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*
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*
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* and Distribution License("CDDL") (collectively, the "License"). You
* may not use this file except in compliance with the License. You can
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package org.glassfish.tyrus.core;
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.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.TreeSet;
import java.util.jar.Attributes;
import java.util.jar.Manifest;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.glassfish.tyrus.core.l10n.LocalizationMessages;
/**
* A simple service-provider lookup mechanism. A <i>service</i> is a
* well-known set of interfaces and (usually abstract) classes. A <i>service
* provider</i> 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.
* <p/>
* <p> 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 <i>service class</i> with data and code specific to
* the provider. This <i>provider class</i> 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.
* <p/>
* <p>The default service provider registration/lookup mechanism based
* on <tt>META-INF/services</tt> files is described below.
* For environments, where the basic mechanism is not suitable, clients
* can enforce a different approach by setting their custom <tt>ServiceIteratorProvider</tt>
* by calling <tt>setIteratorProvider</tt>. The call must be made prior to any lookup attempts.
* </p>
* <p> A service provider identifies itself by placing a provider-configuration
* file in the resource directory <tt>META-INF/services</tt>. 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 <tt>'#'</tt>
* (<tt>0x23</tt>); on each line all characters following the first comment
* character are ignored. The file must be encoded in UTF-8.
* <p/>
* <p> 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.
* <p/>
* <p> <b>Example:</b> Suppose we have a service class named
* <tt>java.io.spi.CharCodec</tt>. It has two abstract methods:
* <p/>
* <pre>
* public abstract CharEncoder getEncoder(String encodingName);
* public abstract CharDecoder getDecoder(String encodingName);
* </pre>
* <p/>
* Each method returns an appropriate object or <tt>null</tt> if it cannot
* translate the given encoding. Typical <tt>CharCodec</tt> providers will
* support more than one encoding.
* <p/>
* <p> If <tt>sun.io.StandardCodec</tt> is a provider of the <tt>CharCodec</tt>
* service then its jar file would contain the file
* <tt>META-INF/services/java.io.spi.CharCodec</tt>. This file would contain
* the single line:
* <p/>
* <pre>
* sun.io.StandardCodec # Standard codecs for the platform
* </pre>
* <p/>
* To locate an codec for a given encoding name, the internal I/O code would
* do something like this:
* <p/>
* <pre>
* CharEncoder getEncoder(String encodingName) {
* for( CharCodec cc : ServiceFinder.find(CharCodec.class) ) {
* CharEncoder ce = cc.getEncoder(encodingName);
* if (ce != null)
* return ce;
* }
* return null;
* }
* </pre>
* <p/>
* 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 <T> the type of the service instance.
* @author Mark Reinhold
* @author Jakub Podlesak
* @author Marek Potociar
*/
public final class ServiceFinder<T> implements Iterable<T> {
private static final Logger LOGGER = Logger.getLogger(ServiceFinder.class.getName());
private static final String MANIFEST = "META-INF/MANIFEST.MF";
private static final String MODULE_VERSION = "META-INF/jersey-module-version";
private static final String PREFIX = "META-INF/services/";
private static final String BUNDLE_VERSION_ATTRIBUTE = "Bundle-Version";
private static final String BUNDLE_SYMBOLIC_NAME_ATTRIBUTE = "Bundle-SymbolicName";
private static final String BUNDLE_VERSION = getBundleAttribute(BUNDLE_VERSION_ATTRIBUTE);
private static final String BUNDLE_SYMBOLIC_NAME = getBundleAttribute(BUNDLE_SYMBOLIC_NAME_ATTRIBUTE);
private static final String MODULE_VERSION_VALUE = getModuleVersion();
private final Class<T> serviceClass;
private final String serviceName;
private final ClassLoader classLoader;
private final boolean ignoreOnClassNotFound;
static {
final OsgiRegistry osgiRegistry = ReflectionHelper.getOsgiRegistryInstance();
if (osgiRegistry != null) {
LOGGER.log(Level.CONFIG, "Running in an OSGi environment");
osgiRegistry.hookUp();
} else {
LOGGER.log(Level.CONFIG, "Running in a non-OSGi environment");
}
}
private static String getBundleAttribute(String attributeName) {
try {
final String version = getManifest(ServiceFinder.class).
