CODEWITHSUNDEEP
javaserverresponseresponse-headershttp-content-length
Methma
Methma

Reputation: 162

How to remove Content-length header from HTTP response generated in a simple server?

Following is my sample HTTP server. I need to remove the 'Content-length:' header generated at the response. I have tried many approaches and not succeded. Is there any way to remove the content-length from server response?

public class SimpleHttpServer {

    public static void main(String[] args) throws Exception {
        HttpServer server = HttpServer.create(new InetSocketAddress(9000), 0);
        server.createContext("/test", new TestHandler());
        server.setExecutor(null); // creates a default executor
        server.start();
    }

    static class TestHandler implements HttpHandler {
        public void handle(HttpExchange t) throws IOException {
            byte[] response = "Welcome to Test Server..!!\n".getBytes();
            t.sendResponseHeaders(200, response.length);
            OutputStream os = t.getResponseBody();
            os.write(response);
            os.close();
        }
    }
}

Upvotes: 3

Views: 9866

Answers (3)

hovanessyan
hovanessyan

Reputation: 31473

Content-Length header is always set, unless it's 0 or -1;

If you check the source of HttpExchange sendResponseHeaders() you will find this snippet, which contains the relevant logic:

As you can see when contentLen == 0 and !http10, this header is added "Transfer-encoding", "chunked".

You can use getResponseHeaders(), which returns a mutable map of headers, to set any response headers, except "Date" and "Transfer-encoding" - read the linked source code to see why.

207        if (contentLen == 0) {
208            if (http10) {
209                o.setWrappedStream (new UndefLengthOutputStream (this, ros));
210                close = true;
211            } else {
212                rspHdrs.set ("Transfer-encoding", "chunked");
213                o.setWrappedStream (new ChunkedOutputStream (this, ros));
214            }
215        } else {
216            if (contentLen == -1) {
217                noContentToSend = true;
218                contentLen = 0;
219            }
220            /* content len might already be set, eg to implement HEAD resp */
221            if (rspHdrs.getFirst ("Content-length") == null) {
222                rspHdrs.set ("Content-length", Long.toString(contentLen));
223            }
224            o.setWrappedStream (new FixedLengthOutputStream (this, ros, contentLen));
225        }

If you need more flexibility, you need to use other constructs, rather than plain HttpExchange. Classes come with constraints, default behavior and built in a certain way.

Upvotes: 0

Cesar Loachamin
Cesar Loachamin

Reputation: 2738

You have to send 0 in the response length, as specified in the javadoc for the sendResponseHeaders:

responseLength - if > 0, specifies a fixed response body length and that exact number of bytes must be written to the stream acquired from getResponseBody(), or else if equal to 0, then chunked encoding is used, and an arbitrary number of bytes may be written. if <= -1, then no response body length is specified and no response body may be written.

t.sendResponseHeaders(200, 0);

This means it would not send to the browser the length of the response and also not send the Content-Length header instead it sends the response as chunked encoding that as you indicate this is for a test it could be fine.

Chunked transfer encoding is a streaming data transfer mechanism available in version 1.1 of the Hypertext Transfer Protocol (HTTP). In chunked transfer encoding, the data stream is divided into a series of non-overlapping "chunks". The chunks are sent out and received independently of one another. No knowledge of the data stream outside the currently-being-processed chunk is necessary for both the sender and the receiver at any given time.

Upvotes: 0

Andrew
Andrew

Reputation: 49656

A workaround could be:

t.sendResponseHeaders(200, 0);

Note that

If the response length parameter is 0, then chunked transfer encoding is used and an arbitrary amount of data may be sent.

Upvotes: 1

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