如何将Java 2D Shape对象序列化为XML？
发布时间：2020-08-03 13:22:43 所属栏目：Java 来源：互联网
导读：Shape界面由 Java 2D(Arc2D,Area,CubicCurve2D,Ellipse2D,GeneralPath等)的对象实现. 一些具体对象被标记为Serializable,可以使用对象序列化存储和恢复,但像Area这样的其他对象不会实现接口并抛出错误. 但是由于我们经常被警告,这种天真的序列化在Java实现或
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Shape界面由 Java 2D(Arc2D,Area,CubicCurve2D,Ellipse2D,GeneralPath等)的对象实现. 一些具体对象被标记为Serializable,可以使用对象序列化存储和恢复,但像Area这样的其他对象不会实现接口并抛出错误. 但是由于我们经常被警告,这种天真的序列化在Java实现或版本中不一定稳定,所以我更喜欢使用某种形式的序列化. 这导致我们使用XMLEncoder和XMLDecoder从XML存储/恢复,但是它能够处理更少的Java 2D Shape对象. 两者的一些结果可以在下面看到.我们从6个形状开始,并尝试通过对象序列化和标准XML序列化来存储/恢复它们. 我们将如何通过XML正确存储所有Shape对象？ 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 = {5,25,45};
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(105,40));
shapes.add(polygon);
shapes.add(new GeneralPath(new Rectangle2D.Double(5,55,40)));
shapes.add(new Path2D.Double(new Rectangle2D.Double(105,40)));
shapes.add(new Area(new Rectangle2D.Double(205,40)));
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,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);
}
}
解决方法不幸的是,使用XMLEncoder / Decoder的Shape to XML的天真编码/解码通常会破坏Shape的所有重要信息！所以要做到这一点,仍然使用上面提到的类,我们序列化和恢复正确构造的bean,它们表示从PathIterator获得的形状部分.这些豆是： > PathBean,它存储形成Java-2D Shape形状的PathSegment对象的集合. SerializeShapes GUI 用于演示存储和恢复形状的GUI. >单击椭圆(Ellipse2D),Rectangle(Rectangle2D)或Face(Area)按钮几次. 所选形状将以绿色填充,其他形状将以红色填充. package serialize2d;
import java.awt.*;
import java.awt.event.*;
import java.awt.font.FontRenderContext;
import java.awt.geom.AffineTransform;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Random;
import java.util.Vector;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import javax.swing.event.*;
/** A GUI to make it easy to add/remove shapes from a canvas.
It should persist the shapes between runs. */
public class SerializeShapes {
JPanel ui;
JPanel shapePanel;
Random rand;
JPanel shapeCanvas;
DefaultListModel<Shape> allShapesModel;
ListSelectionModel shapeSelectionModel;
RenderingHints renderingHints;
SerializeShapes() {
initUI();
}
public void initUI() {
if (ui != null) {
return;
}
renderingHints = new RenderingHints(RenderingHints.KEY_DITHERING,RenderingHints.VALUE_DITHER_ENABLE);
renderingHints.put(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
renderingHints.put(RenderingHints.KEY_ALPHA_INTERPOLATION,RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
renderingHints.put(RenderingHints.KEY_COLOR_RENDERING,RenderingHints.VALUE_COLOR_RENDER_QUALITY);
renderingHints.put(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
renderingHints.put(RenderingHints.KEY_STROKE_CONTROL,RenderingHints.VALUE_STROKE_NORMALIZE);
ui = new JPanel(new BorderLayout(4,4));
ui.setBorder(new EmptyBorder(4,4,4));
JPanel controls = new JPanel(new FlowLayout(FlowLayout.CENTER,4));
ui.add(controls,BorderLayout.PAGE_START);
shapeCanvas = new ShapeCanvas();
ui.add(shapeCanvas);
rand = new Random();
allShapesModel = new DefaultListModel<Shape>();
JList<Shape> allShapes = new JList<Shape>(allShapesModel);
allShapes.setCellRenderer(new ShapeListCellRenderer());
shapeSelectionModel = allShapes.getSelectionModel();
shapeSelectionModel.setSelectionMode(
ListSelectionModel.SINGLE_SELECTION);
ListSelectionListener shapesSelectionListener
= new ListSelectionListener() {
@Override
public void valueChanged(ListSelectionEvent e) {
shapeCanvas.repaint();
}
};
allShapes.addListSelectionListener(shapesSelectionListener);
JScrollPane shapesScroll = new JScrollPane(
allShapes,JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,JScrollPane.HORIZONTAL_SCROLLBAR_NEVER
);
// TODO fix this hack..
