How do I write to an OutputStream using DefaultHttpClient?

Question

How do I get an OutputStream using org.apache.http.impl.client.DefaultHttpClient?

I'm looking to write a long string to an output stream.

Using HttpURLConnection you would implement it like so:

HttpURLConnection connection = (HttpURLConnection)url.openConnection();
OutputStream out = connection.getOutputStream();
Writer wout = new OutputStreamWriter(out);
writeXml(wout);

Is there a method using DefaultHttpClient similar to what I have above? How would I write to an OutputStream using DefaultHttpClient instead of HttpURLConnection?

e.g

DefaultHttpClient client = new DefaultHttpClient();

OutputStream outstream = (get OutputStream somehow)
Writer wout = new OutputStreamWriter(out);

Answer 1

I know that another answer has already been accepted, just for the record this is how one can write content out with HttpClient without intermediate buffering in memory.

    AbstractHttpEntity entity = new AbstractHttpEntity() {

        public boolean isRepeatable() {
            return false;
        }

        public long getContentLength() {
            return -1;
        }

        public boolean isStreaming() {
            return false;
        }

        public InputStream getContent() throws IOException {
            // Should be implemented as well but is irrelevant for this case
            throw new UnsupportedOperationException();
        }

        public void writeTo(final OutputStream outstream) throws IOException {
            Writer writer = new OutputStreamWriter(outstream, "UTF-8");
            writeXml(writer);
            writer.flush();
        }

    };
    HttpPost request = new HttpPost(uri);
    request.setEntity(entity);

Answer 2

You can't get an OutputStream from BasicHttpClient directly. You have to create an HttpUriRequest object and give it an HttpEntity that encapsulates the content you want to sent. For instance, if your output is small enough to fit in memory, you might do the following:

// Produce the output
ByteArrayOutputStream out = new ByteArrayOutputStream();
Writer writer = new OutputStreamWriter(out, "UTF-8");
writeXml(writer);

// Create the request
HttpPost request = new HttpPost(uri);
request.setEntity(new ByteArrayEntity(out.toByteArray()));

// Send the request
DefaultHttpClient client = new DefaultHttpClient();
HttpResponse response = client.execute(request);

If the data is large enough that you need to stream it, it becomes more difficult because there's no HttpEntity implementation that accepts an OutputStream. You'd need to write to a temp file and use FileEntity or possibly set up a pipe and use InputStreamEntity

EDIT See oleg's answer for sample code that demonstrates how to stream the content - you don't need a temp file or pipe after all.