netty5/resolver-dns/src/main/java/io/netty/resolver/dns/NameServerComparator.java
田欧 e8efcd82a8 migrate java8: use requireNonNull (#8840)
Motivation:

We can just use Objects.requireNonNull(...) as a replacement for ObjectUtil.checkNotNull(....)

Modifications:

- Use Objects.requireNonNull(...)

Result:

Less code to maintain.
2019-02-04 10:32:25 +01:00

62 lines
2.4 KiB
Java

/*
* Copyright 2018 The Netty Project
*
* The Netty Project 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 io.netty.resolver.dns;
import static java.util.Objects.requireNonNull;
import java.io.Serializable;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.util.Comparator;
import java.util.List;
/**
* Special {@link Comparator} implementation to sort the nameservers to use when follow redirects.
*
* This implementation follows all the semantics listed in the
* <a href="https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html">Comparator apidocs</a>
* with the limitation that {@link InetSocketAddress#equals(Object)} will not result in the same return value as
* {@link #compare(InetSocketAddress, InetSocketAddress)}. This is completely fine as this should only be used
* to sort {@link List}s.
*/
public final class NameServerComparator implements Comparator<InetSocketAddress>, Serializable {
private static final long serialVersionUID = 8372151874317596185L;
private final Class<? extends InetAddress> preferredAddressType;
public NameServerComparator(Class<? extends InetAddress> preferredAddressType) {
this.preferredAddressType = requireNonNull(preferredAddressType, "preferredAddressType");
}
@Override
public int compare(InetSocketAddress addr1, InetSocketAddress addr2) {
if (addr1.equals(addr2)) {
return 0;
}
if (!addr1.isUnresolved() && !addr2.isUnresolved()) {
if (addr1.getAddress().getClass() == addr2.getAddress().getClass()) {
return 0;
}
return preferredAddressType.isAssignableFrom(addr1.getAddress().getClass()) ? -1 : 1;
}
if (addr1.isUnresolved() && addr2.isUnresolved()) {
return 0;
}
return addr1.isUnresolved() ? 1 : -1;
}
}