src/javax/xml/datatype/FactoryFinder.java
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rev 406 : 8005954: JAXP Plugability Layer should use java.util.ServiceLoader
Summary: This fix replaces manual processing of files under META-INF/services in JAXP factories by calls to java.util.ServiceLoader.
Reviewed-by: alanb, joehw, mchung
@@ -1,7 +1,7 @@
/*
- * Copyright (c) 2004, 2006, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
@@ -24,18 +24,16 @@
*/
package javax.xml.datatype;
import java.io.File;
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.io.InputStream;
-
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.util.Iterator;
import java.util.Properties;
-import java.io.BufferedReader;
-import java.io.InputStreamReader;
-import java.net.URL;
+import java.util.ServiceConfigurationError;
+import java.util.ServiceLoader;
/**
* <p>Implements pluggable Datatypes.</p>
*
* <p>This class is duplicated for each JAXP subpackage so keep it in
@@ -52,23 +50,23 @@
private static boolean debug = false;
/**
* Cache for properties in java.home/lib/jaxp.properties
*/
- static Properties cacheProps = new Properties();
+ private final static Properties cacheProps = new Properties();
/**
* Flag indicating if properties from java.home/lib/jaxp.properties
* have been cached.
*/
- static volatile boolean firstTime = true;
+ private static volatile boolean firstTime = true;
/**
* Security support class use to check access control before
* getting certain system resources.
*/
- static SecuritySupport ss = new SecuritySupport();
+ private final static SecuritySupport ss = new SecuritySupport();
// Define system property "jaxp.debug" to get output
static {
// Use try/catch block to support applets, which throws
// SecurityException out of this code.
@@ -97,35 +95,35 @@
* context class loader followed by the current (i.e. bootstrap) class
* loader.
*
* Use bootstrap classLoader if cl = null and useBSClsLoader is true
*/
- static private Class getProviderClass(String className, ClassLoader cl,
+ static private Class<?> getProviderClass(String className, ClassLoader cl,
boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
{
try {
if (cl == null) {
if (useBSClsLoader) {
- return Class.forName(className, true, FactoryFinder.class.getClassLoader());
+ return Class.forName(className, false, FactoryFinder.class.getClassLoader());
} else {
cl = ss.getContextClassLoader();
if (cl == null) {
throw new ClassNotFoundException();
}
else {
- return cl.loadClass(className);
+ return Class.forName(className, false, cl);
}
}
}
else {
- return cl.loadClass(className);
+ return Class.forName(className, false, cl);
}
}
catch (ClassNotFoundException e1) {
if (doFallback) {
// Use current class loader - should always be bootstrap CL
- return Class.forName(className, true, FactoryFinder.class.getClassLoader());
+ return Class.forName(className, false, FactoryFinder.class.getClassLoader());
}
else {
throw e1;
}
}
@@ -133,29 +131,35 @@
/**
* Create an instance of a class. Delegates to method
* <code>getProviderClass()</code> in order to load the class.
*
+ * @param type Base class / Service interface of the factory to
+ * instantiate.
+ *
* @param className Name of the concrete class corresponding to the
* service provider
*
* @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
* current <code>Thread</code>'s context classLoader is used to load the factory class.
*
* @param doFallback True if the current ClassLoader should be tried as
* a fallback if the class is not found using cl
*/
- static Object newInstance(String className, ClassLoader cl, boolean doFallback)
- throws ConfigurationError
+ static <T> T newInstance(Class<T> type, String className, ClassLoader cl, boolean doFallback)
+ throws DatatypeConfigurationException
{
- return newInstance(className, cl, doFallback, false);
+ return newInstance(type, className, cl, doFallback, false);
}
/**
* Create an instance of a class. Delegates to method
* <code>getProviderClass()</code> in order to load the class.
*
+ * @param type Base class / Service interface of the factory to
+ * instantiate.
+ *
* @param className Name of the concrete class corresponding to the
* service provider
*
* @param cl ClassLoader to use to load the class, null means to use
* the bootstrap ClassLoader
@@ -164,73 +168,79 @@
* a fallback if the class is not found using cl
*
* @param useBSClsLoader True if cl=null actually meant bootstrap classLoader. This parameter
* is needed since DocumentBuilderFactory/SAXParserFactory defined null as context classLoader.
*/
- static Object newInstance(String className, ClassLoader cl, boolean doFallback, boolean useBSClsLoader)
- throws ConfigurationError
+ static <T> T newInstance(Class<T> type, String className, ClassLoader cl,
+ boolean doFallback, boolean useBSClsLoader)
+ throws DatatypeConfigurationException
{
+ assert type != null;
+
// make sure we have access to restricted packages
if (System.getSecurityManager() != null) {
if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
cl = null;
useBSClsLoader = true;
}
}
try {
- Class providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
+ Class<?> providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
+ if (!type.isAssignableFrom(providerClass)) {
+ throw new ClassCastException(className + " cannot be cast to " + type.getName());
+ }
Object instance = providerClass.newInstance();
if (debug) { // Extra check to avoid computing cl strings
dPrint("created new instance of " + providerClass +
" using ClassLoader: " + cl);
}
- return instance;
+ return type.cast(instance);
}
catch (ClassNotFoundException x) {
- throw new ConfigurationError(
+ throw new DatatypeConfigurationException(
"Provider " + className + " not found", x);
}
catch (Exception x) {
- throw new ConfigurationError(
+ throw new DatatypeConfigurationException(
"Provider " + className + " could not be instantiated: " + x,
x);
}
}
/**
* Finds the implementation Class object in the specified order. Main
* entry point.
