source: josm/src/org/openstreetmap/josm/data/ServerSidePreferences.java@ 195

package org.openstreetmap.josm.data;

import static org.openstreetmap.josm.tools.I18n.tr;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StringReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Collection;
import java.util.Collections;
import java.util.Map.Entry;

import javax.swing.JOptionPane;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.io.OsmConnection;
import org.openstreetmap.josm.io.XmlWriter;
import org.openstreetmap.josm.tools.Base64;
import org.openstreetmap.josm.tools.XmlObjectParser;

/**
 * This class tweak the Preferences class to provide server side preference settings, as example
 * used in the applet version.
 * 
 * @author Imi
 */
public class ServerSidePreferences extends Preferences {

        private final Connection connection;

        private class Connection extends OsmConnection {
                URL serverUrl;
                public Connection(URL serverUrl) {
                        this.serverUrl = serverUrl;
                }
                public String download() {
                        try {
                                System.out.println("reading preferenced from "+serverUrl);
                                HttpURLConnection con = (HttpURLConnection)serverUrl.openConnection();
                                addAuth(con);
                                con.connect();
                                BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream()));
                                StringBuilder b = new StringBuilder();
                                for (String line = reader.readLine(); line != null; line = reader.readLine()) {
                                        b.append(line);
                                        b.append("\n");
                                }
                                con.disconnect();
                                return b.toString();
                        } catch (IOException e) {
                                e.printStackTrace();
                        }
                        return null;
                }
                public void upload(String s) {
                        try {
                                URL u = new URL(getPreferencesDir());
                                System.out.println("uplaoding preferences to "+u);
                                HttpURLConnection con = (HttpURLConnection)u.openConnection();
                                con.addRequestProperty("Authorization", "Basic "+Base64.encode(get("osm-server.username")+":"+get("osm-server.password")));
                                con.setRequestMethod("POST");
                                con.setDoOutput(true);
                                con.connect();
                                PrintWriter out = new PrintWriter(new OutputStreamWriter(con.getOutputStream()));
                                out.println(s);
                                out.close();
                                con.getInputStream().close();
                                con.disconnect();
                                JOptionPane.showMessageDialog(Main.parent, tr("Preferences stored on {0}", u.getHost()));
                        } catch (Exception e) {
                                e.printStackTrace();
                                JOptionPane.showMessageDialog(Main.parent, tr("Could not upload preferences. Reason: {0}", e.getMessage()));
                        }
                }
        }

        public ServerSidePreferences(URL serverUrl) {
                Connection connection = null;
                try {
                        connection = new Connection(new URL(serverUrl+"/user/preferences"));
                } catch (MalformedURLException e) {
                        e.printStackTrace();
                        JOptionPane.showMessageDialog(Main.parent, tr("Could not load preferenced from server."));
                }
                this.connection = connection;
        }

        @Override public String getPreferencesDir() {
                return connection.serverUrl.toString();
        }

        /**
         * Do nothing on load. Preferences are loaded with download().
         */
        @Override public void load() throws IOException {
        }

        /**
         * Do nothing on save. Preferences are uploaded using upload().
         */
        @Override protected void save() {
        }

        public static class Prop {
                public String key;
                public String value;
        }

        public void download(String userName, String password) {
                resetToDefault();
                if (!properties.containsKey("osm-server.username") && userName != null)
                        properties.put("osm-server.username", userName);
                if (!properties.containsKey("osm-server.password") && password != null)
                        properties.put("osm-server.password", password);
        Reader in = new StringReader(connection.download());
                try {
                XmlObjectParser.Uniform<Prop> parser = new XmlObjectParser.Uniform<Prop>(in, "tag", Prop.class);
                for (Prop p : parser)
                        properties.put(p.key, p.value);
        } catch (RuntimeException e) {
                e.printStackTrace();
        }
        }

        /**
         * Use this instead of save() for the ServerSidePreferences, since uploads
         * are costly while save is called often.
         * 
         * This is triggered by an explicit menu option.
         */
        public void upload() {
                StringBuilder b = new StringBuilder("<preferences>\n");
                for (Entry<String, String> p : properties.entrySet()) {
                        b.append("<tag key='");
                        b.append(XmlWriter.encode(p.getKey()));
                        b.append("' value='");
                        b.append(XmlWriter.encode(p.getValue()));
                        b.append("' />\n");
                }
                b.append("</preferences>");
                connection.upload(b.toString());
        }

        @Override public Collection<Bookmark> loadBookmarks() {
                return Collections.<Bookmark>emptyList();
        }

        @Override public void saveBookmarks(Collection<Bookmark> bookmarks) {
        }
}