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The ImageIO.java Java example source code
/*
* Copyright (c) 2000, 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
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.imageio;
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.FilePermission;
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.reflect.Method;
import java.net.URL;
import java.security.AccessController;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
import javax.imageio.spi.IIORegistry;
import javax.imageio.spi.ImageReaderSpi;
import javax.imageio.spi.ImageReaderWriterSpi;
import javax.imageio.spi.ImageWriterSpi;
import javax.imageio.spi.ImageInputStreamSpi;
import javax.imageio.spi.ImageOutputStreamSpi;
import javax.imageio.spi.ImageTranscoderSpi;
import javax.imageio.spi.ServiceRegistry;
import javax.imageio.stream.ImageInputStream;
import javax.imageio.stream.ImageOutputStream;
import sun.awt.AppContext;
import sun.security.action.GetPropertyAction;
/**
* A class containing static convenience methods for locating
* <code>ImageReaders and ImageWriters, and
* performing simple encoding and decoding.
*
*/
public final class ImageIO {
private static final IIORegistry theRegistry =
IIORegistry.getDefaultInstance();
/**
* Constructor is private to prevent instantiation.
*/
private ImageIO() {}
/**
* Scans for plug-ins on the application class path,
* loads their service provider classes, and registers a service
* provider instance for each one found with the
* <code>IIORegistry.
*
* <p>This method is needed because the application class path can
* theoretically change, or additional plug-ins may become available.
* Rather than re-scanning the classpath on every invocation of the
* API, the class path is scanned automatically only on the first
* invocation. Clients can call this method to prompt a re-scan.
* Thus this method need only be invoked by sophisticated applications
* which dynamically make new plug-ins available at runtime.
*
* <p> The getResources method of the context
* <code>ClassLoader is used locate JAR files containing
* files named
* <code>META-INF/services/javax.imageio.spi.classname,
* where <i>classname is one of ImageReaderSpi,
* <code>ImageWriterSpi, ImageTranscoderSpi,
* <code>ImageInputStreamSpi, or
* <code>ImageOutputStreamSpi, along the application class
* path.
*
* <p> The contents of the located files indicate the names of
* actual implementation classes which implement the
* aforementioned service provider interfaces; the default class
* loader is then used to load each of these classes and to
* instantiate an instance of each class, which is then placed
* into the registry for later retrieval.
*
* <p> The exact set of locations searched depends on the
* implementation of the Java runtime environment.
*
* @see ClassLoader#getResources
*/
public static void scanForPlugins() {
theRegistry.registerApplicationClasspathSpis();
}
// ImageInputStreams
/**
* A class to hold information about caching. Each
* <code>ThreadGroup will have its own copy
* via the <code>AppContext mechanism.
*/
static class CacheInfo {
boolean useCache = true;
File cacheDirectory = null;
Boolean hasPermission = null;
public CacheInfo() {}
public boolean getUseCache() {
return useCache;
}
public void setUseCache(boolean useCache) {
this.useCache = useCache;
}
public File getCacheDirectory() {
return cacheDirectory;
}
public void setCacheDirectory(File cacheDirectory) {
this.cacheDirectory = cacheDirectory;
}
public Boolean getHasPermission() {
return hasPermission;
}
public void setHasPermission(Boolean hasPermission) {
this.hasPermission = hasPermission;
}
}
/**
* Returns the <code>CacheInfo object associated with this
* <code>ThreadGroup.
*/
private static synchronized CacheInfo getCacheInfo() {
AppContext context = AppContext.getAppContext();
CacheInfo info = (CacheInfo)context.get(CacheInfo.class);
if (info == null) {
info = new CacheInfo();
context.put(CacheInfo.class, info);
}
return info;
}
/**
* Returns the default temporary (cache) directory as defined by the
* java.io.tmpdir system property.
*/
private static String getTempDir() {
GetPropertyAction a = new GetPropertyAction("java.io.tmpdir");
return (String)AccessController.doPrivileged(a);
}
/**
* Determines whether the caller has write access to the cache
* directory, stores the result in the <code>CacheInfo object,
* and returns the decision. This method helps to prevent mysterious
* SecurityExceptions to be thrown when this convenience class is used
* in an applet, for example.
*/
private static boolean hasCachePermission() {
Boolean hasPermission = getCacheInfo().getHasPermission();
if (hasPermission != null) {
return hasPermission.booleanValue();
} else {
try {
SecurityManager security = System.getSecurityManager();
if (security != null) {
File cachedir = getCacheDirectory();
String cachepath;
if (cachedir != null) {
cachepath = cachedir.getPath();
} else {
cachepath = getTempDir();
if (cachepath == null || cachepath.isEmpty()) {
getCacheInfo().setHasPermission(Boolean.FALSE);
return false;
}
}
// we have to check whether we can read, write,
// and delete cache files.
// So, compose cache file path and check it.
String filepath = cachepath;
if (!filepath.endsWith(File.separator)) {
filepath += File.separator;
}
filepath += "*";
security.checkPermission(new FilePermission(filepath, "read, write, delete"));
}
} catch (SecurityException e) {
getCacheInfo().setHasPermission(Boolean.FALSE);
return false;
}
getCacheInfo().setHasPermission(Boolean.TRUE);
return true;
}
}
/**
* Sets a flag indicating whether a disk-based cache file should
* be used when creating <code>ImageInputStreams and
* <code>ImageOutputStreams.