* @return Class object of factory, never null
*
- * @param factoryId Name of the factory to find, same as
- * a property name
+ * @param type Base class / Service interface of the
+ * factory to find.
* @param fallbackClassName Implementation class name, if nothing else
* is found. Use null to mean no fallback.
*
* Package private so this code can be shared.
*/
- static Object find(String factoryId, String fallbackClassName)
- throws ConfigurationError
+ static <T> T find(Class<T> type, String fallbackClassName)
+ throws DatatypeConfigurationException
{
+ final String factoryId = type.getName();
dPrint("find factoryId =" + factoryId);
// Use the system property first
try {
String systemProp = ss.getSystemProperty(factoryId);
if (systemProp != null) {
dPrint("found system property, value=" + systemProp);
- return newInstance(systemProp, null, true);
+ return newInstance(type, systemProp, null, true);
}
}
catch (SecurityException se) {
if (debug) se.printStackTrace();
}
// try to read from $java.home/lib/jaxp.properties
try {
- String factoryClassName = null;
if (firstTime) {
synchronized (cacheProps) {
if (firstTime) {
String configFile = ss.getSystemProperty("java.home") + File.separator +
"lib" + File.separator + "jaxp.properties";
@@ -241,127 +251,61 @@
cacheProps.load(ss.getFileInputStream(f));
}
}
}
}
- factoryClassName = cacheProps.getProperty(factoryId);
+ final String factoryClassName = cacheProps.getProperty(factoryId);
if (factoryClassName != null) {
dPrint("found in $java.home/jaxp.properties, value=" + factoryClassName);
- return newInstance(factoryClassName, null, true);
+ return newInstance(type, factoryClassName, null, true);
}
}
catch (Exception ex) {
if (debug) ex.printStackTrace();
}
// Try Jar Service Provider Mechanism
- Object provider = findJarServiceProvider(factoryId);
+ final T provider = findServiceProvider(type);
if (provider != null) {
return provider;
}
if (fallbackClassName == null) {
- throw new ConfigurationError(
- "Provider for " + factoryId + " cannot be found", null);
+ throw new DatatypeConfigurationException(
+ "Provider for " + factoryId + " cannot be found");
}
dPrint("loaded from fallback value: " + fallbackClassName);
- return newInstance(fallbackClassName, null, true);
+ return newInstance(type, fallbackClassName, null, true);
}
/*
- * Try to find provider using Jar Service Provider Mechanism
+ * Try to find provider using the ServiceLoader API
+ *
+ * @param type Base class / Service interface of the factory to find.
*
* @return instance of provider class if found or null
*/
- private static Object findJarServiceProvider(String factoryId)
- throws ConfigurationError
+ private static <T> T findServiceProvider(final Class<T> type)
+ throws DatatypeConfigurationException
{
- String serviceId = "META-INF/services/" + factoryId;
- InputStream is = null;
-
- // First try the Context ClassLoader
- ClassLoader cl = ss.getContextClassLoader();
- boolean useBSClsLoader = false;
- if (cl != null) {
- is = ss.getResourceAsStream(cl, serviceId);
-
- // If no provider found then try the current ClassLoader
- if (is == null) {
- cl = FactoryFinder.class.getClassLoader();
- is = ss.getResourceAsStream(cl, serviceId);
- useBSClsLoader = true;
- }
- } else {
- // No Context ClassLoader, try the current ClassLoader
- cl = FactoryFinder.class.getClassLoader();
- is = ss.getResourceAsStream(cl, serviceId);
- useBSClsLoader = true;
- }
-
- if (is == null) {
- // No provider found
- return null;
- }
-
- if (debug) { // Extra check to avoid computing cl strings
- dPrint("found jar resource=" + serviceId + " using ClassLoader: " + cl);
- }
-
- BufferedReader rd;
try {
- rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));
- }
- catch (java.io.UnsupportedEncodingException e) {
- rd = new BufferedReader(new InputStreamReader(is));
- }
-
- String factoryClassName = null;
- try {
- // XXX Does not handle all possible input as specified by the
- // Jar Service Provider specification
- factoryClassName = rd.readLine();
- rd.close();
- } catch (IOException x) {
- // No provider found
- return null;
- }
-
- if (factoryClassName != null && !"".equals(factoryClassName)) {
- dPrint("found in resource, value=" + factoryClassName);
-
- // Note: here we do not want to fall back to the current
- // ClassLoader because we want to avoid the case where the
- // resource file was found using one ClassLoader and the
- // provider class was instantiated using a different one.
- return newInstance(factoryClassName, cl, false, useBSClsLoader);
- }
-
- // No provider found
+ return AccessController.doPrivileged(new PrivilegedAction<T>() {
+ public T run() {
+ final ServiceLoader<T> serviceLoader = ServiceLoader.load(type);
+ final Iterator<T> iterator = serviceLoader.iterator();
+ if (iterator.hasNext()) {
+ return iterator.next();
+ } else {
return null;
}
-
- static class ConfigurationError extends Error {
- private Exception exception;
-
- /**
- * Construct a new instance with the specified detail string and
- * exception.
- */
- ConfigurationError(String msg, Exception x) {
- super(msg);
- this.exception = x;
}
-
- Exception getException() {
- return exception;
- }
- /**
- * use the exception chaining mechanism of JDK1.4
- */
- @Override
- public Throwable getCause() {
- return exception;
+ });
+ } catch(ServiceConfigurationError e) {
+ final DatatypeConfigurationException error =
+ new DatatypeConfigurationException(
+ "Provider for " + type + " cannot be found", e);
+ throw error;
}
}
}