shapesScroll.getViewport().setPreferredSize(new Dimension(60,200));
ui.add(shapesScroll,BorderLayout.LINE_START);
Action addEllipse = new AbstractAction("Ellipse") {
@Override
public void actionPerformed(ActionEvent e) {
int w = rand.nextInt(100) + 10;
int h = rand.nextInt(100) + 10;
int x = rand.nextInt(shapeCanvas.getWidth() - w);
int y = rand.nextInt(shapeCanvas.getHeight() - h);
Ellipse2D ellipse = new Ellipse2D.Double(x,y,w,h);
addShape(ellipse);
}
};
addEllipse.putValue(Action.MNEMONIC_KEY,KeyEvent.VK_E);
Action addRectangle = new AbstractAction("Rectangle") {
@Override
public void actionPerformed(ActionEvent e) {
int w = rand.nextInt(100) + 10;
int h = rand.nextInt(100) + 10;
int x = rand.nextInt(shapeCanvas.getWidth() - w);
int y = rand.nextInt(shapeCanvas.getHeight() - h);
Rectangle2D rectangle = new Rectangle2D.Double(x,h);
addShape(rectangle);
}
};
addRectangle.putValue(Action.MNEMONIC_KEY,KeyEvent.VK_R);
final int faceStart = 128513;
final int faceEnd = 128528;
final int diff = faceEnd - faceStart;
StringBuilder sb = new StringBuilder();
for (int count = faceStart; count <= faceEnd; count++) {
sb.append(Character.toChars(count));
}
final String s = sb.toString();
Vector<Font> compatibleFontList = new Vector<Font>();
GraphicsEnvironment ge
= GraphicsEnvironment.getLocalGraphicsEnvironment();
Font[] fonts = ge.getAllFonts();
for (Font font : fonts) {
if (font.canDisplayUpTo(s) < 0) {
compatibleFontList.add(font);
}
}
JComboBox fontChooser = new JComboBox(compatibleFontList);
ListCellRenderer fontRenderer = new DefaultListCellRenderer() {
@Override
public Component getListCellRendererComponent(
JList list,Object value,int index,boolean isSelected,boolean cellHasFocus) {
Component c = super.getListCellRendererComponent(
list,value,index,isSelected,cellHasFocus);
JLabel l = (JLabel) c;
Font font = (Font) value;
l.setText(font.getName());
return l;
}
};
fontChooser.setRenderer(fontRenderer);
final ComboBoxModel<Font> fontModel = fontChooser.getModel();
BufferedImage bi = new BufferedImage(1,1,BufferedImage.TYPE_INT_RGB);
Graphics2D g = bi.createGraphics();
final FontRenderContext fontRenderContext = g.getFontRenderContext();
Action addFace = new AbstractAction("Face") {
@Override
public void actionPerformed(ActionEvent e) {
int codepoint = faceStart + rand.nextInt(diff);
String text = new String(Character.toChars(codepoint));
Font font = (Font) fontModel.getSelectedItem();
Area area = new Area(
font.deriveFont(80f).
createGlyphVector(fontRenderContext,text).
getOutline());
Rectangle bounds = area.getBounds();
float x = rand.nextInt(
shapeCanvas.getWidth() - bounds.width) - bounds.x;
float y = rand.nextInt(
shapeCanvas.getHeight() - bounds.height) - bounds.y;
AffineTransform move = AffineTransform.
