/*
* @(#)IIORegistry.java 1.65 04/06/17
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.imageio.spi;
import java.security.PrivilegedAction;
import java.security.AccessController;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.Vector;
import com.sun.imageio.spi.FileImageInputStreamSpi;
import com.sun.imageio.spi.FileImageOutputStreamSpi;
import com.sun.imageio.spi.InputStreamImageInputStreamSpi;
import com.sun.imageio.spi.OutputStreamImageOutputStreamSpi;
import com.sun.imageio.spi.RAFImageInputStreamSpi;
import com.sun.imageio.spi.RAFImageOutputStreamSpi;
import com.sun.imageio.plugins.gif.GIFImageReaderSpi;
import com.sun.imageio.plugins.gif.GIFImageWriterSpi;
import com.sun.imageio.plugins.jpeg.JPEGImageReaderSpi;
import com.sun.imageio.plugins.jpeg.JPEGImageWriterSpi;
import com.sun.imageio.plugins.png.PNGImageReaderSpi;
import com.sun.imageio.plugins.png.PNGImageWriterSpi;
import com.sun.imageio.plugins.bmp.BMPImageReaderSpi;
import com.sun.imageio.plugins.bmp.BMPImageWriterSpi;
import com.sun.imageio.plugins.wbmp.WBMPImageReaderSpi;
import com.sun.imageio.plugins.wbmp.WBMPImageWriterSpi;
import sun.awt.AppContext;
import sun.misc.Service;
import sun.misc.ServiceConfigurationError;
/**
* A registry for service provider instances. Service provider
* classes may be detected at run time by means of meta-information in
* the JAR files containing them. The intent is that it be relatively
* inexpensive to load and inspect all available service provider
* classes. These classes may them be used to locate and instantiate
* more heavyweight classes that will perform actual work, in this
* case instances of <code>ImageReader</code>,
* <code>ImageWriter</code>, <code>ImageTranscoder</code>,
* <code>ImageInputStream</code>, and <code>ImageOutputStream</code>.
*
* <p> Service providers found on the system classpath (<i>e.g.</i>,
* the <code>jre/lib/ext</code> directory in Sun's implementation of
* JDK) are automatically loaded as soon as this class is
* instantiated.
*
* <p> When the <code>registerApplicationClasspathSpis</code> method
* is called, service provider instances declared in the
* meta-information section of JAR files on the application class path
* are loaded. To declare a service provider, a <code>services</code>
* subdirectory is placed within the <code>META-INF</code> directory
* that is present in every JAR file. This directory contains a file
* for each service provider interface that has one or more
* implementation classes present in the JAR file. For example, if
* the JAR file contained a class named
* <code>com.mycompany.imageio.MyFormatReaderSpi</code> which
* implements the <code>ImageReaderSpi</code> interface, the JAR file
* would contain a file named:
*
* <pre>
* META-INF/services/javax.imageio.spi.ImageReaderSpi
* </pre>
*
* containing the line:
*
* <pre>
* com.mycompany.imageio.MyFormatReaderSpi
* </pre>
*
* <p> The service provider classes are intended to be lightweight
* and quick to load. Implementations of these interfaces
* should avoid complex dependencies on other classes and on
* native code.
*
* <p> It is also possible to manually add service providers not found
* automatically, as well as to remove those that are using the
* interfaces of the <code>ServiceRegistry</code> class. Thus
* the application may customize the contents of the registry as it
* sees fit.
*
* <p> For more details on declaring service providers, and the JAR
* format in general, see the <a
* href="{@docRoot}/../technotes/guides/jar/jar.html">
* JAR File Specification</a>.
*
* @version 0.5
*/
public final class IIORegistry extends ServiceRegistry {
/**
* A <code>Vector</code> containing the valid IIO registry
* categories (superinterfaces) to be used in the constructor.
