Okhttp网络请求

private static OkHttpUtils okHttpUtils;    private OkHttpClient okHttpClient;    private OkHttpUtils(){    okHttpClient=new OkHttpClient();    }    public static synchronized OkHttpUtils getInstance(){        if (okHttpUtils==null)okHttpUtils=new OkHttpUtils();        return okHttpUtils;    }    public void sendGet(String url, Callback callback){        Request build = new Request.Builder().url(url).build();        okHttpClient.newCall(build).enqueue(callback);    }    public void sendPost(String url, RequestBody body, Callback callback){        Request build = new Request.Builder().url(url).post(body).build();        okHttpClient.newCall(build).enqueue(callback);    }