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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.analysis.util;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.util.Objects;
import org.apache.lucene.util.ClasspathResourceLoader;
import org.apache.lucene.util.ModuleResourceLoader;
import org.apache.lucene.util.ResourceLoader;
/**
* Simple {@link ResourceLoader} that opens resource files from the local file system, optionally
* resolving against a base directory.
*
* This loader wraps a delegate {@link ResourceLoader} that is used to resolve all files, the
* current base directory does not contain. {@link #newInstance} is always resolved against the
* delegate, as a {@link ClassLoader} is needed.
*
*
You can chain several {@code FilesystemResourceLoader}s to allow lookup of files in more than
* one base directory.
*/
public final class FilesystemResourceLoader implements ResourceLoader {
private final Path baseDirectory;
private final ResourceLoader delegate;
/**
* Creates a resource loader that resolves resources against the given base directory. Files not
* found in file system and class lookups are delegated to {@link ClassLoader}.
*
*
To use this constructor with the Java Module System, you must open all modules that contain
* resources to the {@code org.apache.lucene.core} module, otherwise resources can't be looked up.
* It is recommended to use {@link #FilesystemResourceLoader(Path, Module)} for such use cases as
* this would limit to certain modules.
*/
public FilesystemResourceLoader(Path baseDirectory, ClassLoader delegate) {
this(baseDirectory, new ClasspathResourceLoader(delegate));
}
/**
* Creates a resource loader that resolves resources against the given base directory. Files not
* found in file system and class lookups are delegated to {@link ModuleResourceLoader}.
*
*
To use this constructor, you must open the module to the {@code org.apache.lucene.core}
* module, otherwise resources can't be looked up.
*/
public FilesystemResourceLoader(Path baseDirectory, Module delegate) {
this(baseDirectory, new ModuleResourceLoader(delegate));
}
/**
* Creates a resource loader that resolves resources against the given base directory. Files not
* found in file system and class lookups are delegated to the given delegate {@link
* ResourceLoader}.
*/
public FilesystemResourceLoader(Path baseDirectory, ResourceLoader delegate) {
if (!Files.isDirectory(Objects.requireNonNull(baseDirectory)))
throw new IllegalArgumentException(baseDirectory + " is not a directory");
if (delegate == null)
throw new IllegalArgumentException("delegate ResourceLoader may not be null");
this.baseDirectory = baseDirectory;
this.delegate = delegate;
}
@Override
public InputStream openResource(String resource) throws IOException {
try {
return Files.newInputStream(baseDirectory.resolve(resource));
} catch (@SuppressWarnings("unused") FileNotFoundException | NoSuchFileException fnfe) {
return delegate.openResource(resource);
}
}
@Override
public T newInstance(String cname, Class expectedType) {
return delegate.newInstance(cname, expectedType);
}
@Override
public Class findClass(String cname, Class expectedType) {
return delegate.findClass(cname, expectedType);
}
}