session.java

值得一看的J2ME_J2EE结合使用经典例程

    /**
     * Load movie data.
     *
     * @param  ml  the movie list to populate with the data.
     */
    public void loadMovies(MovieList ml) {
	HttpConnection conn = null;
	DataInputStream in = null;

	try {
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX/3);
            String message = MessageConstants.DISPLAY_MOVIES + "^";
	    conn = open(smartTicket.servlet, message);
            in = conn.openDataInputStream();
            smartTicket.updateGauge(2*GaugeForm.GAUGE_MAX/3);

            int count = in.readInt();
            ml.init(count);
            for (int i = 0; i != count; i++) {
                ml.addMovie(in.readInt(), in.readUTF(), in.readUTF(), 
                            in.readUTF());
            }
            
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX);
            smartTicket.stopLoading();
        } catch (Exception e) {
            smartTicket.stopLoading(e);
        } finally {
	    close(conn, in);
        }
    }
    
    /**
     * Load a poster.
     *
     * @param  ic  the ImageCanvas on which to display the poster.
     * @param  posterURL  the URL of the poster.
     */    
    public void loadPoster(ImageCanvas ic, String posterURL) {
        HttpConnection conn = null;
        DataInputStream is = null;

        try {
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX/3);
            conn = open(posterURL);
            is = conn.openDataInputStream();
            smartTicket.updateGauge(2*GaugeForm.GAUGE_MAX/3);

            int size = (int)(conn.getLength());
            if (size < 0) {
                size = 12000;   // Make a guess
            }
            byte[] buf = new byte[size];
            int offset = 0;
            int remaining = 0;
            while ((remaining = size - offset) > 0) {
                int len = is.read(buf, offset, remaining);
                if (len < 0)
                    break;
                offset += len;
            }
            if (remaining < 0) {
                throw new IOException("image not read completely");
            }
            ic.setImage(Image.createImage(buf, 0, offset));
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX);
            smartTicket.stopLoading();
        } catch (Exception e) {
            smartTicket.stopLoading(e);
        } finally {
	    close(conn, is);
        }
    }

    /**
     * Load the locations for the given movie.
     *
     * @param  ll  the location list to populate.
     * @param  movieID  the ID of the movie.
     */
    public void loadLocations(LocationList ll, int movieID) {
	HttpConnection conn = null;
	DataInputStream in = null;

	try {
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX/3);
            String message = MessageConstants.DISPLAY_LOCATIONS + 
		"^" + movieID;
	    conn = open(smartTicket.servlet, message);
            in = conn.openDataInputStream();
            smartTicket.updateGauge(2*GaugeForm.GAUGE_MAX/3);
            
            int count = in.readInt();
            ll.init(count);
            for (int i = 0; i != count; i++) {
                ll.addLocation(in.readInt(), in.readUTF());
            }

            smartTicket.updateGauge(GaugeForm.GAUGE_MAX);
            smartTicket.stopLoading();
        } catch (Exception e) {
            smartTicket.stopLoading(e);
        } finally {
	    close(conn, in);
        }
    }

    /**
     * Load showtimes for the given movie at the given location.
     *
     * @param  sl  the list to populate with showtime data.
     * @param  movieID  the ID of the movie.
     * @param  locationID  the ID of the location.
     */
    public void loadShowtimes(ShowtimeList sl, int movieID, 
			      int locationID) {
	HttpConnection conn = null;
	DataInputStream in = null;

	try {
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX/3);
            String message = MessageConstants.DISPLAY_SHOWTIMES + 
		"^" + movieID + "," + locationID;
	    conn = open(smartTicket.servlet, message);
            in = conn.openDataInputStream();
            smartTicket.updateGauge(2*GaugeForm.GAUGE_MAX/3);

            int count = in.readInt();
            sl.init(count);
            for (int i = 0; i != count; i++) {
                sl.addShowtime(in.readInt(), in.readUTF());
            }

            smartTicket.updateGauge(GaugeForm.GAUGE_MAX);
            smartTicket.stopLoading();
        } catch (Exception e) {
            smartTicket.stopLoading(e);
        } finally {
	    close(conn, in);
        }
    }

    /**
     * Load the given seating canvas with the data of the seating
     * plan for the given show.
     *
     * @param  sc  the seating canvas which needs the data.
     * @param  showID  the ID of the show.
     * @param  movieTitle  the title of the movie (for display).
     * @param  showtime  the time of the movie (for display).
     */
    public void loadSeatingPlan(SeatingCanvas sc, int showID,
                                String movieTitle, String showtime) {
	HttpConnection conn = null;
	DataInputStream in = null;

	try {
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX/3);
            String message = MessageConstants.DISPLAY_SEATINGPLAN + 
		"^" + showID;
	    conn = open(smartTicket.servlet, message);
            in = conn.openDataInputStream();
            smartTicket.updateGauge(2*GaugeForm.GAUGE_MAX/3);
            
            int rows = in.read();
            rowSize = in.read();
            byte[] seats = new byte[rows*rowSize];
            in.readFully(seats);
            sc.init(seats, rowSize, movieTitle, showtime);

            smartTicket.updateGauge(GaugeForm.GAUGE_MAX);
            smartTicket.stopLoading();
        } catch (Exception e) {
            smartTicket.stopLoading(e);
        } finally {
	    close(conn, in);
        }
    }
    
