setDefaultHostnameVerifier中验证方法的用途

你能告诉我下面的代码是什么吗?从哪里获取主机名?verify方法的目的是什么?

static {
    //for localhost testing only
    javax.net.ssl.HttpsURLConnection.setDefaultHostnameVerifier(
            new javax.net.ssl.HostnameVerifier(){

                public boolean verify(String hostname,
                                      javax.net.ssl.SSLSession sslSession) {
                    System.out.println(" hostname = " + hostname);
                    if (hostname.equals("localhost")) {
                        return true;
                    }
                    return false;
                }
            });
}