*
* <p> When reading from a standard InputStream, it
* may be necessary to save previously read information in a cache
* since the underlying stream does not allow data to be re-read.
* Similarly, when writing to a standard
* <code>OutputStream, a cache may be used to allow a
* previously written value to be changed before flushing it to
* the final destination.
*
* <p> The cache may reside in main memory or on disk. Setting
* this flag to <code>false disallows the use of disk for
* future streams, which may be advantageous when working with
* small images, as the overhead of creating and destroying files
* is removed.
*
* <p> On startup, the value is set to true.
*
* @param useCache a <code>boolean indicating whether a
* cache file should be used, in cases where it is optional.
*
* @see #getUseCache
*/
public static void setUseCache(boolean useCache) {
getCacheInfo().setUseCache(useCache);
}
/**
* Returns the current value set by <code>setUseCache, or
* <code>true if no explicit setting has been made.
*
* @return true if a disk-based cache may be used for
* <code>ImageInputStreams and
* <code>ImageOutputStreams.
*
* @see #setUseCache
*/
public static boolean getUseCache() {
return getCacheInfo().getUseCache();
}
/**
* Sets the directory where cache files are to be created. A
* value of <code>null indicates that the system-dependent
* default temporary-file directory is to be used. If
* <code>getUseCache returns false, this value is ignored.
*
* @param cacheDirectory a <code>File specifying a directory.
*
* @see File#createTempFile(String, String, File)
*
* @exception SecurityException if the security manager denies
* access to the directory.
* @exception IllegalArgumentException if <code>cacheDir is
* non-<code>null but is not a directory.
*
* @see #getCacheDirectory
*/
public static void setCacheDirectory(File cacheDirectory) {
if ((cacheDirectory != null) && !(cacheDirectory.isDirectory())) {
throw new IllegalArgumentException("Not a directory!");
}
getCacheInfo().setCacheDirectory(cacheDirectory);
getCacheInfo().setHasPermission(null);
}
/**
* Returns the current value set by
* <code>setCacheDirectory, or null if no
* explicit setting has been made.
*
* @return a <code>File indicating the directory where
* cache files will be created, or <code>null to indicate
* the system-dependent default temporary-file directory.
*
* @see #setCacheDirectory
*/
public static File getCacheDirectory() {
return getCacheInfo().getCacheDirectory();
}
/**
* Returns an <code>ImageInputStream that will take its
* input from the given <code>Object. The set of
* <code>ImageInputStreamSpis registered with the
* <code>IIORegistry class is queried and the first one
* that is able to take input from the supplied object is used to
* create the returned <code>ImageInputStream. If no
* suitable <code>ImageInputStreamSpi exists,
* <code>null is returned.
*
* <p> The current cache settings from getUseCacheand
* <code>getCacheDirectory will be used to control caching.
*
* @param input an <code>Object to be used as an input
* source, such as a <code>File, readable
* <code>RandomAccessFile, or InputStream.
*
* @return an <code>ImageInputStream, or null.
*
* @exception IllegalArgumentException if <code>input
* is <code>null.
* @exception IOException if a cache file is needed but cannot be
* created.
*
* @see javax.imageio.spi.ImageInputStreamSpi
*/
public static ImageInputStream createImageInputStream(Object input)
throws IOException {
if (input == null) {
throw new IllegalArgumentException("input == null!");
}
Iterator iter;
// Ensure category is present
try {
iter = theRegistry.getServiceProviders(ImageInputStreamSpi.class,
true);
} catch (IllegalArgumentException e) {
return null;
}
boolean usecache = getUseCache() && hasCachePermission();
while (iter.hasNext()) {
ImageInputStreamSpi spi = (ImageInputStreamSpi)iter.next();
if (spi.getInputClass().isInstance(input)) {
try {
return spi.createInputStreamInstance(input,
usecache,
getCacheDirectory());
} catch (IOException e) {
throw new IIOException("Can't create cache file!", e);
}
}
}
return null;
}
// ImageOutputStreams
/**
* Returns an <code>ImageOutputStream that will send its
* output to the given <code>Object. The set of
* <code>ImageOutputStreamSpis registered with the
* <code>IIORegistry class is queried and the first one
* that is able to send output from the supplied object is used to
* create the returned <code>ImageOutputStream. If no
* suitable <code>ImageOutputStreamSpi exists,
* <code>null is returned.
*
* <p> The current cache settings from getUseCacheand
* <code>getCacheDirectory will be used to control caching.
*
* @param output an <code>Object to be used as an output
* destination, such as a <code>File, writable
* <code>RandomAccessFile, or OutputStream.
*
* @return an <code>ImageOutputStream, or
* <code>null.
*
* @exception IllegalArgumentException if <code>output is
* <code>null.
* @exception IOException if a cache file is needed but cannot be
* created.