    /**
     * Reserve the selected seats.
     *
     * @param cf the confirmation form into which the confirmation
     * data should be loaded.
     * @param selectedSeats the indices of the selected seats in the
     * byte array representing the seating plan.
     * @param movieTitle the title of the movie (for display).
     * @param showtime the time of the showing (for display).
     */
    public void reserveSeats(ConfirmForm cf, int[] selectedSeats,
                             String movieTitle, String showtime) {
	HttpConnection conn = null;
	DataInputStream in = null;

        try {
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX/2);

            StringBuffer messageBuf = new StringBuffer(30);
            messageBuf.append(MessageConstants.RESERVE_SEATS);
            messageBuf.append('^');
            if (selectedSeats.length > 0) {
                messageBuf.append(selectedSeats[0] / rowSize);
                messageBuf.append(',');
                messageBuf.append(selectedSeats[0] % rowSize);
                for (int i = 1; i != selectedSeats.length; i++) {
                    messageBuf.append(',');
                    messageBuf.append(selectedSeats[i] / rowSize);
                    messageBuf.append(',');
                    messageBuf.append(selectedSeats[i] % rowSize);
                }
            }
	    conn = open(smartTicket.servlet, 
                                         messageBuf.toString());
            in = conn.openDataInputStream();
            cf.init(movieTitle, showtime, selectedSeats.length);
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX);
            smartTicket.stopLoading();
        } catch (Exception e) {
            smartTicket.stopLoading(e);
        } finally {
	    close(conn, in);
        }
    }

    /**
     * Confirm the purchase.
     *
     * @param creditCardCheck the last four digits of the credit card
     * number, as a security check.
     */
    public void confirmSeats(String creditCardCheck) {
	HttpConnection conn = null;
	DataInputStream in = null;

        try {
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX/2);
            String message = MessageConstants.CONFIRM_SEATS + 
		"^" + creditCardCheck;
	    conn = open(smartTicket.servlet, message);
            in = conn.openDataInputStream();
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX);
            smartTicket.stopLoading();
        } catch (Exception e) {
            smartTicket.stopLoading(e);
        } finally {
	    close(conn, in);
        }
    }

    /**
     * Cancel the purchase.
     */
    public void cancelSeats() {
	HttpConnection conn = null;
	DataInputStream in = null;

        try {
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX/2);
            String message = MessageConstants.CANCEL_SEATS + "^";
	    conn = open(smartTicket.servlet, message);
            in = conn.openDataInputStream();
            smartTicket.updateGauge(GaugeForm.GAUGE_MAX);
            smartTicket.stopLoading();
        } catch (Exception e) {
            smartTicket.stopLoading(e);
        } finally {
	    close(conn, in);
        }
    }

    /* Helper methods. */

    /**
     * Open the record store for storing localized messages.
     */
    public RecordStore openMessageStore(boolean create) 
	throws RecordStoreException {
	RecordStore rs;
	try {
	    rs = RecordStore.openRecordStore(MESSAGE_STORE_NAME, create);
	} catch (RecordStoreNotFoundException rsnfe) {
	    return null;
	}
	return rs;
    }

    static HttpConnection open(String url) 
        throws IOException
    {
        HttpConnection conn = (HttpConnection) Connector.open(url);
        conn.setRequestProperty("User-Agent", 
	    System.getProperty("microedition.profiles"));
        return conn;
    }

    /**
     * Open a connection, post a command, and check the response.
     *
     * The URL is opened and the command is written to the output
     * stream and the OutputStream is closed.  If there is a cookie
     * in the response, it is saved.
     *
     * @param url to open a connection for
     * @param command to POST to the stream
     * @returns an open HttpConnection
     * @exception IOException if any exception occurs
     * @exception ApplicationException if servlet reported an error
     */
    static HttpConnection open(String url, String message)
        throws IOException, ApplicationException
    {
        HttpConnection conn = open(url);
        conn.setRequestMethod(HttpConnection.POST);
        DataOutputStream os = null;
        message = message + '\n';
        try {
            os = conn.openDataOutputStream();
            os.write(message.getBytes());
        } finally {
            if (os != null) {
                os.close();
            }
        }

        // If the server reports an error, let's report it.
        if (conn.getResponseCode() == HttpConnection.HTTP_INTERNAL_ERROR) {
            String msg = conn.getHeaderField("Reason-Phrase");
            if (msg == null) {
                // This shouldn't happen (?).
                msg = "Internal Server Error";
            }
            throw new ApplicationException(Integer.parseInt(msg));
        }
        checkResponseCode(conn);
        return conn;
    }

    /**
     * Close the connection and streams.
     */
    static void close(HttpConnection conn, InputStream is) {
	if (is != null) {
	    try {
		is.close();
	    } catch (IOException ignore) {
		// ignore
	    }
	}
	if (conn != null) {
	    try {
		conn.close();
	    } catch (IOException ignore) {
		// ignore
	    }
	}
    }

    /**
     * Get the response code out and throw an error if it is not HTTP_OK.
     */
    static void checkResponseCode(HttpConnection conn) throws IOException {
        int code = conn.getResponseCode();
        if (code != HttpConnection.HTTP_OK) {
            throw new IOException(code + "; " + conn.getResponseMessage());
        }
    }
}