DasShape interface wird von Objekten von Java 2D implementiert Arc2D, Area, CubicCurve2D, Ellipse2D, GeneralPath etc..)

Einige der konkreten Objekte sind als @ markieSerializable und können mithilfe der Objektserialisierung gespeichert und wiederhergestellt werden, andere mögen jedochArea Die Schnittstelle nicht implementieren und Fehler auslösen.

Aber da wir ständig gewarnt werden, dass eine solche naive Serialisierung in Java-Implementierungen oder -Versionen nicht unbedingt stabil ist, würde ich lieber irgendeine Form der Serialisierung verwenden.

Das führt uns zum Speichern / Wiederherstellen von XML mitXMLEncoder undXMLDecoder, aber das ist in der Lage, noch weniger von Java 2D zu handhabenShape objects.

Einige Ergebnisse für beide sind unten zu sehen. Wir beginnen mit 6 Shapes und versuchen, diese über Objekt-Serialisierung und Standard-XML-Serialisierung zu speichern / wiederherzustellen.

Wie würden wir alle speichernShape Objekte korrekt über XML?

import java.awt.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.beans.*;
import java.io.*;
import java.util.ArrayList;
import javax.swing.*;
import javax.swing.border.TitledBorder;

public class Serialize2D {

    private JPanel ui;

    Serialize2D() {
        initUI();
    }

    public void initUI() {
        if (ui != null) {
            return;
        }
        ui = new JPanel(new GridLayout(0, 1));

        int[] xpoints = {205, 295, 205, 295};
        int[] ypoints = {5, 25, 25, 45};
        Polygon polygon = new Polygon(xpoints, ypoints, xpoints.length);

        ArrayList<Shape> shapes = new ArrayList<Shape>();
        int w = 45;
        shapes.add(new Rectangle2D.Double(5, 5, 90, 40));
        shapes.add(new Ellipse2D.Double(105, 5, 90, 40));
        shapes.add(polygon);
        shapes.add(new GeneralPath(new Rectangle2D.Double(5, 55, 90, 40)));
        shapes.add(new Path2D.Double(new Rectangle2D.Double(105, 55, 90, 40)));
        shapes.add(new Area(new Rectangle2D.Double(205, 55, 90, 40)));

        addTitledLabelToPanel(shapes, "Original Shapes");
        addTitledLabelToPanel(
                serializeToFromObject(shapes), "Serialize via Object");
        addTitledLabelToPanel(
                serializeToFromXML(shapes), "Serialize via XML");
    }

    public JComponent getUI() {
        return ui;
    }

    public ArrayList<Shape> serializeToFromObject(ArrayList<Shape> shapes) {
        ArrayList<Shape> shps = new ArrayList<Shape>();
        try {
            ObjectOutputStream oos = null;
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            oos = new ObjectOutputStream(baos);
            for (Shape shape : shapes) {
                try {
                    oos.writeObject(shape);
                } catch (Exception ex) {
                    System.err.println(ex.toString());
                }
            }
            oos.flush();
            oos.close();
            System.out.println("length Obj: " + baos.toByteArray().length);
            ByteArrayInputStream bais = new ByteArrayInputStream(
                    baos.toByteArray());
            ObjectInputStream ois = new ObjectInputStream(bais);

            Object o = null;
            try {
                o = ois.readObject();
            } catch (NotSerializableException ex) {
                System.err.println(ex.getMessage());
            } catch (ClassNotFoundException ex) {
                ex.printStackTrace();
            }
            while (o != null) {
                shps.add((Shape) o);
                try {
                    o = ois.readObject();
                } catch (NotSerializableException ex) {
                    System.err.println(ex.getMessage());
                } catch (ClassNotFoundException ex) {
                    ex.printStackTrace();
                }
            }
            return shps;
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        return shps;
    }

    public ArrayList<Shape> serializeToFromXML(ArrayList<Shape> shapes) {
        ArrayList<Shape> shps = new ArrayList<Shape>();
        try {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            XMLEncoder xmle = new XMLEncoder(baos);
            for (Shape shape : shapes) {
                xmle.writeObject(shape);
            }
            xmle.flush();
            xmle.close();

            System.out.println("length XML: " + baos.toByteArray().length);
            ByteArrayInputStream bais
                    = new ByteArrayInputStream(baos.toByteArray());
            XMLDecoder xmld = new XMLDecoder(bais);
            Shape shape = (Shape) xmld.readObject();
            while (shape != null) {
                shps.add(shape);
                try {
                    shape = (Shape) xmld.readObject();
                } catch (ArrayIndexOutOfBoundsException aioobe) {
                    // we've read last object
                    shape = null;
                }
            }
            xmld.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return shps;
    }

    private final static String getType(Object o) {
        String s = o.getClass().getName();
        String[] parts = s.split("\\.");
        s = parts[parts.length - 1].split("\\$")[0];
        return s;
    }

    public static void drawShapesToImage(
            ArrayList<Shape> shapes, BufferedImage image) {
        Graphics2D g = image.createGraphics();
        g.setRenderingHint(
                RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);

        g.setColor(Color.WHITE);
        g.fillRect(0, 0, image.getWidth(), image.getHeight());
        for (Shape shape : shapes) {
            String s = getType(shape);
            g.setColor(Color.GREEN);
            g.fill(shape);
            g.setColor(Color.BLACK);
            g.draw(shape);
            Rectangle r = shape.getBounds();
            int x = r.x + 5;
            int y = r.y + 16;
            if (r.width * r.height != 0) {
                g.drawString(s, x, y);
            }
        }

        g.dispose();
    }

    private void addTitledLabelToPanel(ArrayList<Shape> shapes, String title) {
        int w = 300;
        int h = 100;
        BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        drawShapesToImage(shapes, bi);
        JLabel l = new JLabel(new ImageIcon(bi));
        l.setBorder(new TitledBorder(title));
        ui.add(l);
    }

    public static void main(String[] args) {
        Runnable r = new Runnable() {

            @Override
            public void run() {
                Serialize2D ss = new Serialize2D();
                JOptionPane.showMessageDialog(null, ss.getUI());
            }
        };
        SwingUtilities.invokeLater(r);
    }
}