getMainAttributes().
getValue(attributeName);
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE, String.format("ServiceFinder %s: %s", attributeName, version));
}
return version;
} catch (Exception ex) {
LOGGER.log(Level.FINE, "Error loading META-INF/MANIFEST.MF associated with " + ServiceFinder.class.getName(), ex);
return null;
}
}
private static String getModuleVersion() {
try {
String resource = ServiceFinder.class.getName().replace(".", "/") + ".class";
URI uri = getResource(ServiceFinder.class.getClassLoader(), resource);
if (uri == null) {
LOGGER.log(Level.FINE, "Error getting {0} class as a resource", ServiceFinder.class.getName());
return null;
}
return getJerseyModuleVersion(getManifestURI(resource, uri));
} catch (Exception ioe) {
LOGGER.log(Level.FINE, "Error loading META-INF/jersey-module-version associated with " + ServiceFinder.class.getName(), ioe);
return null;
}
}
private static final Map<URI, Boolean> manifestURIs = new HashMap<URI, Boolean>();
private static Enumeration<URI> filterServiceURIsWithVersion(String serviceName, Enumeration<URI> serviceURIs) {
if (BUNDLE_VERSION == null || !serviceURIs.hasMoreElements()) {
return serviceURIs;
}
final List<URI> uris = Collections.list(serviceURIs);
final ListIterator<URI> li = uris.listIterator();
while (li.hasNext()) {
final URI uri = li.next();
try {
final URI manifestURI = getManifestURI(serviceName, uri);
synchronized (manifestURIs) {
Boolean keep = manifestURIs.get(manifestURI);
if (keep != null) {
if (!keep) {
if (LOGGER.isLoggable(Level.CONFIG)) {
LOGGER.log(Level.CONFIG, "Ignoring service URL: {0}", uri);
}
li.remove();
} else {
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE, "Including service URL: {0}", uri);
}
}
} else {
if (!compatibleManifest(manifestURI)) {
if (LOGGER.isLoggable(Level.CONFIG)) {
LOGGER.log(Level.CONFIG, "Ignoring service URL: {0}", uri);
}
li.remove();
manifestURIs.put(manifestURI, false);
} else {
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE, "Including service URL: {0}", uri);
}
manifestURIs.put(manifestURI, true);
}
}
}
} catch (IOException ex) {
LOGGER.log(Level.FINE, "Error loading META-INF/MANIFEST.MF associated with " + uri, ex);
}
}
return Collections.enumeration(uris);
}
private static boolean compatibleManifest(URI manifestURI) throws IOException {
final Attributes as = getManifest(manifestURI).getMainAttributes();
final String symbolicName = as.getValue(BUNDLE_SYMBOLIC_NAME_ATTRIBUTE);
final String version = as.getValue(BUNDLE_VERSION_ATTRIBUTE);
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE, "Checking META-INF/MANIFEST.MF URL: {0}\n "
+ BUNDLE_SYMBOLIC_NAME_ATTRIBUTE
+ ": {1}\n "
+ BUNDLE_VERSION_ATTRIBUTE
+ ": {2}",
new Object[]{manifestURI, symbolicName, version});
}
if (symbolicName != null
&& symbolicName.startsWith("com.sun.jersey")
&& !BUNDLE_VERSION.equals(version)) {
return false;
} else {
String moduleVersion = getJerseyModuleVersion(manifestURI);
if (moduleVersion != null
&& (!moduleVersion.equals(MODULE_VERSION_VALUE)
|| (symbolicName != null
&& (BUNDLE_SYMBOLIC_NAME.startsWith("com.sun.jersey") ^ symbolicName.startsWith("com.sun.jersey"))))) {
return false;
}
return true;
}
}
private static String getJerseyModuleVersion(URI manifestURI) {
BufferedReader reader = null;
try {
URL moduleVersionURL = new URL(manifestURI.toString().replace(MANIFEST, MODULE_VERSION));
reader = new BufferedReader(new InputStreamReader(moduleVersionURL.openStream(), "UTF-8"));
return reader.readLine();
} catch (IOException ioe) {
LOGGER.log(Level.FINE, "Error loading META-INF/jersey-module-version associated with " + ServiceFinder.class.getName(), ioe);
return null;
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException ex) {
Logger.getLogger(ServiceFinder.class.getName()).log(Level.FINE, "Error closing manifest located at URL: " + manifestURI, ex);
}
}
}
}
private static Manifest getManifest(Class c) throws IOException, URISyntaxException {
final String resource = c.getName().replace(".", "/") + ".class";
URI uri = getResource(c.getClassLoader(), resource);
if (uri == null) {
throw new IOException("Resource not found: " + resource);
