设置OkHttp的DNS域名解析

Android

使用OkHttp的Dns可以自由配置想要的Dns解析，可以用来在不同环境下指定Host的指向。
也可以定向解析一些IP，可以加速网络请求。

/**
 * 预置DNS解析,默认使用系统的{@link Dns#SYSTEM}
 */
public class DnsFactory {
    public static Dns getDns() {
        switch (Environment.getType()) {
            case Environment.TYPE_TEST:
                return new DevDns();
            case Environment.TYPE_PRE_RELEASE:
                return new PreReleaseDns();
            case Environment.TYPE_ONLINE:
            default:
                return Dns.SYSTEM;
        }
    }
    // 日常测试环境DNS
    private static class DevDns implements Dns {
        @Override
        public List<InetAddress> lookup(String hostname) throws UnknownHostException {
            return SYSTEM.lookup(hostname);
        }
    }
    // 预发环境DNS
    private static class PreReleaseDns implements Dns {
        @Override
        public List<InetAddress> lookup(String hostname) throws UnknownHostException {
            // hostname ip 配置白名单，手动设置Host对应的IP
            if ("xxxx".equals(hostname)
                    || "xxxx".equals(hostname)
                    || "xxxx".equals(hostname)
                    || "xxxx".equals(hostname)) {
                InetAddress byAddress = InetAddress.getByAddress(hostname, new byte[]{xx,xx,xx,xx});
                return Collections.singletonList(byAddress);
            } else {
                return SYSTEM.lookup(hostname);
            }
        }
    }
}

在OkHttpClient全局配置时设置上Dns解析器

OkHttpClient.Builder builder = new OkHttpClient.Builder()
                .connectTimeout(20, TimeUnit.SECONDS)
                .readTimeout(30, TimeUnit.SECONDS)
                .writeTimeout(30, TimeUnit.SECONDS)
                // 根据具体开发环境设置DNS解析器
                builder.dns(DnsFactory.getDns());