We are getting some very weird behavior in Android. Our network stack (that talks to a REST server) works fine in almost all situations, except when we do a GET shortly after doing a larger POST. What appears to be happening is that the Output stream is not flushing, and ends up sending the last line that was in there when the new socket is opened. Please note, each connection is a new object created, so this is unexpected behavior. First, the error code that seems to point me to the output stream, these are from the server logs.
10.1.8.195 – – [07/Nov/2012:13:36:28 -0700] “POST /iou/lender HTTP/1.1” 200 28 “-” “Android”
10.1.8.195 – – [07/Nov/2012:13:36:36 -0700] “————V2ymHFg03ehbqgZCaKO6jy” 400 173 “-” “-“
That attempt after should be a GET that then pulls the data from the server that includes the new entry added via the POST. However, all we get is again what appears to be the last line from the output stream from the POST. Here is our core code for the network stack, if more of the surrounding code is needed, let me know.
public Object serverConnect(String url, String method,
Hashtable<String, Object> params) {
HttpConnection c = null;
InputStream is = null;
OutputStream out = null;
ByteArrayOutputStream postDataByteArrayImage = new ByteArrayOutputStream();
byte[] data;
String boundry = "----------V2ymHFg03ehbqgZCaKO6jy";
try {
if (!url.startsWith("/")) {
url = "/" + url;
}
String uri = Control.URL_Secure + Control.dtserver + ":"
+ Control.port + url;
ByteArrayOutputStream postDataByteArray = new ByteArrayOutputStream();
params.put("sessionId", Control.sessionId);
if (method.equals("GET")) {
uri = uri + "?";
Enumeration enumParams = params.keys();
while (enumParams.hasMoreElements()) {
if (!uri.endsWith("?")) {
uri = uri + "&";
}
String key = (String) enumParams.nextElement();
uri = uri
+ key
+ "="
+ java.net.URLEncoder.encode((String) params
.get(key));
}
} else if (method.equals("POST")) {
Enumeration enumParams = params.keys();
postDataByteArray.write(("--").getBytes());
postDataByteArray.write((boundry).getBytes());
postDataByteArray.write(("\r\n").getBytes());
while (enumParams.hasMoreElements()) {
String key = (String) enumParams.nextElement();
if (!key.equals("image")){
postDataByteArray
.write(("Content-Disposition: form-data; name=\"")
.getBytes());
postDataByteArray.write((key).getBytes());
postDataByteArray.write(("\"").getBytes());
postDataByteArray.write(("\r\n\r\n").getBytes());
postDataByteArray.write(((String) params.get(key))
.getBytes());
postDataByteArray.write(("\r\n").getBytes());
postDataByteArray.write(("--").getBytes());
postDataByteArray.write(boundry.getBytes());
postDataByteArray.write(("\r\n").getBytes());
}
}
postDataByteArray.close();
}
Log.i("URL", uri);
URL urltoConenct = new URL(uri);
URLConnection connection = urltoConenct.openConnection();
HttpURLConnection urlConnection = (HttpURLConnection) connection;
URLConnection.setDefaultRequestProperty("Method", method); // default
urlConnection.setRequestProperty("User-Agent", "Android");
if (method.equals("POST")) {
urlConnection.setDoOutput(true);
urlConnection.setFixedLengthStreamingMode(postDataByteArray.toByteArray().length + postDataByteArrayImage.toByteArray().length);
urlConnection.setRequestProperty("Content-Type",
"multipart/form-data; boundary=" + boundry);
out = urlConnection.getOutputStream();
out.write(postDataByteArray.toByteArray());
out.write(postDataByteArrayImage.toByteArray());
out.close();
}
int response = 0;
try {
response = urlConnection.getResponseCode();
} catch (IOException e) {
if (e.toString()
.equals("java.io.IOException: Received authentication challenge is null"))
throw new RESTException(401, "Invalid Phone or Pin");
else
throw e;
}
if (response == HttpURLConnection.HTTP_OK) {
is = urlConnection.getInputStream();
if (is == null) {
return new IOException(
"Cannot open HTTP InputStream, aborting");
}
ByteArrayOutputStream bo = new ByteArrayOutputStream();
int ch;
int count = 0;
while ((ch = is.read()) != -1) {
bo.write(ch);
count++;
}
data = bo.toByteArray();
return new String(data);
} else if (response == 500) {
return new RESTException(500, "Internal server error");
} else {
RESTException x = new RESTException();
x.setCode(response);
try {
is = urlConnection.getInputStream();
if (is == null) {
x.setMessage("Unable to retrieve message");
return x;
}
ByteArrayOutputStream bo = new ByteArrayOutputStream();
int ch;
int count = 0;
while ((ch = is.read()) != -1) {
bo.write(ch);
count++;
}
data = bo.toByteArray();
String output = new String(data);
JSONObject obj;
try {
obj = new JSONObject(output);
JSONObject err = obj.getJSONArray("errors")
.getJSONObject(0);
x.setMessage(err.getString("message"));
} catch (JSONException e) {
Log.e("stuff", output);
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException e) {
// Damn you android! I'm using a REST service here, stop
// trying to interpret my errors!
x.setMessage("Unable to retrieve message");
}
return x;
}
} catch (Exception x) {
x.printStackTrace();
/*
* if (!retried && x.toString().equals(
* "java.io.IOException: Persistent connection dropped after first chunk sent, cannot retry"
* )) { retry = true; } if (!retry) { return x; }
*/
return x;
} finally {
try {
out.close();
} catch (Exception x) {
}
try {
is.close();
} catch (Exception x) {
}
try {
c.close();
} catch (Exception x) {
}
params.clear();
}
// return null;
}
After a very long time of frustration, we discovered that Android tries to keep a connection alive even if you manually call .close() on the connection. This worked fine for our GET methods, but POST methods left the socket in a state that it couldn’t then process a GET. Adding the following fixed all our problems: