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Java example source code file (AbstractDnsRecord.java)

This example Java source code file (AbstractDnsRecord.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractdnsrecord, class_in, dnsrecord, dnsrecordtype, illegalargumentexception, net, network, override, string, stringbuilder, unstableapi

The AbstractDnsRecord.java Java example source code

/*
 * Copyright 2015 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.handler.codec.dns;

import io.netty.util.internal.StringUtil;
import io.netty.util.internal.UnstableApi;

import java.net.IDN;

import static io.netty.util.internal.ObjectUtil.checkNotNull;

/**
 * A skeletal implementation of {@link DnsRecord}.
 */
@UnstableApi
public abstract class AbstractDnsRecord implements DnsRecord {

    private final String name;
    private final DnsRecordType type;
    private final short dnsClass;
    private final long timeToLive;
    private int hashCode;

    /**
     * Creates a new {@link #CLASS_IN IN-class} record.
     *
     * @param name the domain name
     * @param type the type of the record
     * @param timeToLive the TTL value of the record
     */
    protected AbstractDnsRecord(String name, DnsRecordType type, long timeToLive) {
        this(name, type, CLASS_IN, timeToLive);
    }

    /**
     * Creates a new record.
     *
     * @param name the domain name
     * @param type the type of the record
     * @param dnsClass the class of the record, usually one of the following:
     *                 <ul>
     *                     <li>{@link #CLASS_IN}
     *                     <li>{@link #CLASS_CSNET}
     *                     <li>{@link #CLASS_CHAOS}
     *                     <li>{@link #CLASS_HESIOD}
     *                     <li>{@link #CLASS_NONE}
     *                     <li>{@link #CLASS_ANY}
     *                 </ul>
     * @param timeToLive the TTL value of the record
     */
    protected AbstractDnsRecord(String name, DnsRecordType type, int dnsClass, long timeToLive) {
        if (timeToLive < 0) {
            throw new IllegalArgumentException("timeToLive: " + timeToLive + " (expected: >= 0)");
        }
        // Convert to ASCII which will also check that the length is not too big.
        // See:
        //   - https://github.com/netty/netty/issues/4937
        //   - https://github.com/netty/netty/issues/4935
        this.name = appendTrailingDot(IDN.toASCII(checkNotNull(name, "name")));
        this.type = checkNotNull(type, "type");
        this.dnsClass = (short) dnsClass;
        this.timeToLive = timeToLive;
    }

    private static String appendTrailingDot(String name) {
        if (name.length() > 0 && name.charAt(name.length() - 1) != '.') {
            return name + '.';
        }
        return name;
    }

    @Override
    public String name() {
        return name;
    }

    @Override
    public DnsRecordType type() {
        return type;
    }

    @Override
    public int dnsClass() {
        return dnsClass & 0xFFFF;
    }

    @Override
    public long timeToLive() {
        return timeToLive;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }

        if (!(obj instanceof DnsRecord)) {
            return false;
        }

        final DnsRecord that = (DnsRecord) obj;
        final int hashCode = this.hashCode;
        if (hashCode != 0 && hashCode != that.hashCode()) {
            return false;
        }

        return type().intValue() == that.type().intValue() &&
               dnsClass() == that.dnsClass() &&
               name().equals(that.name());
    }

    @Override
    public int hashCode() {
        final int hashCode = this.hashCode;
        if (hashCode != 0) {
            return hashCode;
        }

        return this.hashCode = name.hashCode() * 31 + type().intValue() * 31 + dnsClass();
    }

    @Override
    public String toString() {
        StringBuilder buf = new StringBuilder(64);

        buf.append(StringUtil.simpleClassName(this))
           .append('(')
           .append(name())
           .append(' ')
           .append(timeToLive())
           .append(' ');

        DnsMessageUtil.appendRecordClass(buf, dnsClass())
                      .append(' ')
                      .append(type().name())
                      .append(')');

        return buf.toString();
    }
}

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