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A small collection of utility classes
package info.freelibrary.util;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Paths;
import java.util.Enumeration;
import java.util.LinkedList;
import java.util.List;
import java.util.StringTokenizer;
import java.util.jar.Attributes;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.jar.Manifest;
import info.freelibrary.util.warnings.PMD;
/**
* A small collection of Jar file utilities.
*/
public final class JarUtils {
/**
* The delimiter between the Jar file and its path.
*/
public static final String JAR_URL_DELIMITER = "!/";
/**
* A constant for the protocol of a Jar file.
*/
public static final String JAR_URL_PROTOCOL = "jar:file://";
/**
* The logger used by the Jar utilities.
*/
private static final Logger LOGGER = LoggerFactory.getLogger(JarUtils.class, MessageCodes.BUNDLE);
/**
* The number of components in a Jar URL.
*/
private static final int URL_COMPONENT_COUNT = 2;
/**
* Creates a new Jar utilities instance.
*/
private JarUtils() {
// This is intentionally left empty
}
/**
* Tests whether the supplied file path exists in the supplied Jar file. This method does not close the JarFile.
*
* @param aJarFile A jar file to search
* @param aFilePath A path for which to search
* @return True if the file path is found; else, false
* @throws IOException If the jar file cannot be read
*/
public static boolean contains(final JarFile aJarFile, final String aFilePath) throws IOException {
final Enumeration entries = aJarFile.entries();
while (entries.hasMoreElements()) {
if (entries.nextElement().getName().equals(aFilePath)) {
return true;
}
}
return false;
}
/**
* Extract the supplied path from the supplied Jar file to the supplied {@link java.io.File} location. This method
* closes the JarFile.
*
* @param aJarFile A Jar file from which to extract
* @param aFilePath The Jar's file path of the file to extract
* @param aDestDir The destination directory into which the file should be extracted
* @throws IOException If there is an exception thrown while reading or writing the file
* @throws NoSuchFileException If the Jar file cannot be found at the supplied path
*/
public static void extract(final File aJarFile, final String aFilePath, final File aDestDir) throws IOException {
extract(new JarFile(aJarFile), aFilePath, aDestDir);
}
/**
* Extract a particular path from the supplied Jar file to a supplied {@link java.io.File} location. This method
* closes the JarFile.
*
* @param aJarFile A Jar file from which to extract the supplied file path
* @param aFilePath The Jar's file path of the file to extract
* @param aDestDir The destination directory into which the file should be extracted
* @throws IOException If there is an exception thrown while reading or writing the file
* @throws NoSuchFileException If the Jar file cannot be found at the supplied path
*/
public static void extract(final JarFile aJarFile, final String aFilePath, final File aDestDir) throws IOException {
try (aJarFile) {
final Enumeration entries = aJarFile.entries();
while (entries.hasMoreElements()) {
final JarEntry entry = entries.nextElement();
final String entryName = entry.getName();
final File file = new File(aDestDir + File.separator + entryName);
if (entryName.equals(aFilePath)) {
final File parent = file.getParentFile();
if (!parent.exists() && !parent.mkdirs()) {
throw new IOException(LOGGER.getI18n(MessageCodes.UTIL_038, file));
}
try (InputStream inputStream = aJarFile.getInputStream(entry);
OutputStream outputStream = Files.newOutputStream(Paths.get(file.getAbsolutePath()))) {
IOUtils.copyStream(inputStream, outputStream);
}
}
}
} // Close JarFile when done with it
}
/**
* Extract the supplied path from the supplied Jar file to a supplied {@link java.io.File} location. This method
* closes the JarFile.
*
* @param aJarFilePath The path to a Jar file from which to extract
* @param aFilePath The Jar's file path of the file to extract
* @param aDestDir The destination directory into which the file should be extracted
* @throws IOException If there is an exception thrown while reading or writing the file
* @throws NoSuchFileException If the Jar file cannot be found at the supplied path
*/
public static void extract(final String aJarFilePath, final String aFilePath, final File aDestDir)
throws IOException {
if (aJarFilePath.startsWith(JAR_URL_PROTOCOL)) {
extract(URI.create(aJarFilePath + JAR_URL_DELIMITER + aFilePath).toURL(), aDestDir);
} else {
extract(new File(aJarFilePath), aFilePath, aDestDir);
}
}
/**
* Extracts the supplied path from the supplied Jar file's URL to the supplied {@link java.io.File} location. This
* method closes the JarFile.
*
* @param aJarURL A Jar URL that contains the system file path of a Jar file and a subfile path
* @param aDestDir The destination directory into which the file should be extracted
* @throws IOException If there is an exception thrown while reading or writing the file
* @throws NoSuchFileException If the Jar file cannot be found at the supplied path
* @throws MalformedUrlException If the supplied URL does not also contain a subfile path
*/
public static void extract(final URL aJarURL, final File aDestDir) throws IOException {
final String[] jarURLParts = aJarURL.getFile().split(JAR_URL_DELIMITER);
final File jarFile;
if (jarURLParts.length != URL_COMPONENT_COUNT) {
throw new MalformedUrlException(LOGGER.getMessage(MessageCodes.UTIL_072, aJarURL));
}
jarFile = new File(jarURLParts[0].substring(aJarURL.getProtocol().length() + 4)); // Remove protocol
extract(jarFile, jarURLParts[1], aDestDir);
}
/**
* Gets a list of jar files in the classpath (this includes jars in jars, one level deep).
*
* @return An array of {@link URL}s found in the classpath
* @throws IOException If there is trouble reading the classpath
*/
@SuppressWarnings({ PMD.AVOID_DEEPLY_NESTED_IF_STMTS, PMD.COGNITIVE_COMPLEXITY })
public static URL[] getJarURLs() throws IOException {
final List urlList = new LinkedList<>();
for (final JarFile jarFile : ClasspathUtils.getJarFiles()) {
try (jarFile) {
final Manifest manifest = jarFile.getManifest();
final URL jarURL = URI.create(JAR_URL_PROTOCOL + jarFile.getName() + JAR_URL_DELIMITER).toURL();
urlList.add(jarURL);
if (manifest != null) {
final Attributes attributes = manifest.getMainAttributes();
if (attributes != null) {
final String classpath = attributes.getValue("Class-Path");
if (classpath != null) {
final StringTokenizer tokenizer = new StringTokenizer(classpath);
while (tokenizer.hasMoreTokens()) {
final String jarPath = tokenizer.nextToken();
if (jarPath.endsWith(".jar")) {
urlList.add(URI.create(jarURL.toExternalForm() + jarPath).toURL());
}
}
}
}
}
}
}
return urlList.toArray(new URL[0]);
}
}
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