}
return getManifest(resource, uri);
}
private static Manifest getManifest(String name, URI serviceURI) throws IOException {
return getManifest(getManifestURI(name, serviceURI));
}
private static URI getManifestURI(String name, URI serviceURI) throws IOException {
return URI.create(serviceURI.toString().replace(name, MANIFEST));
}
private static Manifest getManifest(URI uri) throws IOException {
final InputStream in = uri.toURL().openStream();
try {
return new Manifest(in);
} finally {
in.close();
}
}
private static URI getResource(ClassLoader loader, String name) throws IOException, URISyntaxException {
if (loader == null) {
return getResource(name);
} else {
final URL resource = loader.getResource(name);
if (resource != null) {
return resource.toURI();
} else {
return getResource(name);
}
}
}
private static URI getResource(String name) throws IOException, URISyntaxException {
if (ServiceFinder.class.getClassLoader() != null) {
final URL resource = ServiceFinder.class.getClassLoader().getResource(name);
if (resource != null) {
return resource.toURI();
}
return null;
} else {
final URL systemResource = ClassLoader.getSystemResource(name);
if (systemResource != null) {
return systemResource.toURI();
}
return null;
}
}
private static Enumeration<URI> getResources(ClassLoader loader, String name) throws IOException {
if (loader == null) {
return getResources(name);
} else {
final Enumeration<URL> resources = loader.getResources(name);
if ((resources != null) && resources.hasMoreElements()) {
return transformEnumeration(resources);
} else {
return getResources(name);
}
}
}
private static Enumeration<URI> transformEnumeration(final Enumeration<URL> original) {
return new Enumeration<URI>() {
@Override
public boolean hasMoreElements() {
return original.hasMoreElements();
}
@Override
public URI nextElement() {
try {
return original.nextElement().toURI();
} catch (URISyntaxException e) {
return null;
}
}
};
}
private static Enumeration<URI> getResources(String name) throws IOException {
if (ServiceFinder.class.getClassLoader() != null) {
return transformEnumeration(ServiceFinder.class.getClassLoader().getResources(name));
} else {
return transformEnumeration(ClassLoader.getSystemResources(name));
}
}
/**
* Locates and incrementally instantiates the available providers of a
* given service using the given class loader.
* <p/>
* <p> This method transforms the name of the given service class into a
* provider-configuration filename as described above and then uses the
* <tt>getResources</tt> 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.
* <p/>
* <p> 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. <p>
*
* @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 <tt>null</tt> if the system
* class loader (or, failing that the bootstrap class loader) is to
* be used
* @param <T> the type of the service instance.
* @return the service finder
* @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)
*/
public static <T> ServiceFinder<T> find(Class<T> 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.
* <p/>
* <p> This method transforms the name of the given service class into a
* provider-configuration filename as described above and then uses the
* <tt>getResources</tt> 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.
* <p/>
* <p> 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. <p>
*
* @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 <tt>null</tt> 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.
* @param <T> the type of the service instance.
* @return the service finder
* @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)
*/
public static <T> ServiceFinder<T> find(Class<T> service,
ClassLoader loader,
boolean ignoreOnClassNotFound) throws ServiceConfigurationError {
return new ServiceFinder<T>(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
* <p/>
* <pre>
* ClassLoader cl = Thread.currentThread().getContextClassLoader();
* return Service.providers(service, cl, false);
* </pre>
*
* @param service The service's abstract service class
* @param <T> the type of the service instance.
