InetAddressImpl.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * particular file as subject to the "Classpath" exception as provided
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package java.net;

import java.io.IOException;

/**
 * Package private interface to "implementation" used by {@link InetAddress}.
 *
 * See {@link java.net.Inet4AddressImpl} and {@link java.net.Inet6AddressImpl}.
 *
 * @since 1.4
 */
// InetAddress类的一些补充，主要用来映射主机地址/名称，以及判断网络地址的可用性
interface InetAddressImpl {
    
    // 本地主机名称
    String getLocalHostName() throws UnknownHostException;
    
    // 本地环回地址
    InetAddress loopbackAddress();
    
    // 通配符地址（特殊地址，字节全为0）
    InetAddress anyLocalAddress();
    
    // 通过指定的网络接口判断给定的网络地址是否可用，ttl代表网络跳数
    boolean isReachable(InetAddress addr, int timeout, NetworkInterface netif, int ttl) throws IOException;
    
    // 将主机名称或主机地址映射为InetAddress实例
    InetAddress[] lookupAllHostAddr(String hostname) throws UnknownHostException;
    
    // 根据主机地址查找映射的主机名称
    String getHostByAddr(byte[] addr) throws UnknownHostException;
    
}