*
* @see javax.imageio.spi.ImageOutputStreamSpi
*/
public static ImageOutputStream createImageOutputStream(Object output)
throws IOException {
if (output == null) {
throw new IllegalArgumentException("output == null!");
}
Iterator iter;
// Ensure category is present
try {
iter = theRegistry.getServiceProviders(ImageOutputStreamSpi.class,
true);
} catch (IllegalArgumentException e) {
return null;
}
boolean usecache = getUseCache() && hasCachePermission();
while (iter.hasNext()) {
ImageOutputStreamSpi spi = (ImageOutputStreamSpi)iter.next();
if (spi.getOutputClass().isInstance(output)) {
try {
return spi.createOutputStreamInstance(output,
usecache,
getCacheDirectory());
} catch (IOException e) {
throw new IIOException("Can't create cache file!", e);
}
}
}
return null;
}
private static enum SpiInfo {
FORMAT_NAMES {
@Override
String[] info(ImageReaderWriterSpi spi) {
return spi.getFormatNames();
}
},
MIME_TYPES {
@Override
String[] info(ImageReaderWriterSpi spi) {
return spi.getMIMETypes();
}
},
FILE_SUFFIXES {
@Override
String[] info(ImageReaderWriterSpi spi) {
return spi.getFileSuffixes();
}
};
abstract String[] info(ImageReaderWriterSpi spi);
}
private static <S extends ImageReaderWriterSpi>
String[] getReaderWriterInfo(Class<S> spiClass, SpiInfo spiInfo)
{
// Ensure category is present
Iterator<S> iter;
try {
iter = theRegistry.getServiceProviders(spiClass, true);
} catch (IllegalArgumentException e) {
return new String[0];
}
HashSet<String> s = new HashSet();
while (iter.hasNext()) {
ImageReaderWriterSpi spi = iter.next();
Collections.addAll(s, spiInfo.info(spi));
}
return s.toArray(new String[s.size()]);
}
// Readers
/**
* Returns an array of <code>Strings listing all of the
* informal format names understood by the current set of registered
* readers.
*
* @return an array of <code>Strings.
*/
public static String[] getReaderFormatNames() {
return getReaderWriterInfo(ImageReaderSpi.class,
SpiInfo.FORMAT_NAMES);
}
/**
* Returns an array of <code>Strings listing all of the
* MIME types understood by the current set of registered
* readers.
*
* @return an array of <code>Strings.
*/
public static String[] getReaderMIMETypes() {
return getReaderWriterInfo(ImageReaderSpi.class,
SpiInfo.MIME_TYPES);
}
/**
* Returns an array of <code>Strings listing all of the
* file suffixes associated with the formats understood
* by the current set of registered readers.
*
* @return an array of <code>Strings.
* @since 1.6
*/
public static String[] getReaderFileSuffixes() {
return getReaderWriterInfo(ImageReaderSpi.class,
SpiInfo.FILE_SUFFIXES);
}
static class ImageReaderIterator implements Iterator<ImageReader> {
// Contains ImageReaderSpis
public Iterator iter;
public ImageReaderIterator(Iterator iter) {
this.iter = iter;
}
public boolean hasNext() {
return iter.hasNext();
}
public ImageReader next() {
ImageReaderSpi spi = null;
try {
spi = (ImageReaderSpi)iter.next();
return spi.createReaderInstance();
} catch (IOException e) {
// Deregister the spi in this case, but only as
// an ImageReaderSpi
theRegistry.deregisterServiceProvider(spi, ImageReaderSpi.class);
}
return null;
}
public void remove() {
throw new UnsupportedOperationException();
}
}
static class CanDecodeInputFilter
implements ServiceRegistry.Filter {
Object input;
public CanDecodeInputFilter(Object input) {
this.input = input;
}
public boolean filter(Object elt) {
try {
ImageReaderSpi spi = (ImageReaderSpi)elt;
ImageInputStream stream = null;
if (input instanceof ImageInputStream) {
stream = (ImageInputStream)input;
}
// Perform mark/reset as a defensive measure
// even though plug-ins are supposed to take
// care of it.
boolean canDecode = false;
if (stream != null) {
stream.mark();
}
canDecode = spi.canDecodeInput(input);
if (stream != null) {
stream.reset();
}
return canDecode;
} catch (IOException e) {
return false;
}
}
}
static class CanEncodeImageAndFormatFilter
implements ServiceRegistry.Filter {
ImageTypeSpecifier type;
String formatName;
public CanEncodeImageAndFormatFilter(ImageTypeSpecifier type,
String formatName) {
this.type = type;
this.formatName = formatName;
}
public boolean filter(Object elt) {
ImageWriterSpi spi = (ImageWriterSpi)elt;
return Arrays.asList(spi.getFormatNames()).contains(formatName) &&
spi.canEncodeImage(type);
}
}
static class ContainsFilter
implements ServiceRegistry.Filter {
Method method;
String name;
// method returns an array of Strings
public ContainsFilter(Method method,
String name) {
this.method = method;
this.name = name;
}
public boolean filter(Object elt) {
try {
return contains((String[])method.invoke(elt), name);
} catch (Exception e) {
return false;
}
}
}
/**
* Returns an <code>Iterator containing all currently
* registered <code>ImageReaders that claim to be able to
* decode the supplied <code>Object, typically an
* <code>ImageInputStream.
*
* <p> The stream position is left at its prior position upon
* exit from this method.
*
* @param input an <code>ImageInputStream or other
* <code>Object containing encoded image data.
*
* @return an <code>Iterator containing ImageReaders.
*
* @exception IllegalArgumentException if <code>input is
* <code>null.