* @return the service finder
* @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)
*/
public static <T> ServiceFinder<T> find(Class<T> 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
* <p/>
* <pre>
* ClassLoader cl = Thread.currentThread().getContextClassLoader();
* boolean ingore = ...
* return Service.providers(service, cl, ignore);
* </pre>
*
* @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.
* @param <T> the type of the service instance.
* @return the service finder
* @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)
*/
public static <T> ServiceFinder<T> find(Class<T> 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
* @return the service finder
* @throws ServiceConfigurationError If a service file violates the specified format
* or names a provider class that cannot be found and instantiated
*/
public static ServiceFinder<?> find(String serviceName) throws ServiceConfigurationError {
return new ServiceFinder<Object>(Object.class, serviceName, Thread.currentThread().getContextClassLoader(), false);
}
/**
* Register the service iterator provider to iterate on provider instances
* or classes.
* <p/>
* The default implementation registered, {@link DefaultServiceIteratorProvider},
* looks up provider classes in META-INF/service files.
* <p/>
* 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<T> service,
ClassLoader loader,
boolean ignoreOnClassNotFound) {
this(service, service.getName(), loader, ignoreOnClassNotFound);
}
private ServiceFinder(
Class<T> 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 <tt>Iterator</tt> that yields provider objects for the given
* service, in some arbitrary order. The iterator will throw a
* <tt>ServiceConfigurationError</tt> if a provider-configuration
* file violates the specified format or if a provider class cannot
* be found and instantiated.
*/
@Override
public Iterator<T> iterator() {
return ServiceIteratorProvider.getInstance().createIterator(serviceClass, serviceName, classLoader, ignoreOnClassNotFound);
}
/**
* Returns discovered classes incrementally.
*
* @return An <tt>Iterator</tt> that yields provider classes for the given
* service, in some arbitrary order. The iterator will throw a
* <tt>ServiceConfigurationError</tt> if a provider-configuration
* file violates the specified format or if a provider class cannot
* be found.
*/
private Iterator<Class<T>> 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<T> result = new ArrayList<T>();
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<T>[] toClassArray() throws ServiceConfigurationError {
List<Class<T>> result = new ArrayList<Class<T>>();
Iterator<Class<T>> i = classIterator();
while (i.hasNext()) {
result.add(i.next());
}
return result.toArray((Class<T>[]) 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, URI 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, URI u, BufferedReader r, int lc,
List<String> names, Set<String> 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, LocalizationMessages.ILLEGAL_CONFIG_SYNTAX());
}
int cp = ln.codePointAt(0);
if (!Character.isJavaIdentifierStart(cp)) {
fail(serviceName, u, lc, LocalizationMessages.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, LocalizationMessages.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 <tt>Iterator</tt>.
* @return A (possibly empty) <tt>Iterator</tt> 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<String> parse(String serviceName, URI u, Set<String> returned)
throws ServiceConfigurationError {
InputStream in = null;
BufferedReader r = null;
ArrayList<String> names = new ArrayList<String>();
try {
URLConnection uConn = u.toURL().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) {
// continue
}
} 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<T> {
final Class<T> service;
final String serviceName;
final ClassLoader loader;
final boolean ignoreOnClassNotFound;
Enumeration<URI> configs = null;
Iterator<String> pending = null;
final Set<String> returned = new TreeSet<String>();
String nextName = null;
private AbstractLazyIterator(
Class<T> 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 = filterServiceURIsWithVersion(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,
LocalizationMessages.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,
LocalizationMessages.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,
