Receiving an Ajax Request in a Servlet using ObjectInputStream? - ajax

Question

I am sending my Ajax Request in the following format
xmlhttp.open("POST","http://172.16.xx.xx:8080/ajax/validate",true);
xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
xmlhttp.send(send); //where send is a string retrieved from textarea
This is my Servlet code
ObjectInputStream in =new ObjectInputStream(request.getInputStream());
String inputxmlstring=(String) in.readObject();
I am getting the following exception
java.io.StreamCorruptedException: invalid stream header: 3C3F786D
What is the problem with the code? Is there anything wrong with my request header content type?
EDIT 1
BufferedInputStream in =new BufferedInputStream(req.getInputStream());
byte[] buf=new byte[req.getContentLength()];
while(in.available()>0)
{
in.read(buf);
}
String inputxmlstring=new String(buf);
System.out.println(inputxmlstring);
If I use this code for Servlet I get the following error
14:13:27,828 INFO [STDOUT] [Fatal Error] :1:1: Content is not allowed in prolog
.
14:13:27,843 INFO [STDOUT] org.xml.sax.SAXParseException: Content is not allowe
d in prolog.
EDIT 2
I use this code to parse. The String inputxmlstring has been used in Edit1.
DocumentBuilderFactory fty1 = DocumentBuilderFactory.newInstance();
fty1.setNamespaceAware(true);
DocumentBuilder builder1 = fty1.newDocumentBuilder();
ByteArrayInputStream bais1 = new ByteArrayInputStream(inputxmlstring.getBytes());
Document xmldoc1=builder1.parse(bais1);

Answer 1

You should use the ObjectInputStream only if you know the other end it was written using ObjectOutputStream.
When the client uses ObjectOutputStream, it writes special bytes indicating it is object stream. If these bytes are not present ObjectInputStream will throw StreamCorruptedException.
In your case you should read using request.getInputStream() because the XMLHttpRequest is not sending using ObjectOutputStream.