AbstractLazyIterator(
Class service,
String serviceName,
ClassLoader loader,
boolean ignoreOnClassNotFound) {
this.service = service;
this.serviceName = serviceName;
this.loader = loader;
this.ignoreOnClassNotFound = ignoreOnClassNotFound;
}
protected final void setConfigs() {
if (configs == null) {
try {
final String fullName = PREFIX + serviceName;
configs = filterServiceURLsWithVersion(fullName, getResources(loader, fullName));
} catch (IOException x) {
fail(serviceName, ": " + x);
}
}
}
public boolean hasNext() throws ServiceConfigurationError {
if (nextName != null) {
return true;
}
setConfigs();
while (nextName == null) {
while ((pending == null) || !pending.hasNext()) {
if (!configs.hasMoreElements()) {
return false;
}
pending = parse(serviceName, configs.nextElement(), returned);
}
nextName = pending.next();
if (ignoreOnClassNotFound) {
try {
ReflectionHelper.classForNameWithException(nextName, loader);
} catch (ClassNotFoundException ex) {
// Provider implementation not found
if(LOGGER.isLoggable(Level.CONFIG)) {
LOGGER.log(Level.CONFIG,
SpiMessages.PROVIDER_NOT_FOUND(nextName, service));
}
nextName = null;
} catch (NoClassDefFoundError ex) {
// Dependent class of provider not found
if(LOGGER.isLoggable(Level.CONFIG)) {
// This assumes that ex.getLocalizedMessage() returns
// the name of a dependent class that is not found
LOGGER.log(Level.CONFIG ,
SpiMessages.DEPENDENT_CLASS_OF_PROVIDER_NOT_FOUND(
ex.getLocalizedMessage(), nextName, service));
}
nextName = null;
} catch(ClassFormatError ex) {
// Dependent class of provider not found
if(LOGGER.isLoggable(Level.CONFIG)) {
LOGGER.log(Level.CONFIG ,
SpiMessages.DEPENDENT_CLASS_OF_PROVIDER_FORMAT_ERROR(
ex.getLocalizedMessage(), nextName, service));
}
nextName = null;
}
}
}
return true;
}
public void remove() {
throw new UnsupportedOperationException();
}
}
private static final class LazyClassIterator extends AbstractLazyIterator
implements Iterator> {
private LazyClassIterator(
Class service,
String serviceName,
ClassLoader loader,
boolean ignoreOnClassNotFound) {
super(service, serviceName, loader, ignoreOnClassNotFound);
}
@SuppressWarnings("unchecked")
public Class next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
String cn = nextName;
nextName = null;
try {
return (Class)ReflectionHelper.classForNameWithException(cn, loader);
} catch (ClassNotFoundException ex) {
fail(serviceName,
SpiMessages.PROVIDER_NOT_FOUND(cn, service));
} catch (NoClassDefFoundError ex) {
fail(serviceName,
SpiMessages.DEPENDENT_CLASS_OF_PROVIDER_NOT_FOUND(
ex.getLocalizedMessage(), cn, service));
} catch (ClassFormatError ex) {
fail(serviceName,
SpiMessages.DEPENDENT_CLASS_OF_PROVIDER_FORMAT_ERROR(
ex.getLocalizedMessage(), cn, service));
} catch (Exception x) {
fail(serviceName,
SpiMessages.PROVIDER_CLASS_COULD_NOT_BE_LOADED(cn, service, x.getLocalizedMessage()),
x);
}
return null; /* This cannot happen */
}
}
private static final class LazyObjectIterator extends AbstractLazyIterator
implements Iterator {
private T t;
private LazyObjectIterator(
Class service,
String serviceName,
ClassLoader loader,
boolean ignoreOnClassNotFound) {
super(service, serviceName, loader, ignoreOnClassNotFound);
}
@Override
public boolean hasNext() throws ServiceConfigurationError {
if (nextName != null) {
return true;
}
setConfigs();
while (nextName == null) {
while ((pending == null) || !pending.hasNext()) {
if (!configs.hasMoreElements()) {
return false;
}
pending = parse(serviceName, configs.nextElement(), returned);
}
nextName = pending.next();
try {
t = service.cast(ReflectionHelper.classForNameWithException(nextName, loader).newInstance());
} catch (ClassNotFoundException ex) {
if (ignoreOnClassNotFound) {
// Provider implementation not found
if(LOGGER.isLoggable(Level.WARNING)) {
LOGGER.log(Level.WARNING,
SpiMessages.PROVIDER_NOT_FOUND(nextName, service));
}
nextName = null;
} else
fail(serviceName,
SpiMessages.PROVIDER_NOT_FOUND(nextName, service));
} catch (NoClassDefFoundError ex) {
// Dependent class of provider not found
if (ignoreOnClassNotFound) {
if(LOGGER.isLoggable(Level.CONFIG)) {
// This assumes that ex.getLocalizedMessage() returns
