source: josm/src/org/openstreetmap/josm/io/OsmServerWriter.java@ 43

package org.openstreetmap.josm.io;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.UnknownHostException;
import java.util.Collection;
import java.util.HashMap;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.output.Format;
import org.jdom.output.XMLOutputter;
import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.osm.Key;
import org.openstreetmap.josm.data.osm.LineSegment;
import org.openstreetmap.josm.data.osm.Node;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.data.osm.Track;
import org.openstreetmap.josm.data.osm.visitor.OsmXmlVisitor;
import org.openstreetmap.josm.data.osm.visitor.Visitor;

/**
 * Class that uploades all changes to the osm server.
 * 
 * This is done like this: - All objects with id = 0 are uploaded as new, except
 * those in deleted, which are ignored - All objects in deleted list are
 * deleted. - All remaining objects with modified flag set are updated.
 * 
 * This class implements visitor and will perform the correct upload action on
 * the visited element.
 * 
 * @author imi
 */
public class OsmServerWriter extends OsmConnection implements Visitor {

        /**
         * Send the dataset to the server. Ask the user first and does nothing if he
         * does not want to send the data.
         */
        public void uploadOsm(Collection<OsmPrimitive> list) throws JDOMException {
                initAuthentication();

                try {
                        for (OsmPrimitive osm : list)
                                osm.visit(this);
                } catch (RuntimeException e) {
                        throw new JDOMException("An error occoured: ", e);
                }
        }

        /**
         * Upload a single node.
         */
        public void visit(Node n) {
                if (n.id == 0 && !n.isDeleted()) {
                        setCredits(n);
                        sendRequest("PUT", "newnode", n, true);
                } else if (n.isDeleted()) {
                        sendRequest("DELETE", "node/" + n.id, n, false);
                } else {
                        sendRequest("PUT", "node/" + n.id, n, true);
                }
        }

        /**
         * Upload a line segment (without the nodes).
         */
        public void visit(LineSegment ls) {
                if (ls.id == 0 && !ls.isDeleted()) {
                        setCredits(ls);
                        sendRequest("PUT", "newsegment", ls, true);
                } else if (ls.isDeleted()) {
                        sendRequest("DELETE", "segment/" + ls.id, ls, false);
                } else {
                        sendRequest("PUT", "segment/" + ls.id, ls, true);
                }
        }

        /**
         * Add the created_by - property to indicate that JOSM was the
         * creating application.
         * @param osm The primitive to add the credits to
         */
        private void setCredits(OsmPrimitive osm) {
                if (osm.keys == null)
                        osm.keys = new HashMap<Key, String>();
                osm.keys.put(Key.get("created_by"), "JOSM");
        }

        public void visit(Track t) {
                // not implemented in server
        }

        public void visit(Key k) {
                // not implemented in server
        }

        /**
         * Read an long from the input stream and return it.
         */
        private long readId(InputStream inputStream) throws IOException {
                BufferedReader in = new BufferedReader(new InputStreamReader(
                                inputStream));
                String s = in.readLine();
                if (s == null)
                        return 0;
                try {
                        return Long.parseLong(s);
                } catch (NumberFormatException e) {
                        return 0;
                }
        }

        @SuppressWarnings("unchecked")
        private void sendRequest(String requestMethod, String urlSuffix,
                        OsmPrimitive osm, boolean addBody) {
                try {
                        URL url = new URL(Main.pref.osmDataServer + "/" + urlSuffix);
                        HttpURLConnection con = (HttpURLConnection) url.openConnection();
                        con.setConnectTimeout(20000);
                        con.setRequestMethod(requestMethod);
                        if (addBody)
                                con.setDoOutput(true);
                        con.connect();

                        if (addBody) {
                                OsmXmlVisitor visitor = new OsmXmlVisitor(false);
                                osm.visit(visitor);
                                Element root = new Element("osm");
                                root.setAttribute("version", "0.2");
                                root.getChildren().add(visitor.element);
                                XMLOutputter xmlOut = new XMLOutputter(Format.getPrettyFormat());
                                OutputStream out = con.getOutputStream();
                                Document doc = new Document(root);
                                xmlOut.output(doc, out);
                                out.close();
                        }

                        int retCode = con.getResponseCode();
                        if (retCode == 200 && osm.id == 0)
                                osm.id = readId(con.getInputStream());
                        con.disconnect();
                } catch (UnknownHostException e) {
                        throw new RuntimeException("Unknown host: "+e.getMessage(), e);
                } catch (Exception e) {
                        throw new RuntimeException(e.getMessage(), e);
                }
        }
}