webimageplugin.java

openmap java写的开源数字地图程序. 用applet实现,可以像google map 那样放大缩小地图.

/* **********************************************************************
 * $Source: /cvs/distapps/openmap/src/openmap/com/bbn/openmap/plugin/WebImagePlugIn.java,v $
 * $Revision: 1.4.2.2 $ 
 * $Date: 2006/01/13 21:04:22 $ 
 * $Author: dietrick $
 *
 * Code provided by Raj Singh from Syncline, [e-mail]
 * Updates provided by Holger Kohler, [e-mail]
 * *********************************************************************
 */

package com.bbn.openmap.plugin;

import java.awt.Component;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.util.Iterator;
import java.util.Vector;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

import com.bbn.openmap.Layer;
import com.bbn.openmap.image.ImageServerConstants;
import com.bbn.openmap.omGraphics.OMGraphicList;
import com.bbn.openmap.omGraphics.OMRaster;
import com.bbn.openmap.proj.Projection;
import com.bbn.openmap.util.Debug;
import com.bbn.openmap.util.PropUtils;

/**
 * This class asks for an image from a web server. How it asks for that image is
 * what is abstract.
 */
public abstract class WebImagePlugIn extends AbstractPlugIn implements
        ImageServerConstants {

    /** For convenience. */
    protected PlugInLayer layer = null;

    /** The last projection object received. */
    protected Projection currentProjection = null;

    /**
     * Create the query to be sent to the server, based on current settings.
     */
    public abstract String createQueryString(Projection p);

    /**
     * The getRectangle call is the main call into the PlugIn module. The module
     * is expected to fill the graphics list with objects that are within the
     * screen parameters passed.
     * 
     * @param p projection of the screen, holding scale, center coords, height,
     *        width.
     */
    public OMGraphicList getRectangle(Projection p) {
        OMGraphicList list = new OMGraphicList();

        currentProjection = p;

        String urlString = createQueryString(p);

        if (Debug.debugging("plugin")) {
            Debug.output("WebImagePlugIn.getRectangle() with \"" + urlString
                    + "\"");
        }

        if (urlString == null) {
            return list;
        }

        java.net.URL url = null;

        try {
            url = new java.net.URL(urlString);
            java.net.HttpURLConnection urlc = (java.net.HttpURLConnection) url.openConnection();

            if (Debug.debugging("plugin")) {
                Debug.output("url content type: " + urlc.getContentType());
            }

            if (urlc == null || urlc.getContentType() == null) {
                if (layer != null) {
                    layer.fireRequestMessage(getName()
                            + ": unable to connect to " + getServerName());
                } else {
                    Debug.error(getName() + ": unable to connect to "
                            + getServerName());
                }
                return list;
            }

            // text
            if (urlc.getContentType().startsWith("text")) {
                java.io.BufferedReader bin = new java.io.BufferedReader(new java.io.InputStreamReader(urlc.getInputStream()));
                String st;
                String message = "";
                while ((st = bin.readLine()) != null) {
                    message += st;
                }

                // Debug.error(message);
                // How about we toss the message out to the user
                // instead?
                if (layer != null) {
                    layer.fireRequestMessage(message);
                }

                // image
            } else if (urlc.getContentType().startsWith("image")) {
                // disconnect and reconnect in ImageIcon is very
                // expensive
                // urlc.disconnect();
                // ImageIcon ii = new ImageIcon(url);

                // this doesn't work always
                // ImageIcon ii = new ImageIcon((Image)
                // urlc.getContent());

                // the best way, no reconnect, but can be an
                // additional 'in memory' image
                InputStream in = urlc.getInputStream();
                // ------- Testing without this
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                int buflen = 2048; // 2k blocks
                byte buf[] = new byte[buflen];
                int len = -1;
                while ((len = in.read(buf, 0, buflen)) != -1) {
                    out.write(buf, 0, len);
                }
                out.flush();
                out.close();
                ImageIcon ii = new ImageIcon(out.toByteArray());

                // -------- To here, replaced by two lines below...

                // DFD - I've seen problems with these lines below handling PNG
                // images, and with some servers with some coverages, like there
                // was something in the image under certain conditions that made
                // it tough to view. So while it might be more memory efficient
                // to do the code below, we'll error on the side of correctness
                // until we figure out what's going on.

                // FileCacheImageInputStream fciis = new
                // FileCacheImageInputStream(in, null);
                // BufferedImage ii = ImageIO.read(fciis);

                OMRaster image = new OMRaster((int) 0, (int) 0, ii);
                list.add(image);
            } // end if image
        } catch (java.net.MalformedURLException murle) {
            Debug.error("WebImagePlugIn: URL \"" + urlString
                    + "\" is malformed.");
        } catch (java.io.IOException ioe) {
            JOptionPane.showMessageDialog(null,
                    getName() + ":\n\n   Couldn't connect to "
                            + getServerName(),
                    "Connection Problem",
                    JOptionPane.INFORMATION_MESSAGE);

        }

        list.generate(p);
        return list;
    } // end getRectangle

    public abstract String getServerName();

    public java.awt.Component getGUI() {
        JPanel panel = new JPanel(new GridLayout(0, 1));
        JButton parameterButton = new JButton("Adjust Parameters");
        parameterButton.setActionCommand(Layer.DisplayPropertiesCmd);

        if (layer != null) {
            parameterButton.addActionListener(layer);
        }

        JButton viewQueryButton = new JButton("View Current Query");
        viewQueryButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent ae) {
                if (layer != null) {
                    String query = createQueryString(currentProjection);
                    Vector queryStrings = PropUtils.parseMarkers(query, "&");
                    StringBuffer updatedQuery = new StringBuffer();
                    Iterator it = queryStrings.iterator();
                    if (it.hasNext()) {
                        updatedQuery.append((String) it.next());
                    }
                    while (it.hasNext()) {
                        updatedQuery.append("&\n   ");
                        updatedQuery.append((String) it.next());
                    }

                    JOptionPane.showMessageDialog(null,
                            updatedQuery.toString(),
                            "Current Query for " + getName(),
                            JOptionPane.INFORMATION_MESSAGE);
                }
            }
        });

        redrawButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent ae) {
                if (layer != null) {
                    layer.doPrepare();
                }
            }
        });

        redrawButton.setEnabled(layer != null);

        panel.add(parameterButton);
        panel.add(viewQueryButton);
        panel.add(redrawButton);
        return panel;
    }

    protected JButton redrawButton = new JButton("Query Server");
    protected JOptionPane messageWindow = new JOptionPane();

    /**
     * Set the component that this PlugIn uses as a grip to the map.
     */
    public void setComponent(Component comp) {
        super.setComponent(comp);
        if (comp instanceof PlugInLayer) {
            layer = (PlugInLayer) comp;
        } else {
            layer = null;
        }
        redrawButton.setEnabled(layer != null);
    }

} // end WMSPlugin