HttpUrlConnection.getInputStream returns empty stream in Android

问题

I make a GET request to a server using HttpUrlConnection. After connecting:

I get response code: 200
I get response message: OK
I get input stream, no exception thrown but:
- in a standalone program I get the body of the response, as expected:
{"name":"my name","birthday":"01/01/1970","id":"100002215110084"}
- in a android activity, the stream is empty (available() == 0), and thus I can't get any text out.

Any hint or trail to follow? Thanks.

EDIT: here it is the code

Please note: I use import java.net.HttpURLConnection; This is the standard http Java library. I don't want to use any other external library. In fact I did have problems in android using the library httpclient from apache (some of their anonymous .class can't be used by the apk compiler).

Well, the code:

URLConnection theConnection;
theConnection = new URL("www.example.com?query=value").openConnection(); 

theConnection.setRequestProperty("Accept-Charset", "UTF-8");

HttpURLConnection httpConn = (HttpURLConnection) theConnection;


int responseCode = httpConn.getResponseCode();
String responseMessage = httpConn.getResponseMessage();

InputStream is = null;
if (responseCode >= 400) {
    is = httpConn.getErrorStream();
} else {
    is = httpConn.getInputStream();
}


String resp = responseCode + "\n" + responseMessage + "\n>" + Util.streamToString(is) + "<\n";

return resp;

I see:

200
OK
the body of the response

but only

200 OK

in android

回答1:

Trying the code of Tomislav I've got the answer.

My function streamToString() used .available() to sense if there is any data received, and it returns 0 in Android. Surely, I called it too soon.

If I rather use readLine():

class Util {
public static String streamToString(InputStream is) throws IOException {
        StringBuilder sb = new StringBuilder();
        BufferedReader rd = new BufferedReader(new InputStreamReader(is));
        String line;
        while ((line = rd.readLine()) != null) {
            sb.append(line);
        }
        return sb.toString();
    }
}

then, it waits for the data to arrive.

Thanks.

回答2:

You can try with this code that will return response in String:

public String ReadHttpResponse(String url){
        StringBuilder sb= new StringBuilder();
        HttpClient client= new DefaultHttpClient();     
        HttpGet httpget = new HttpGet(url);     
        try {
            HttpResponse response = client.execute(httpget);
            StatusLine sl = response.getStatusLine();
            int sc = sl.getStatusCode();
            if (sc==200)
            {
                HttpEntity ent = response.getEntity();
                InputStream inpst = ent.getContent();
                BufferedReader rd= new BufferedReader(new InputStreamReader(inpst));
                String line;
                while ((line=rd.readLine())!=null)
                {
                    sb.append(line);
                }
            }
            else
            {
                Log.e("log_tag","I didn't  get the response!");
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return sb.toString();
    }

回答3:

The Stream data may not be ready, so you should check in a loop that the data in the stream is available before attempting to access it. Once the data is ready, you should read it and store in another place like a byte array; a binary stream object is a nice choice to read data as a byte array. The reason that a byte array is a better choice is because the data may be binary data like an image file, etc.

InputStream is = httpConnection.getInputStream();

byte[] bytes = null;

ByteArrayOutputStream baos = new ByteArrayOutputStream();

byte[] temp = new byte[is.available()];
while (is.read(temp, 0, temp.length) != -1) {
    baos.write(temp);
    temp = new byte[is.available()];
}

bytes = baos.toByteArray();

In the above code, bytes is the response as byte array. You can convert it to string if it is text data, for example data as utf-8 encoded text:

String text = new String(bytes, Charset.forName("utf-8"));

来源：https://stackoverflow.com/questions/15030026/httpurlconnection-getinputstream-returns-empty-stream-in-android

标签

android

inputstream

httpurlconnection