SpringCloud组件 & 源码剖析：Eureka服务注册方式流程全面分析

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public class EurekaClientAutoConfiguration {
    //省略部分源码
    @Bean
    @ConditionalOnMissingBean(value = EurekaInstanceConfig.class, search        = SearchStrategy.CURRENT)
    public EurekaInstanceConfigBean eurekaInstanceConfigBean(InetUtils inetUtils,                                                       ManagementMetadataProvider managementMetadataProvider) {
      //省略部分源码
      // 传递
      EurekaInstanceConfigBean instance = new EurekaInstanceConfigBean(inetUtils);
      // 省略部分源码
    }
    //省略部分源码
}

// 通过有参构造函数实例化EurekaInstanceConfigBean配置实体
EurekaInstanceConfigBean instance = new EurekaInstanceConfigBean(inetUtils);

public EurekaInstanceConfigBean(InetUtils inetUtils) {
    this.inetUtils = inetUtils;
    this.hostInfo = this.inetUtils.findFirstNonLoopbackHostInfo();
    this.ipAddress = this.hostInfo.getIpAddress();
    this.hostname = this.hostInfo.getHostname();
}

public HostInfo findFirstNonLoopbackHostInfo() {
    InetAddress address = findFirstNonLoopbackAddress();
    if (address != null) {
        return convertAddress(address);
    }
    HostInfo hostInfo = new HostInfo();
    hostInfo.setHostname(this.properties.getDefaultHostname());
    hostInfo.setIpAddress(this.properties.getDefaultIpAddress());
    return hostInfo;
}

public InetAddress findFirstNonLoopbackAddress() {
    InetAddress result = null;
    try {
        int lowest = Integer.MAX_VALUE;
        for (Enumeration<NetworkInterface> nics = NetworkInterface
                .getNetworkInterfaces(); nics.hasMoreElements();) {
            NetworkInterface ifc = nics.nextElement();
            if (ifc.isUp()) {
                log.trace("Testing interface: " + ifc.getDisplayName());
                if (ifc.getIndex() < lowest || result == null) {
                    lowest = ifc.getIndex();
                }
                else if (result != null) {
                    continue;
                }

                // @formatter:off
                if (!ignoreInterface(ifc.getDisplayName())) {
                    for (Enumeration<InetAddress> addrs = ifc
                            .getInetAddresses(); addrs.hasMoreElements();) {
                        InetAddress address = addrs.nextElement();
                        if (address instanceof Inet4Address
                                && !address.isLoopbackAddress()
                                && isPreferredAddress(address)) {
                            log.trace("Found non-loopback interface: "
                                    + ifc.getDisplayName());
                            result = address;
                        }
                    }
                }
                // @formatter:on
            }
        }
    }
    catch (IOException ex) {
        log.error("Cannot get first non-loopback address", ex);
    }

    if (result != null) {
        return result;
    }

    try {
        return InetAddress.getLocalHost();
    }
    catch (UnknownHostException e) {
        log.warn("Unable to retrieve localhost");
    }

    return null;
}

public class InetUtilsProperties {
    public static final String PREFIX = "spring.cloud.inetutils";

    /**
     * The default hostname. Used in case of errors.
     */
    private String defaultHostname = "localhost";

    /**
     * The default ipaddress. Used in case of errors.
     */
    private String defaultIpAddress = "127.0.0.1";
}

@Override
public String getHostName(boolean refresh) {
    if (refresh && !this.hostInfo.override) {
        this.ipAddress = this.hostInfo.getIpAddress();
        this.hostname = this.hostInfo.getHostname();
    }
    return this.preferIpAddress ? this.ipAddress : this.hostname;
}

return this.preferIpAddress ? this.ipAddress : this.hostname;