source: java/ProxySettings/src/net/oni2/ProxySettings.java

package net.oni2;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.Serializable;
import java.net.InetSocketAddress;
import java.net.MalformedURLException;
import java.net.Proxy;
import java.net.Proxy.Type;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.net.URLConnection;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.StaxDriver;

/**
 * @author Christian Illy
 */
public class ProxySettings implements Serializable {
        private static final long serialVersionUID = 7764207071836441954L;

        private static ProxySettings instance = new ProxySettings();

        private boolean useProxy = false;
        private String hostOrIp = "";
        private int port = 8080;

        private transient boolean validated = false;
        private transient boolean validatedOk = false;

        /**
         * Get the proxy for URL connections. Validates connection first if not
         * validated yet
         * 
         * @return Proxy
         */
        public Proxy getProxy() {
                if (!useProxy)
                        return Proxy.NO_PROXY;
                if (!validated)
                        validate();
                if (!validatedOk)
                        return Proxy.NO_PROXY;

                return new Proxy(Type.HTTP, new InetSocketAddress(hostOrIp, port));
        }

        /**
         * Check if a connection to the given proxy can be established
         * 
         * @return Data entered and connection Ok?
         */
        public boolean validate() {
                if (validated) {
                        return validatedOk;
                } else {
                        validated = true;
                        if (isValid()) {
                                try {
                                        URLConnection con = new URL(String.format("http://%s:%d",
                                                        hostOrIp, port)).openConnection();
                                        con.setConnectTimeout(1000);
                                        con.connect();
                                        validatedOk = true;
                                        return true;
                                } catch (MalformedURLException e) {
                                } catch (SocketTimeoutException e) {
                                } catch (IOException e) {
                                }
                        }
                        validatedOk = false;
                        return false;
                }
        }

        /**
         * @return Is data for both host and port entered?
         */
        public boolean isValid() {
                return (hostOrIp != null) && (port > 0);
        }

        /**
         * @return Should a proxy be used for connections?
         */
        public boolean isUseProxy() {
                return useProxy;
        }

        /**
         * @param use
         *            Should a proxy be used for connections?
         */
        public void setUseProxy(boolean use) {
                this.useProxy = use;
        }

        /**
         * @return Hostname or IP of host to use as proxy
         */
        public String getHostOrIp() {
                return hostOrIp;
        }

        /**
         * @param hoi
         *            Hostname or IP of host to use as proxy
         */
        public void setHostOrIp(String hoi) {
                validated = false;
                this.hostOrIp = hoi;
        }

        /**
         * @return Port number proxy is listening on
         */
        public int getPort() {
                return port;
        }

        /**
         * @param port
         *            Port number proxy is listening on
         */
        public void setPort(int port) {
                validated = false;
                this.port = port;
        }

        /**
         * Get the singleton instance
         * 
         * @return Singleton instance
         */
        public static ProxySettings getInstance() {
                return instance;
        }

        private static XStream getXStream() {
                XStream xs = new XStream(new StaxDriver());
                xs.alias("Proxy", ProxySettings.class);
                return xs;
        }

        /**
         * Serializes the settings to disk
         * 
         * @param settingsFile
         *            File to write to
         */
        public void serializeToFile(File settingsFile) {
                try {
                        FileOutputStream fos = new FileOutputStream(settingsFile);
                        XStream xs = getXStream();
                        xs.toXML(this, fos);
                        fos.close();
                } catch (FileNotFoundException e) {
                        e.printStackTrace();
                } catch (IOException e) {
                        e.printStackTrace();
                }
        }

        /**
         * Deserializes the settings from disk
         * 
         * @param settingsFile
         *            File to read from
         */
        public static void deserializeFromFile(File settingsFile) {
                try {
                        FileInputStream fis = new FileInputStream(settingsFile);
                        XStream xs = getXStream();
                        Object obj = xs.fromXML(fis);
                        if (obj instanceof ProxySettings)
                                instance = (ProxySettings) obj;
                        fis.close();
                } catch (FileNotFoundException e) {
                } catch (IOException e) {
                }
        }

}