Question

I’m seeking a better way to extract data from a String that contains a HTTP header. For example, I’d like to get the number 160 from the content length portion of the string: “Content-Length: 160\r\n”.

It appears that all the data in the HTTP header is preceded with a name, colon and space, and after the value immediately follows the ‘\r’ and ‘\n’ characters.

At the moment I am doing this:

int contentLengthIndex = serverHeader.lastIndexOf("Content-Length: ");
int contentLastIndex = serverHeader.length()-1;
String contentText = serverHeader.substring(contentLengthIndex + 16, contentLastIndex);
contentText = contentText.replaceAll("(\\r|\\n)", "");
int contentLength = Integer.parseInt(contentText);

But it seems messy and it is only good for getting the “Content-Length” at the end of the string. Is there a better more universal solution for extracting values from a String containing a HTTP header that can be adjusted to work for obtaining both int values or String values?

I should also mention that the connection needs to be able return data back to the browser after a request, which from my understanding prevents me from reaping the benefits of using HttpURLConnection.

Answer 1

A quick solution will be:

new Scanner(serverHeader).useDelimiter("[^\\d]+").nextInt());

The other way if you want to create a Hashtable of the headers:

 String[] fields = serverHeader.trim().split(":");

 String key = fields[0].trim();
 String value = fields[1].trim();

I am not sure why you are doing this manual, there is already API for this!