org.apache.hadoop.fs.FsUrlStreamHandlerFactory Maven / Gradle / Ivy
/**
* 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.hadoop.fs;
import java.io.IOException;
import java.net.URLStreamHandlerFactory;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
/**
* Factory for URL stream handlers.
*
* There is only one handler whose job is to create UrlConnections. A
* FsUrlConnection relies on FileSystem to choose the appropriate FS
* implementation.
*
* Before returning our handler, we make sure that FileSystem knows an
* implementation for the requested scheme/protocol.
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class FsUrlStreamHandlerFactory implements
URLStreamHandlerFactory {
private static final Logger LOG =
LoggerFactory.getLogger(FsUrlStreamHandlerFactory.class);
/**
* These are the protocols with MUST NOT be exported, as doing so
* would conflict with the standard URL handlers registered by
* the JVM. Many things will break.
*/
public static final String[] UNEXPORTED_PROTOCOLS = {
"http", "https"
};
// The configuration holds supported FS implementation class names.
private Configuration conf;
// This map stores whether a protocol is know or not by FileSystem
private Map protocols =
new ConcurrentHashMap();
// The URL Stream handler
private java.net.URLStreamHandler handler;
public FsUrlStreamHandlerFactory() {
this(new Configuration());
}
public FsUrlStreamHandlerFactory(Configuration conf) {
this.conf = new Configuration(conf);
// force init of FileSystem code to avoid HADOOP-9041
try {
FileSystem.getFileSystemClass("file", conf);
} catch (IOException io) {
throw new RuntimeException(io);
}
this.handler = new FsUrlStreamHandler(this.conf);
for (String protocol : UNEXPORTED_PROTOCOLS) {
protocols.put(protocol, false);
}
}
@Override
public java.net.URLStreamHandler createURLStreamHandler(String protocol) {
LOG.debug("Creating handler for protocol {}", protocol);
if (!protocols.containsKey(protocol)) {
boolean known = true;
try {
Class impl
= FileSystem.getFileSystemClass(protocol, conf);
LOG.debug("Found implementation of {}: {}", protocol, impl);
}
catch (IOException ex) {
known = false;
}
protocols.put(protocol, known);
}
if (protocols.get(protocol)) {
LOG.debug("Using handler for protocol {}", protocol);
return handler;
} else {
// FileSystem does not know the protocol, let the VM handle this
LOG.debug("Unknown protocol {}, delegating to default implementation",
protocol);
return null;
}
}
}