*
* @see javax.imageio.spi.ImageReaderSpi#canDecodeInput
*/
public static Iterator<ImageReader> getImageReaders(Object input) {
if (input == null) {
throw new IllegalArgumentException("input == null!");
}
Iterator iter;
// Ensure category is present
try {
iter = theRegistry.getServiceProviders(ImageReaderSpi.class,
new CanDecodeInputFilter(input),
true);
} catch (IllegalArgumentException e) {
return Collections.emptyIterator();
}
return new ImageReaderIterator(iter);
}
private static Method readerFormatNamesMethod;
private static Method readerFileSuffixesMethod;
private static Method readerMIMETypesMethod;
private static Method writerFormatNamesMethod;
private static Method writerFileSuffixesMethod;
private static Method writerMIMETypesMethod;
static {
try {
readerFormatNamesMethod =
ImageReaderSpi.class.getMethod("getFormatNames");
readerFileSuffixesMethod =
ImageReaderSpi.class.getMethod("getFileSuffixes");
readerMIMETypesMethod =
ImageReaderSpi.class.getMethod("getMIMETypes");
writerFormatNamesMethod =
ImageWriterSpi.class.getMethod("getFormatNames");
writerFileSuffixesMethod =
ImageWriterSpi.class.getMethod("getFileSuffixes");
writerMIMETypesMethod =
ImageWriterSpi.class.getMethod("getMIMETypes");
} catch (NoSuchMethodException e) {
e.printStackTrace();
}
}
/**
* Returns an <code>Iterator containing all currently
* registered <code>ImageReaders that claim to be able to
* decode the named format.
*
* @param formatName a <code>String containing the informal
* name of a format (<i>e.g., "jpeg" or "tiff".
*
* @return an <code>Iterator containing
* <code>ImageReaders.
*
* @exception IllegalArgumentException if <code>formatName
* is <code>null.
*
* @see javax.imageio.spi.ImageReaderSpi#getFormatNames
*/
public static Iterator<ImageReader>
getImageReadersByFormatName(String formatName)
{
if (formatName == null) {
throw new IllegalArgumentException("formatName == null!");
}
Iterator iter;
// Ensure category is present
try {
iter = theRegistry.getServiceProviders(ImageReaderSpi.class,
new ContainsFilter(readerFormatNamesMethod,
formatName),
true);
} catch (IllegalArgumentException e) {
return Collections.emptyIterator();
}
return new ImageReaderIterator(iter);
}
/**
* Returns an <code>Iterator containing all currently
* registered <code>ImageReaders that claim to be able to
* decode files with the given suffix.
*
* @param fileSuffix a <code>String containing a file
* suffix (<i>e.g., "jpg" or "tiff").
*
* @return an <code>Iterator containing
* <code>ImageReaders.
*
* @exception IllegalArgumentException if <code>fileSuffix
* is <code>null.
*
* @see javax.imageio.spi.ImageReaderSpi#getFileSuffixes
*/
public static Iterator<ImageReader>
getImageReadersBySuffix(String fileSuffix)
{
if (fileSuffix == null) {
throw new IllegalArgumentException("fileSuffix == null!");
}
// Ensure category is present
Iterator iter;
try {
iter = theRegistry.getServiceProviders(ImageReaderSpi.class,
new ContainsFilter(readerFileSuffixesMethod,
fileSuffix),
true);
} catch (IllegalArgumentException e) {
return Collections.emptyIterator();
}
return new ImageReaderIterator(iter);
}
/**
* Returns an <code>Iterator containing all currently
* registered <code>ImageReaders that claim to be able to
* decode files with the given MIME type.
*
* @param MIMEType a <code>String containing a file
* suffix (<i>e.g., "image/jpeg" or "image/x-bmp").
*
* @return an <code>Iterator containing
* <code>ImageReaders.
*
* @exception IllegalArgumentException if <code>MIMEType is
* <code>null.
*
* @see javax.imageio.spi.ImageReaderSpi#getMIMETypes
*/
public static Iterator<ImageReader>
getImageReadersByMIMEType(String MIMEType)
{
if (MIMEType == null) {
throw new IllegalArgumentException("MIMEType == null!");
}
// Ensure category is present
Iterator iter;
try {
iter = theRegistry.getServiceProviders(ImageReaderSpi.class,
new ContainsFilter(readerMIMETypesMethod,
MIMEType),
true);
} catch (IllegalArgumentException e) {
return Collections.emptyIterator();
}
return new ImageReaderIterator(iter);
}
// Writers
/**
* Returns an array of <code>Strings listing all of the
* informal format names understood by the current set of registered
* writers.
*
* @return an array of <code>Strings.
*/
public static String[] getWriterFormatNames() {
return getReaderWriterInfo(ImageWriterSpi.class,
SpiInfo.FORMAT_NAMES);
}
/**
* Returns an array of <code>Strings listing all of the
* MIME types understood by the current set of registered
* writers.
*
* @return an array of <code>Strings.
*/
public static String[] getWriterMIMETypes() {
return getReaderWriterInfo(ImageWriterSpi.class,
SpiInfo.MIME_TYPES);
}
/**
* Returns an array of <code>Strings listing all of the
* file suffixes associated with the formats understood
* by the current set of registered writers.
*
* @return an array of <code>Strings.
