new Thread(new Runnable() {
          @Override
          public void run() {
            doRequest();
          }
        }).start();
//发起网络请求        
private void doRequest() {
  HttpURLConnection connection = null;
  BufferedReader reader = null;
  try {
    //1.获取 HttpURLConnection 实例.注意要用 https 才能获取到结果！
    URL url = new URL("https://www.baidu.com");
    connection = (HttpURLConnection) url.openConnection();
    //2.设置 HTTP 请求方式
    connection.setRequestMethod("GET");
    //3.设置连接超时和读取超时的毫秒数
    connection.setConnectTimeout(5000);
    connection.setReadTimeout(5000);
    //4.获取服务器返回的输入流
    InputStream inputStream = connection.getInputStream();
    //5.对获取的输入流进行读取
    reader = new BufferedReader(new InputStreamReader(inputStream));
    final StringBuilder response = new StringBuilder();
    String line;
    while ((line = reader.readLine()) != null) {
      response.append(line);
    }
    //然后处理读取到的信息 response。返回的结果是 HTML 代码，字符非常多。
    runOnUiThread(new Runnable() {
      @Override
      public void run() {
        tvResponse.setText(response.toString());

      }
    });
  } catch (MalformedURLException e) {
    e.printStackTrace();
  } catch (IOException e) {
    e.printStackTrace();
  } finally {
    if (reader != null) {
      try {
        reader.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
    if (connection != null) {
      connection.disconnect();
    }
  }
}