org.apache.lucene.analysis.util.ClasspathResourceLoader Maven / Gradle / Ivy
package org.apache.lucene.analysis.util;
/*
* 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.
*/
import java.io.IOException;
import java.io.InputStream;
/**
* Simple {@link ResourceLoader} that uses {@link ClassLoader#getResourceAsStream(String)}
* and {@link Class#forName(String,boolean,ClassLoader)} to open resources and
* classes, respectively.
*/
public final class ClasspathResourceLoader implements ResourceLoader {
private final Class clazz;
private final ClassLoader loader;
/**
* Creates an instance using the context classloader to load Resources and classes.
* Resource paths must be absolute.
*/
public ClasspathResourceLoader() {
this(Thread.currentThread().getContextClassLoader());
}
/**
* Creates an instance using the given classloader to load Resources and classes.
* Resource paths must be absolute.
*/
public ClasspathResourceLoader(ClassLoader loader) {
this(null, loader);
}
/**
* Creates an instance using the context classloader to load Resources and classes
* Resources are resolved relative to the given class, if path is not absolute.
*/
public ClasspathResourceLoader(Class clazz) {
this(clazz, clazz.getClassLoader());
}
private ClasspathResourceLoader(Class clazz, ClassLoader loader) {
this.clazz = clazz;
this.loader = loader;
}
@Override
public InputStream openResource(String resource) throws IOException {
final InputStream stream = (clazz != null) ?
clazz.getResourceAsStream(resource) :
loader.getResourceAsStream(resource);
if (stream == null)
throw new IOException("Resource not found: " + resource);
return stream;
}
@Override
public Class findClass(String cname, Class expectedType) {
try {
return Class.forName(cname, true, loader).asSubclass(expectedType);
} catch (Exception e) {
throw new RuntimeException("Cannot load class: " + cname, e);
}
}
@Override
public T newInstance(String cname, Class expectedType) {
Class clazz = findClass(cname, expectedType);
try {
return clazz.newInstance();
} catch (Exception e) {
throw new RuntimeException("Cannot create instance: " + cname, e);
}
}
}