* @since 1.6
*/
public static String[] getWriterFileSuffixes() {
return getReaderWriterInfo(ImageWriterSpi.class,
SpiInfo.FILE_SUFFIXES);
}
static class ImageWriterIterator implements Iterator<ImageWriter> {
// Contains ImageWriterSpis
public Iterator iter;
public ImageWriterIterator(Iterator iter) {
this.iter = iter;
}
public boolean hasNext() {
return iter.hasNext();
}
public ImageWriter next() {
ImageWriterSpi spi = null;
try {
spi = (ImageWriterSpi)iter.next();
return spi.createWriterInstance();
} catch (IOException e) {
// Deregister the spi in this case, but only as a writerSpi
theRegistry.deregisterServiceProvider(spi, ImageWriterSpi.class);
}
return null;
}
public void remove() {
throw new UnsupportedOperationException();
}
}
private static boolean contains(String[] names, String name) {
for (int i = 0; i < names.length; i++) {
if (name.equalsIgnoreCase(names[i])) {
return true;
}
}
return false;
}
/**
* Returns an <code>Iterator containing all currently
* registered <code>ImageWriters that claim to be able to
* encode the named format.
*
* @param formatName a <code>String containing the informal
* name of a format (<i>e.g., "jpeg" or "tiff".
*
* @return an <code>Iterator containing
* <code>ImageWriters.
*
* @exception IllegalArgumentException if <code>formatName is
* <code>null.
*
* @see javax.imageio.spi.ImageWriterSpi#getFormatNames
*/
public static Iterator<ImageWriter>
getImageWritersByFormatName(String formatName)
{
if (formatName == null) {
throw new IllegalArgumentException("formatName == null!");
}
Iterator iter;
// Ensure category is present
try {
iter = theRegistry.getServiceProviders(ImageWriterSpi.class,
new ContainsFilter(writerFormatNamesMethod,
formatName),
true);
} catch (IllegalArgumentException e) {
return Collections.emptyIterator();
}
return new ImageWriterIterator(iter);
}
/**
* Returns an <code>Iterator containing all currently
* registered <code>ImageWriters that claim to be able to
* encode files with the given suffix.
*
* @param fileSuffix a <code>String containing a file
* suffix (<i>e.g., "jpg" or "tiff").
*
* @return an <code>Iterator containing ImageWriters.
*
* @exception IllegalArgumentException if <code>fileSuffix is
* <code>null.
*
* @see javax.imageio.spi.ImageWriterSpi#getFileSuffixes
*/
public static Iterator<ImageWriter>
getImageWritersBySuffix(String fileSuffix)
{
if (fileSuffix == null) {
throw new IllegalArgumentException("fileSuffix == null!");
}
Iterator iter;
// Ensure category is present
try {
iter = theRegistry.getServiceProviders(ImageWriterSpi.class,
new ContainsFilter(writerFileSuffixesMethod,
fileSuffix),
true);
} catch (IllegalArgumentException e) {
return Collections.emptyIterator();
}
return new ImageWriterIterator(iter);
}
/**
* Returns an <code>Iterator containing all currently
* registered <code>ImageWriters that claim to be able to
* encode files with the given MIME type.
*
* @param MIMEType a <code>String containing a file
* suffix (<i>e.g., "image/jpeg" or "image/x-bmp").
*
* @return an <code>Iterator containing ImageWriters.
*
* @exception IllegalArgumentException if <code>MIMEType is
* <code>null.
*
* @see javax.imageio.spi.ImageWriterSpi#getMIMETypes
*/
public static Iterator<ImageWriter>
getImageWritersByMIMEType(String MIMEType)
{
if (MIMEType == null) {
throw new IllegalArgumentException("MIMEType == null!");
}
Iterator iter;
// Ensure category is present
try {
iter = theRegistry.getServiceProviders(ImageWriterSpi.class,
new ContainsFilter(writerMIMETypesMethod,
MIMEType),
true);
} catch (IllegalArgumentException e) {
return Collections.emptyIterator();
}
return new ImageWriterIterator(iter);
}
/**
* Returns an <code>ImageWritercorresponding to the given
* <code>ImageReader, if there is one, or null
* if the plug-in for this <code>ImageReader does not
* specify a corresponding <code>ImageWriter, or if the
* given <code>ImageReader is not registered. This
* mechanism may be used to obtain an <code>ImageWriter
* that will understand the internal structure of non-pixel
* metadata (as encoded by <code>IIOMetadata objects)
* generated by the <code>ImageReader. By obtaining this
* data from the <code>ImageReader and passing it on to the
* <code>ImageWriter obtained with this method, a client
* program can read an image, modify it in some way, and write it
* back out preserving all metadata, without having to understand
* anything about the structure of the metadata, or even about
* the image format. Note that this method returns the
* "preferred" writer, which is the first in the list returned by
* <code>javax.imageio.spi.ImageReaderSpi.getImageWriterSpiNames().
*
* @param reader an instance of a registered <code>ImageReader.
*
* @return an <code>ImageWriter, or null.
*
* @exception IllegalArgumentException if <code>reader is
* <code>null.
