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/*
* Copyright 2015 Google Inc.
*
* Licensed 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 com.google.common.jimfs;
import static com.google.common.base.Preconditions.checkArgument;
import java.io.IOException;
import java.net.InetAddress;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
/**
* {@link URLStreamHandler} implementation for jimfs. Named {@code Handler} so that the class can be
* found by Java as described in the documentation for {@link URL#URL(String, String, int, String)
* URL}.
*
* <p>This class is only public because it is necessary for Java to find it. It is not intended to
* be used directly.
*
* @author Colin Decker
* @since 1.1
*/
public final class Handler extends URLStreamHandler {
private static final String JAVA_PROTOCOL_HANDLER_PACKAGES = "java.protocol.handler.pkgs";
/**
* Registers this handler by adding the package {@code com.google.common} to the system property
* {@code "java.protocol.handler.pkgs"}. Java will then look for this class in the {@code jimfs}
* (the name of the protocol) package of {@code com.google.common}.
*
* @throws SecurityException if the system property that needs to be set to register this handler
* can't be read or written.
*/
static void register() {
register(Handler.class);
}
/** Generic method that would allow registration of any properly placed {@code Handler} class. */
static void register(Class<? extends URLStreamHandler> handlerClass) {
checkArgument("Handler".equals(handlerClass.getSimpleName()));
String pkg = handlerClass.getPackage().getName();
int lastDot = pkg.lastIndexOf('.');
checkArgument(lastDot > 0, "package for Handler (%s) must have a parent package", pkg);
String parentPackage = pkg.substring(0, lastDot);
String packages = System.getProperty(JAVA_PROTOCOL_HANDLER_PACKAGES);
if (packages == null) {
packages = parentPackage;
} else {
packages += "|" + parentPackage;
}
System.setProperty(JAVA_PROTOCOL_HANDLER_PACKAGES, packages);
}
/** @deprecated Not intended to be called directly; this class is only for use by Java itself. */
@Deprecated
public Handler() {} // a public, no-arg constructor is required
@Override
protected URLConnection openConnection(URL url) throws IOException {
return new PathURLConnection(url);
}
@Override
@SuppressWarnings("UnsynchronizedOverridesSynchronized") // no need to synchronize to return null
protected InetAddress getHostAddress(URL url) {
// jimfs uses the URI host to specify the name of the file system being used.
// In the default implementation of getHostAddress(URL), a non-null host would cause an attempt
// to look up the IP address, causing a slowdown on calling equals/hashCode methods on the URL
// object. By returning null, we speed up equality checks on URL's (since there isn't an IP to
// connect to).
return null;
}
}
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