Ich weiß, dass diese Frage schon ziemlich alt ist, aber nachdem ich einige Antworten ausprobiert hatte, die nicht funktionierten, und andere, die eine ganze Bibliothek für nur eine Methode erforderten, beschloss ich, eine Klasse zusammenzustellen. Sie benötigt keine Bibliotheken von Drittanbietern und wurde mit Java 8 getestet. Es gibt vier öffentliche Methoden: copyResourcesToTempDir , copyResourcesToDir , copyResourceDirectory y jar .
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.nio.file.Files;
import java.util.Enumeration;
import java.util.Optional;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
/**
* A helper to copy resources from a JAR file into a directory.
*/
public final class ResourceCopy {
/**
* URI prefix for JAR files.
*/
private static final String JAR_URI_PREFIX = "jar:file:";
/**
* The default buffer size.
*/
private static final int BUFFER_SIZE = 8 * 1024;
/**
* Copies a set of resources into a temporal directory, optionally preserving
* the paths of the resources.
* @param preserve Whether the files should be placed directly in the
* directory or the source path should be kept
* @param paths The paths to the resources
* @return The temporal directory
* @throws IOException If there is an I/O error
*/
public File copyResourcesToTempDir(final boolean preserve,
final String... paths)
throws IOException {
final File parent = new File(System.getProperty("java.io.tmpdir"));
File directory;
do {
directory = new File(parent, String.valueOf(System.nanoTime()));
} while (!directory.mkdir());
return this.copyResourcesToDir(directory, preserve, paths);
}
/**
* Copies a set of resources into a directory, preserving the paths
* and names of the resources.
* @param directory The target directory
* @param preserve Whether the files should be placed directly in the
* directory or the source path should be kept
* @param paths The paths to the resources
* @return The temporal directory
* @throws IOException If there is an I/O error
*/
public File copyResourcesToDir(final File directory, final boolean preserve,
final String... paths) throws IOException {
for (final String path : paths) {
final File target;
if (preserve) {
target = new File(directory, path);
target.getParentFile().mkdirs();
} else {
target = new File(directory, new File(path).getName());
}
this.writeToFile(
Thread.currentThread()
.getContextClassLoader()
.getResourceAsStream(path),
target
);
}
return directory;
}
/**
* Copies a resource directory from inside a JAR file to a target directory.
* @param source The JAR file
* @param path The path to the directory inside the JAR file
* @param target The target directory
* @throws IOException If there is an I/O error
*/
public void copyResourceDirectory(final JarFile source, final String path,
final File target) throws IOException {
final Enumeration<JarEntry> entries = source.entries();
final String newpath = String.format("%s/", path);
while (entries.hasMoreElements()) {
final JarEntry entry = entries.nextElement();
if (entry.getName().startsWith(newpath) && !entry.isDirectory()) {
final File dest =
new File(target, entry.getName().substring(newpath.length()));
final File parent = dest.getParentFile();
if (parent != null) {
parent.mkdirs();
}
this.writeToFile(source.getInputStream(entry), dest);
}
}
}
/**
* The JAR file containing the given class.
* @param clazz The class
* @return The JAR file or null
* @throws IOException If there is an I/O error
*/
public Optional<JarFile> jar(final Class<?> clazz) throws IOException {
final String path =
String.format("/%s.class", clazz.getName().replace('.', '/'));
final URL url = clazz.getResource(path);
Optional<JarFile> optional = Optional.empty();
if (url != null) {
final String jar = url.toString();
final int bang = jar.indexOf('!');
if (jar.startsWith(ResourceCopy.JAR_URI_PREFIX) && bang != -1) {
optional = Optional.of(
new JarFile(
jar.substring(ResourceCopy.JAR_URI_PREFIX.length(), bang)
)
);
}
}
return optional;
}
/**
* Writes an input stream to a file.
* @param input The input stream
* @param target The target file
* @throws IOException If there is an I/O error
*/
private void writeToFile(final InputStream input, final File target)
throws IOException {
final OutputStream output = Files.newOutputStream(target.toPath());
final byte[] buffer = new byte[ResourceCopy.BUFFER_SIZE];
int length = input.read(buffer);
while (length > 0) {
output.write(buffer, 0, length);
length = input.read(buffer);
}
input.close();
output.close();
}
}