*
* @see #getImageReader(ImageWriter)
* @see javax.imageio.spi.ImageReaderSpi#getImageWriterSpiNames()
*/
public static ImageWriter getImageWriter(ImageReader reader) {
if (reader == null) {
throw new IllegalArgumentException("reader == null!");
}
ImageReaderSpi readerSpi = reader.getOriginatingProvider();
if (readerSpi == null) {
Iterator readerSpiIter;
// Ensure category is present
try {
readerSpiIter =
theRegistry.getServiceProviders(ImageReaderSpi.class,
false);
} catch (IllegalArgumentException e) {
return null;
}
while (readerSpiIter.hasNext()) {
ImageReaderSpi temp = (ImageReaderSpi) readerSpiIter.next();
if (temp.isOwnReader(reader)) {
readerSpi = temp;
break;
}
}
if (readerSpi == null) {
return null;
}
}
String[] writerNames = readerSpi.getImageWriterSpiNames();
if (writerNames == null) {
return null;
}
Class writerSpiClass = null;
try {
writerSpiClass = Class.forName(writerNames[0], true,
ClassLoader.getSystemClassLoader());
} catch (ClassNotFoundException e) {
return null;
}
ImageWriterSpi writerSpi = (ImageWriterSpi)
theRegistry.getServiceProviderByClass(writerSpiClass);
if (writerSpi == null) {
return null;
}
try {
return writerSpi.createWriterInstance();
} catch (IOException e) {
// Deregister the spi in this case, but only as a writerSpi
theRegistry.deregisterServiceProvider(writerSpi,
ImageWriterSpi.class);
return null;
}
}
/**
* Returns an <code>ImageReadercorresponding to the given
* <code>ImageWriter, if there is one, or null
* if the plug-in for this <code>ImageWriter does not
* specify a corresponding <code>ImageReader, or if the
* given <code>ImageWriter is not registered. This method
* is provided principally for symmetry with
* <code>getImageWriter(ImageReader). Note that this
* method returns the "preferred" reader, which is the first in
* the list returned by
* javax.imageio.spi.ImageWriterSpi.<code>getImageReaderSpiNames().
*
* @param writer an instance of a registered <code>ImageWriter.
*
* @return an <code>ImageReader, or null.
*
* @exception IllegalArgumentException if <code>writer is
* <code>null.
*
* @see #getImageWriter(ImageReader)
* @see javax.imageio.spi.ImageWriterSpi#getImageReaderSpiNames()
*/
public static ImageReader getImageReader(ImageWriter writer) {
if (writer == null) {
throw new IllegalArgumentException("writer == null!");
}
ImageWriterSpi writerSpi = writer.getOriginatingProvider();
if (writerSpi == null) {
Iterator writerSpiIter;
// Ensure category is present
try {
writerSpiIter =
theRegistry.getServiceProviders(ImageWriterSpi.class,
false);
} catch (IllegalArgumentException e) {
return null;
}
while (writerSpiIter.hasNext()) {
ImageWriterSpi temp = (ImageWriterSpi) writerSpiIter.next();
if (temp.isOwnWriter(writer)) {
writerSpi = temp;
break;
}
}
if (writerSpi == null) {
return null;
}
}
String[] readerNames = writerSpi.getImageReaderSpiNames();
if (readerNames == null) {
return null;
}
Class readerSpiClass = null;
try {
readerSpiClass = Class.forName(readerNames[0], true,
ClassLoader.getSystemClassLoader());
} catch (ClassNotFoundException e) {
return null;
}
ImageReaderSpi readerSpi = (ImageReaderSpi)
theRegistry.getServiceProviderByClass(readerSpiClass);
if (readerSpi == null) {
return null;
}
try {
return readerSpi.createReaderInstance();
} catch (IOException e) {
// Deregister the spi in this case, but only as a readerSpi
theRegistry.deregisterServiceProvider(readerSpi,
ImageReaderSpi.class);
return null;
}
}
/**
* Returns an <code>Iterator containing all currently
* registered <code>ImageWriters that claim to be able to
* encode images of the given layout (specified using an
* <code>ImageTypeSpecifier) in the given format.
*
* @param type an <code>ImageTypeSpecifier indicating the
* layout of the image to be written.
* @param formatName the informal name of the <code>format.
*
* @return an <code>Iterator containing ImageWriters.
*
* @exception IllegalArgumentException if any parameter is
* <code>null.
*
* @see javax.imageio.spi.ImageWriterSpi#canEncodeImage(ImageTypeSpecifier)
*/
public static Iterator<ImageWriter>
getImageWriters(ImageTypeSpecifier type, String formatName)
{
if (type == null) {
throw new IllegalArgumentException("type == null!");
}
if (formatName == null) {
throw new IllegalArgumentException("formatName == null!");
}
Iterator iter;
// Ensure category is present
try {
iter = theRegistry.getServiceProviders(ImageWriterSpi.class,
new CanEncodeImageAndFormatFilter(type,
formatName),
true);
} catch (IllegalArgumentException e) {
return Collections.emptyIterator();
}
return new ImageWriterIterator(iter);
}
static class ImageTranscoderIterator
implements Iterator<ImageTranscoder>
{
// Contains ImageTranscoderSpis
public Iterator iter;
public ImageTranscoderIterator(Iterator iter) {
this.iter = iter;
}
public boolean hasNext() {
return iter.hasNext();
}
public ImageTranscoder next() {
ImageTranscoderSpi spi = null;
spi = (ImageTranscoderSpi)iter.next();
return spi.createTranscoderInstance();
}
public void remove() {
throw new UnsupportedOperationException();
}
}
static class TranscoderFilter
implements ServiceRegistry.Filter {
String readerSpiName;
String writerSpiName;
public TranscoderFilter(ImageReaderSpi readerSpi,
ImageWriterSpi writerSpi) {
this.readerSpiName = readerSpi.getClass().getName();
this.writerSpiName = writerSpi.getClass().getName();
}
public boolean filter(Object elt) {
ImageTranscoderSpi spi = (ImageTranscoderSpi)elt;
String readerName = spi.getReaderServiceProviderName();
String writerName = spi.getWriterServiceProviderName();
return (readerName.equals(readerSpiName) &&
writerName.equals(writerSpiName));
}
}
/**
* Returns an <code>Iterator containing all currently
* registered <code>ImageTranscoders that claim to be
* able to transcode between the metadata of the given
* <code>ImageReader and ImageWriter.
