OkHttp设置超时时间

在使用okHttp的时候我们经常会使用超时设置：如下：

okHttpClient = new OkHttpClient.Builder()
                .connectTimeout(5, TimeUnit.SECONDS)
                .writeTimeout(5, TimeUnit.SECONDS)
                .readTimeout(5, TimeUnit.SECONDS)
                .dns(new xDns(5))
                .build();      

但是在某些情况下，eg：域名解析不了。我们设置的这些超时值不管用，往往需要几十秒之后get/post之后才返回错误。所以此时我们就需要设置一下dns解析超时，关于okhttp的dns解析超时网上很多方法，这里我使用最简答的：okhttp.dns接口：

public class xDns implements Dns {
    private long timeout  = 5;

    public xDns(long timeout){
        this.timeout = timeout;
    }

    @Override
    public List<InetAddress> lookup(String hostname) throws UnknownHostException {
        if(hostname == null){
            throw new UnknownHostException("host name is null");
        }
        else{
            try {
                FutureTask<List<InetAddress>> task = new FutureTask<>(
                        new Callable<List<InetAddress>>() {
                            @Override
                            public List<InetAddress> call() throws Exception {
                                return Arrays.asList(InetAddress.getAllByName(hostname));
                            }
                        });
                new Thread(task).start();
                return task.get(timeout, TimeUnit.SECONDS);
            } catch (Exception var4) {
                UnknownHostException unknownHostException =
                        new UnknownHostException("Unable to resolve host " + hostname);
                unknownHostException.initCause(var4);
                throw unknownHostException;
            }
        }
    }
}