library/src/main/java/com/qiniu/android/dns/DnsManager.java
public DnsManager putHosts(String domain, String ip) {
        hosts.put(domain, ip);
        return this;
    }
public DnsManager putHosts(String domain, String ip) {
        hosts.put(domain, ip);
        return this;
    }
插入指定运营商的hosts配置

@param domain 域名
@param ip     ip
@return 当前的DnsManager，便于链式调用