*
* @param reader an <code>ImageReader.
* @param writer an <code>ImageWriter.
*
* @return an <code>Iterator containing
* <code>ImageTranscoders.
*
* @exception IllegalArgumentException if <code>reader or
* <code>writer is null.
*/
public static Iterator<ImageTranscoder>
getImageTranscoders(ImageReader reader, ImageWriter writer)
{
if (reader == null) {
throw new IllegalArgumentException("reader == null!");
}
if (writer == null) {
throw new IllegalArgumentException("writer == null!");
}
ImageReaderSpi readerSpi = reader.getOriginatingProvider();
ImageWriterSpi writerSpi = writer.getOriginatingProvider();
ServiceRegistry.Filter filter =
new TranscoderFilter(readerSpi, writerSpi);
Iterator iter;
// Ensure category is present
try {
iter = theRegistry.getServiceProviders(ImageTranscoderSpi.class,
filter, true);
} catch (IllegalArgumentException e) {
return Collections.emptyIterator();
}
return new ImageTranscoderIterator(iter);
}
// All-in-one methods
/**
* Returns a <code>BufferedImage as the result of decoding
* a supplied <code>File with an ImageReader
* chosen automatically from among those currently registered.
* The <code>File is wrapped in an
* <code>ImageInputStream. If no registered
* <code>ImageReader claims to be able to read the
* resulting stream, <code>null is returned.
*
* <p> The current cache settings from getUseCacheand
* <code>getCacheDirectory will be used to control caching in the
* <code>ImageInputStream that is created.
*
* <p> Note that there is no read method that takes a
* filename as a <code>String; use this method instead after
* creating a <code>File from the filename.
*
* <p> This method does not attempt to locate
* <code>ImageReaders that can read directly from a
* <code>File; that may be accomplished using
* <code>IIORegistry and ImageReaderSpi.
*
* @param input a <code>File to read from.
*
* @return a <code>BufferedImage containing the decoded
* contents of the input, or <code>null.
*
* @exception IllegalArgumentException if <code>input is
* <code>null.
* @exception IOException if an error occurs during reading.
*/
public static BufferedImage read(File input) throws IOException {
if (input == null) {
throw new IllegalArgumentException("input == null!");
}
if (!input.canRead()) {
throw new IIOException("Can't read input file!");
}
ImageInputStream stream = createImageInputStream(input);
if (stream == null) {
throw new IIOException("Can't create an ImageInputStream!");
}
BufferedImage bi = read(stream);
if (bi == null) {
stream.close();
}
return bi;
}
/**
* Returns a <code>BufferedImage as the result of decoding
* a supplied <code>InputStream with an ImageReader
* chosen automatically from among those currently registered.
* The <code>InputStream is wrapped in an
* <code>ImageInputStream. If no registered
* <code>ImageReader claims to be able to read the
* resulting stream, <code>null is returned.
*
* <p> The current cache settings from getUseCacheand
* <code>getCacheDirectory will be used to control caching in the
* <code>ImageInputStream that is created.
*
* <p> This method does not attempt to locate
* <code>ImageReaders that can read directly from an
* <code>InputStream; that may be accomplished using
* <code>IIORegistry and ImageReaderSpi.
*
* <p> This method does not close the provided
* <code>InputStream after the read operation has completed;
* it is the responsibility of the caller to close the stream, if desired.
*
* @param input an <code>InputStream to read from.
*
* @return a <code>BufferedImage containing the decoded
* contents of the input, or <code>null.
*
* @exception IllegalArgumentException if <code>input is
* <code>null.
* @exception IOException if an error occurs during reading.
*/
public static BufferedImage read(InputStream input) throws IOException {
if (input == null) {
throw new IllegalArgumentException("input == null!");
}
ImageInputStream stream = createImageInputStream(input);
BufferedImage bi = read(stream);
if (bi == null) {
stream.close();
}
return bi;
}
/**
* Returns a <code>BufferedImage as the result of decoding
* a supplied <code>URL with an ImageReader
* chosen automatically from among those currently registered. An
* <code>InputStream is obtained from the URL,
* which is wrapped in an <code>ImageInputStream. If no
* registered <code>ImageReader claims to be able to read
* the resulting stream, <code>null is returned.
*
* <p> The current cache settings from getUseCacheand
* <code>getCacheDirectory will be used to control caching in the
* <code>ImageInputStream that is created.
*
* <p> This method does not attempt to locate
* <code>ImageReaders that can read directly from a
* <code>URL; that may be accomplished using
* <code>IIORegistry and ImageReaderSpi.
*
* @param input a <code>URL to read from.
*
* @return a <code>BufferedImage containing the decoded
* contents of the input, or <code>null.
*
* @exception IllegalArgumentException if <code>input is
* <code>null.
* @exception IOException if an error occurs during reading.
*/
public static BufferedImage read(URL input) throws IOException {
if (input == null) {
throw new IllegalArgumentException("input == null!");
}
InputStream istream = null;
try {
istream = input.openStream();
} catch (IOException e) {
throw new IIOException("Can't get input stream from URL!", e);
}
ImageInputStream stream = createImageInputStream(istream);
BufferedImage bi;
try {
bi = read(stream);
if (bi == null) {
stream.close();
}
} finally {
istream.close();
}
return bi;
}
/**
* Returns a <code>BufferedImage as the result of decoding
* a supplied <code>ImageInputStream with an
* <code>ImageReader chosen automatically from among those
* currently registered. If no registered
* <code>ImageReader claims to be able to read the stream,
* <code>null is returned.
