Android AsyncTask给出了奇怪的行为

Question

我正在尝试进行API调用以获取此类YouTube视频列表：

    @Override
    protected String doInBackground(String... theParams) 
    {
        String myUrl = theParams[0];
        final String key = "my_key";
        final String channelId = "UCoLEarNS6E-Kbzoya_p7k2Q";

        String charset = "UTF-8";           
        String response = null;

        try 
        {                           
            String query = String.format("key=%s&channelId=%s&part=snippet,id&order=date&maxResults=20", 
                     URLEncoder.encode( key, charset ) ,
                     URLEncoder.encode( channelId, charset )
                    );

            final URL url = new URL( myUrl + "?" + query );

                final HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            conn.setDoOutput(true); 
            conn.setRequestMethod("POST");

            conn.setDoOutput(true);
            conn.setUseCaches(false);

            conn.connect();

            final InputStream is = conn.getInputStream();
            final byte[] buffer = new byte[8196];
            int readCount;
            final StringBuilder builder = new StringBuilder();
            while ((readCount = is.read(buffer)) > -1) 
            {
                builder.append(new String(buffer, 0, readCount));
            }

            response = builder.toString();      
        } 
        catch (IOException e) 
        {
             sendEmail ( "MyQuestionsActivity Network Error" , "Error: " + e.getMessage() );
        }

        return response;
    }

但它不断出错。如果我将网址粘贴到浏览器中，它会返回一些JSON。但在这种情况下，我发出的sendEmail实用程序是从e.getMessag（）发送此错误：

Error: https://www.googleapis.com/youtube/v3/search?key=my_key&channelId=UCoLEarNS6E-Kbzoya_p7k2Q&part=snippet,id&order=date&maxResults=20

有人知道什么是不对的吗？我的catLog也遇到了一些问题，所以我无法看到异常。