// the name of a dependent class that is not found
LOGGER.log(Level.CONFIG ,
SpiMessages.DEPENDENT_CLASS_OF_PROVIDER_NOT_FOUND(
ex.getLocalizedMessage(), nextName, service));
}
nextName = null;
} else
fail(serviceName,
SpiMessages.DEPENDENT_CLASS_OF_PROVIDER_NOT_FOUND(ex.getLocalizedMessage(), nextName, service),
ex);
} catch (ClassFormatError ex) {
// Dependent class of provider not found
if (ignoreOnClassNotFound) {
if(LOGGER.isLoggable(Level.CONFIG)) {
LOGGER.log(Level.CONFIG ,
SpiMessages.DEPENDENT_CLASS_OF_PROVIDER_FORMAT_ERROR(
ex.getLocalizedMessage(), nextName, service));
}
nextName = null;
} else
fail(serviceName,
SpiMessages.DEPENDENT_CLASS_OF_PROVIDER_FORMAT_ERROR(ex.getLocalizedMessage(), nextName, service),
ex);
} catch(Exception ex) {
fail(serviceName,
SpiMessages.PROVIDER_COULD_NOT_BE_CREATED(nextName, service, ex.getLocalizedMessage()),
ex);
}
}
return true;
}
public T next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
String cn = nextName;
nextName = null;
return t;
}
}
/**
* Supports iteration of provider instances or classes.
*
* The default implementation looks up provider classes from META-INF/services
* files, see {@link DefaultServiceIteratorProvider}.
* This implementation may be overridden by invoking
* {@link ServiceFinder#setIteratorProvider(com.sun.jersey.spi.service.ServiceFinder.ServiceIteratorProvider)}.
*
* @param the type of service.
*/
public static abstract class ServiceIteratorProvider {
private static volatile ServiceIteratorProvider sip;
private static ServiceIteratorProvider getInstance() {
// Double-check idiom for lazy initialization of fields.
ServiceIteratorProvider result = sip;
if (result == null) { // First check (no locking)
synchronized (ServiceIteratorProvider.class) {
result = sip;
if (result == null) { // Second check (with locking)
sip = result = new DefaultServiceIteratorProvider();
}
}
}
return result;
}
private static void setInstance(ServiceIteratorProvider sip) throws SecurityException {
SecurityManager security = System.getSecurityManager();
if (security != null) {
ReflectPermission rp = new ReflectPermission("suppressAccessChecks");
security.checkPermission(rp);
}
synchronized (ServiceIteratorProvider.class) {
ServiceIteratorProvider.sip = sip;
}
}
/**
* Iterate over provider instances of a service.
*
* @param service the service class.
* @param serviceName the service name.
* @param loader the class loader to utilize when loading provider
* classes.
* @param ignoreOnClassNotFound, if true ignore an instance if the
* corresponding provider class if cannot be found,
* otherwise throw a {@link ClassNotFoundException}.
* @return the provider instance iterator.
*/
public abstract Iterator createIterator(Class service,
String serviceName, ClassLoader loader, boolean ignoreOnClassNotFound);
/**
* Iterate over provider classes of a service.
*
* @param service the service class.
* @param serviceName the service name.
* @param loader the class loader to utilize when loading provider
* classes.
* @param ignoreOnClassNotFound, if true ignore the provider class if
* cannot be found,
* otherwise throw a {@link ClassNotFoundException}.
* @return the provider class iterator.
*/
public abstract Iterator> createClassIterator(Class service,
String serviceName, ClassLoader loader, boolean ignoreOnClassNotFound);
}
/**
* The default service iterator provider that looks up provider classes in
* META-INF/services files.
*
* This class may utilized if a {@link ServiceIteratorProvider} needs to
* reuse the default implementation.
*
* @param the type of service.
*/
public static final class DefaultServiceIteratorProvider extends ServiceIteratorProvider {
@Override
public Iterator createIterator(Class service, String serviceName,
ClassLoader loader, boolean ignoreOnClassNotFound) {
return new LazyObjectIterator(service, serviceName, loader, ignoreOnClassNotFound);
}
@Override
public Iterator> createClassIterator(Class service, String serviceName,
ClassLoader loader, boolean ignoreOnClassNotFound) {
return new LazyClassIterator(service, serviceName, loader, ignoreOnClassNotFound);
}
}
}