getTranslateInstance(x,y);
area.transform(move);
addShape(area);
}
};
addFace.putValue(Action.MNEMONIC_KEY,KeyEvent.VK_F);
Action delete = new AbstractAction("Delete") {
@Override
public void actionPerformed(ActionEvent e) {
int idx = shapeSelectionModel.getMinSelectionIndex();
if (idx < 0) {
JOptionPane.showMessageDialog(
ui,"Select a shape to delete","Select a Shape",JOptionPane.ERROR_MESSAGE);
} else {
allShapesModel.removeElementAt(idx);
shapeCanvas.repaint();
}
}
};
delete.putValue(Action.MNEMONIC_KEY,KeyEvent.VK_D);
controls.add(new JButton(addEllipse));
controls.add(new JButton(addRectangle));
controls.add(new JButton(addFace));
controls.add(fontChooser);
controls.add(new JButton(delete));
try {
ArrayList<Shape> shapes = deserializeShapes();
for (Shape shape : shapes) {
allShapesModel.addElement(shape);
}
} catch (Exception ex) {
System.err.println("If first launch,this is as expected!");
ex.printStackTrace();
}
}
private void addShape(Shape shape) {
allShapesModel.addElement(shape);
int size = allShapesModel.getSize() - 1;
shapeSelectionModel.addSelectionInterval(size,size);
}
class ShapeCanvas extends JPanel {
ShapeCanvas() {
setBackground(Color.WHITE);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHints(renderingHints);
Stroke stroke = new BasicStroke(1.5f);
g2.setStroke(stroke);
int idx = shapeSelectionModel.getMinSelectionIndex();
Shape selectedShape = null;
if (idx > -1) {
selectedShape = allShapesModel.get(idx);
}
Enumeration en = allShapesModel.elements();
while (en.hasMoreElements()) {
Shape shape = (Shape) en.nextElement();
if (shape.equals(selectedShape)) {
g2.setColor(new Color(0,255,191));
} else {
g2.setColor(new Color(255,191));
}
g2.fill(shape);
g2.setColor(new Color(0,224));
g2.draw(shape);
}
}
@Override
public Dimension getPreferredSize() {
return new Dimension(500,300);
}
}
public JComponent getUI() {
return ui;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
@Override
public void run() {
SerializeShapes se = new SerializeShapes();
JFrame f = new JFrame("Serialize Shapes");
f.addWindowListener(new SerializeWindowListener(se));
f.setDefaultCloSEOperation(JFrame.DO_NOTHING_ON_CLOSE);
f.setContentPane(se.getUI());
f.setResizable(false);
f.pack();
f.setLocationByPlatform(true);
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
public void serializeShapes() throws FileNotFoundException {
ArrayList<Shape> shapes
= new ArrayList<Shape>();
Enumeration en = allShapesModel.elements();
while (en.hasMoreElements()) {
Shape shape = (Shape) en.nextElement();
shapes.add(shape);
}
ShapeIO.serializeShapes(shapes,this.getClass());
try {
Desktop.getDesktop().open(
ShapeIO.getSerializeFile(this.getClass()));
} catch (Exception e) {
e.printStackTrace();
}
}
public ArrayList<Shape> deserializeShapes() throws FileNotFoundException {
return ShapeIO.deserializeShapes(this.getClass());
}
class ShapeListCellRenderer extends DefaultListCellRenderer {
@Override
public Component getListCellRendererComponent(
JList<? extends Object> list,boolean cellHasFocus) {
Component c = super.getListCellRendererComponent(list,cellHasFocus);
JLabel l = (JLabel) c;
Shape shape = (Shape) value;
ShapeIcon icon = new ShapeIcon(shape,40);
l.setIcon(icon);
l.setText("");
return l;
}
}
class ShapeIcon implements Icon {
Shape shape;
int size;
ShapeIcon(Shape shape,int size) {
this.shape = shape;
this.size = size;
}
@Override
public void paintIcon(Component c,Graphics g,int x,int y) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHints(renderingHints);
Rectangle bounds = shape.getBounds();
int xOff = -bounds.x;
int yOff = -bounds.y;
double xRatio = (double) bounds.width / (double) size;
double yRatio = (double) bounds.height / (double) size;
double ratio = xRatio > yRatio ? xRatio : yRatio;
AffineTransform scale = AffineTransform.getScaleInstance(1 / ratio,1 / ratio);
AffineTransform shift = AffineTransform.getTranslateInstance(xOff,yOff);
AffineTransform totalTransform = new AffineTransform();
totalTransform.concatenate(scale);
totalTransform.concatenate(shift);
Area b = new Area(shape).createTransformedArea(totalTransform);
bounds = b.getBounds();
g2.setColor(Color.BLACK);
g2.fill(b);
}
@Override
public int getIconWidth() {
return size;
}
@Override
public int getIconHeight() {
return size;
}
}
}
class SerializeWindowListener extends WindowAdapter {
SerializeShapes serializeShapes;
SerializeWindowListener(SerializeShapes serializeShapes) {
this.serializeShapes = serializeShapes;
}
@Override
public void windowClosing(WindowEvent e) {
try {
serializeShapes.serializeShapes();
} catch (FileNotFoundException ex) {
ex.printStackTrace();
System.exit(1);
}
System.exit(0);
}
}
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