*
* <p> Unlike most other methods in this class, this method does
* close the provided <code>ImageInputStream after the read
* operation has completed, unless <code>null is returned,
* in which case this method <em>does not close the stream.
*
* @param stream an <code>ImageInputStream to read from.
*
* @return a <code>BufferedImage containing the decoded
* contents of the input, or <code>null.
*
* @exception IllegalArgumentException if <code>stream is
* <code>null.
* @exception IOException if an error occurs during reading.
*/
public static BufferedImage read(ImageInputStream stream)
throws IOException {
if (stream == null) {
throw new IllegalArgumentException("stream == null!");
}
Iterator iter = getImageReaders(stream);
if (!iter.hasNext()) {
return null;
}
ImageReader reader = (ImageReader)iter.next();
ImageReadParam param = reader.getDefaultReadParam();
reader.setInput(stream, true, true);
BufferedImage bi;
try {
bi = reader.read(0, param);
} finally {
reader.dispose();
stream.close();
}
return bi;
}
/**
* Writes an image using the an arbitrary <code>ImageWriter
* that supports the given format to an
* <code>ImageOutputStream. The image is written to the
* <code>ImageOutputStream starting at the current stream
* pointer, overwriting existing stream data from that point
* forward, if present.
*
* <p> This method does not close the provided
* <code>ImageOutputStream after the write operation has completed;
* it is the responsibility of the caller to close the stream, if desired.
*
* @param im a <code>RenderedImage to be written.
* @param formatName a <code>String containing the informal
* name of the format.
* @param output an <code>ImageOutputStream to be written to.
*
* @return <code>false if no appropriate writer is found.
*
* @exception IllegalArgumentException if any parameter is
* <code>null.
* @exception IOException if an error occurs during writing.
*/
public static boolean write(RenderedImage im,
String formatName,
ImageOutputStream output) throws IOException {
if (im == null) {
throw new IllegalArgumentException("im == null!");
}
if (formatName == null) {
throw new IllegalArgumentException("formatName == null!");
}
if (output == null) {
throw new IllegalArgumentException("output == null!");
}
return doWrite(im, getWriter(im, formatName), output);
}
/**
* Writes an image using an arbitrary <code>ImageWriter
* that supports the given format to a <code>File. If
* there is already a <code>File present, its contents are
* discarded.
*
* @param im a <code>RenderedImage to be written.
* @param formatName a <code>String containing the informal
* name of the format.
* @param output a <code>File to be written to.
*
* @return <code>false if no appropriate writer is found.
*
* @exception IllegalArgumentException if any parameter is
* <code>null.
* @exception IOException if an error occurs during writing.
*/
public static boolean write(RenderedImage im,
String formatName,
File output) throws IOException {
if (output == null) {
throw new IllegalArgumentException("output == null!");
}
ImageOutputStream stream = null;
ImageWriter writer = getWriter(im, formatName);
if (writer == null) {
/* Do not make changes in the file system if we have
* no appropriate writer.
*/
return false;
}
try {
output.delete();
stream = createImageOutputStream(output);
} catch (IOException e) {
throw new IIOException("Can't create output stream!", e);
}
try {
return doWrite(im, writer, stream);
} finally {
stream.close();
}
}
/**
* Writes an image using an arbitrary <code>ImageWriter
* that supports the given format to an <code>OutputStream.
*
* <p> This method does not close the provided
* <code>OutputStream after the write operation has completed;
* it is the responsibility of the caller to close the stream, if desired.
*
* <p> The current cache settings from getUseCacheand
* <code>getCacheDirectory will be used to control caching.
*
* @param im a <code>RenderedImage to be written.
* @param formatName a <code>String containing the informal
* name of the format.
* @param output an <code>OutputStream to be written to.
*
* @return <code>false if no appropriate writer is found.
*
* @exception IllegalArgumentException if any parameter is
* <code>null.
* @exception IOException if an error occurs during writing.
*/
public static boolean write(RenderedImage im,
String formatName,
OutputStream output) throws IOException {
if (output == null) {
throw new IllegalArgumentException("output == null!");
}
ImageOutputStream stream = null;
try {
stream = createImageOutputStream(output);
} catch (IOException e) {
throw new IIOException("Can't create output stream!", e);
}
try {
return doWrite(im, getWriter(im, formatName), stream);
} finally {
stream.close();
}
}
/**
* Returns <code>ImageWriter instance according to given
* rendered image and image format or <code>null if there
* is no appropriate writer.
*/
private static ImageWriter getWriter(RenderedImage im,
String formatName) {
ImageTypeSpecifier type =
ImageTypeSpecifier.createFromRenderedImage(im);
Iterator<ImageWriter> iter = getImageWriters(type, formatName);
if (iter.hasNext()) {
return iter.next();
} else {
return null;
}
}
/**
* Writes image to output stream using given image writer.
*/
private static boolean doWrite(RenderedImage im, ImageWriter writer,
ImageOutputStream output) throws IOException {
if (writer == null) {
return false;
}
writer.setOutput(output);
try {
writer.write(im);
} finally {
writer.dispose();
output.flush();
}
return true;
}
}
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