*/
private static final Vector initialCategories = new Vector(5);
static {
initialCategories.add(ImageReaderSpi.class);
initialCategories.add(ImageWriterSpi.class);
initialCategories.add(ImageTranscoderSpi.class);
initialCategories.add(ImageInputStreamSpi.class);
initialCategories.add(ImageOutputStreamSpi.class);
}
/**
* Set up the valid service provider categories and automatically
* register all available service providers.
*
* <p> The constructor is private in order to prevent creation of
* additional instances.
*/
private IIORegistry() {
super(initialCategories.iterator());
registerStandardSpis();
registerApplicationClasspathSpis();
}
/**
* Returns the default <code>IIORegistry</code> instance used by
* the Image I/O API. This instance should be used for all
* registry functions.
*
* <p> Each <code>ThreadGroup</code> will receive its own
* instance; this allows different <code>Applet</code>s in the
* same browser (for example) to each have their own registry.
*
* @return the default registry for the current
* <code>ThreadGroup</code>.
*/
public static IIORegistry getDefaultInstance() {
AppContext context = AppContext.getAppContext();
IIORegistry registry =
(IIORegistry)context.get(IIORegistry.class);
if (registry == null) {
// Create an instance for this AppContext
registry = new IIORegistry();
context.put(IIORegistry.class, registry);
}
return registry;
}
private void registerStandardSpis() {
// Hardwire standard SPIs
registerServiceProvider(new GIFImageReaderSpi());
registerServiceProvider(new GIFImageWriterSpi());
registerServiceProvider(new BMPImageReaderSpi());
registerServiceProvider(new BMPImageWriterSpi());
registerServiceProvider(new WBMPImageReaderSpi());
registerServiceProvider(new WBMPImageWriterSpi());
registerServiceProvider(new PNGImageReaderSpi());
registerServiceProvider(new PNGImageWriterSpi());
registerServiceProvider(new JPEGImageReaderSpi());
registerServiceProvider(new JPEGImageWriterSpi());
registerServiceProvider(new FileImageInputStreamSpi());
registerServiceProvider(new FileImageOutputStreamSpi());
registerServiceProvider(new InputStreamImageInputStreamSpi());
registerServiceProvider(new OutputStreamImageOutputStreamSpi());
registerServiceProvider(new RAFImageInputStreamSpi());
registerServiceProvider(new RAFImageOutputStreamSpi());
registerInstalledProviders();
}
/**
* Registers all available service providers found on the
* application class path, using the default
* <code>ClassLoader</code>. This method is typically invoked by
* the <code>ImageIO.scanForPlugins</code> method.
*
* @see javax.imageio.ImageIO#scanForPlugins
* @see ClassLoader#getResources
*/
public void registerApplicationClasspathSpis() {
// FIX: load only from application classpath
ClassLoader loader = Thread.currentThread().getContextClassLoader();
Iterator categories = getCategories();
while (categories.hasNext()) {
Class c = (Class)categories.next();
Iterator<IIOServiceProvider> riter = Service.providers(c, loader);
while (riter.hasNext()) {
try {
IIOServiceProvider r = riter.next();
registerServiceProvider(r);
} catch (ServiceConfigurationError err) {
if (System.getSecurityManager() != null) {
// In the applet case, we will catch the error so
// registration of other plugins can proceed
err.printStackTrace();
} else {
// In the application case, we will throw the
// error to indicate app/system misconfiguration
throw err;
}
}
}
}
}
private void registerInstalledProviders() {
/*
We need load installed providers from lib/ext
directory in the privileged mode in order to
be able read corresponding jar files even if
file read capability is restricted (like the
applet context case).
*/
PrivilegedAction doRegistration =
new PrivilegedAction() {
public Object run() {
Iterator categories = getCategories();
while (categories.hasNext()) {
Class c = (Class)categories.next();
Iterator<IIOServiceProvider> providers =
Service.installedProviders(c);
while (providers.hasNext()) {
IIOServiceProvider p = providers.next();
registerServiceProvider(p);
}
}
return this;
}
};
AccessController.doPrivileged(doRegistration);
}
}
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