如何从服务器的.txt文件中获取文本？

Question

获得null作为回报。请修复

public class HttpURLConnectionHandler {

protected String urlG = "http://mywebsite.000webhostapp.com/";

public String sendText() {
    try {
        URL url = new URL(urlG + "TopicContents/tryfile.txt");
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setDoInput(true);

        InputStream is = conn.getInputStream();
        BufferedReader rd = new BufferedReader(new InputStreamReader(is));
        String line;
        String response = "";
        while ((line = rd.readLine()) != null) {
            response = (response + line + "\n");
        }
        rd.close();
        return response;
    } catch (Exception e) {
        return "error: "+e.getMessage();
    }
}
}

returnig“error：null”我从2天开始尝试每一个方法从服务器获取文本文本中的文本。请帮忙;（

我可以使用echo n stuff将文件从.txt更改为php但是请帮我从服务器获取字符串