LocalizationMessages.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<T> extends AbstractLazyIterator<T>
implements Iterator<Class<T>> {
private LazyClassIterator(
Class<T> service,
String serviceName,
ClassLoader loader,
boolean ignoreOnClassNotFound) {
super(service, serviceName, loader, ignoreOnClassNotFound);
}
@Override
public Class<T> next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
String cn = nextName;
nextName = null;
try {
return ReflectionHelper.classForNameWithException(cn, loader);
} catch (ClassNotFoundException ex) {
fail(serviceName,
LocalizationMessages.PROVIDER_NOT_FOUND(cn, service));
} catch (NoClassDefFoundError ex) {
fail(serviceName,
LocalizationMessages.DEPENDENT_CLASS_OF_PROVIDER_NOT_FOUND(
ex.getLocalizedMessage(), cn, service));
} catch (ClassFormatError ex) {
fail(serviceName,
LocalizationMessages.DEPENDENT_CLASS_OF_PROVIDER_FORMAT_ERROR(
ex.getLocalizedMessage(), cn, service));
} catch (Exception x) {
fail(serviceName,
LocalizationMessages.PROVIDER_CLASS_COULD_NOT_BE_LOADED(cn, service, x.getLocalizedMessage()),
x);
}
return null; /* This cannot happen */
}
}
private static final class LazyObjectIterator<T> extends AbstractLazyIterator<T> implements Iterator<T> {
private T t;
private LazyObjectIterator(
Class<T> 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,
LocalizationMessages.PROVIDER_NOT_FOUND(nextName, service));
}
nextName = null;
} else {
fail(serviceName,
LocalizationMessages.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,
LocalizationMessages.DEPENDENT_CLASS_OF_PROVIDER_NOT_FOUND(
ex.getLocalizedMessage(), nextName, service));
}
nextName = null;
} else {
fail(serviceName,
LocalizationMessages.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,
LocalizationMessages.DEPENDENT_CLASS_OF_PROVIDER_FORMAT_ERROR(
ex.getLocalizedMessage(), nextName, service));
}
nextName = null;
} else {
fail(serviceName,
LocalizationMessages.DEPENDENT_CLASS_OF_PROVIDER_FORMAT_ERROR(ex.getLocalizedMessage(), nextName, service),
ex);
}
} catch (Exception ex) {
fail(serviceName,
LocalizationMessages.PROVIDER_COULD_NOT_BE_CREATED(nextName, service, ex.getLocalizedMessage()),
ex);
}
}
return true;
}
@Override
public T next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
String cn = nextName;
nextName = null;
return t;
}
}
/**
* Supports iteration of provider instances or classes.
* <p/>
* The default implementation looks up provider classes from META-INF/services
* files, see {@link DefaultServiceIteratorProvider}.
* This implementation may be overridden by invoking
*/
public static abstract class ServiceIteratorProvider {
private static volatile ServiceIteratorProvider sip;
private static final Object sipLock = new Object();
private static ServiceIteratorProvider getInstance() {
// TODO: check the following is a good practice: Double-check idiom for lazy initialization of fields.
ServiceIteratorProvider result = sip;
if (result == null) { // First check (no locking)
synchronized (sipLock) {
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 (sipLock) {
ServiceIteratorProvider.sip = sip;
}
}
/**
* Iterate over provider instances of a service.
*
* @param <T> the type of the 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 <T> Iterator<T> createIterator(Class<T> service,
String serviceName, ClassLoader loader, boolean ignoreOnClassNotFound);
/**
* Iterate over provider classes of a service.
*
* @param <T> the type of the 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 <T> Iterator<Class<T>> createClassIterator(Class<T> service,
String serviceName, ClassLoader loader, boolean ignoreOnClassNotFound);
}
/**
* The default service iterator provider that looks up provider classes in
* META-INF/services files.
* <p/>
* This class may utilized if a {@link ServiceIteratorProvider} needs to
* reuse the default implementation.
*/
public static final class DefaultServiceIteratorProvider extends ServiceIteratorProvider {
@Override
public <T> Iterator<T> createIterator(Class<T> service, String serviceName,
ClassLoader loader, boolean ignoreOnClassNotFound) {
return new LazyObjectIterator<T>(service, serviceName, loader, ignoreOnClassNotFound);
}
@Override
public <T> Iterator<Class<T>> createClassIterator(Class<T> service, String serviceName,
ClassLoader loader, boolean ignoreOnClassNotFound) {
return new LazyClassIterator<T>(service, serviceName, loader, ignoreOnClassNotFound);
}
}
}