PersistenceServiceを使ってJFrameの位置・サイズを記憶
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概要
ServiceManagerからPersistenceServiceを取得し、JFrameなどの位置・サイズの保存、呼び出しを行います。
Screenshot
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サンプルコード
class LoadSaveTask extends SwingWorker<WindowAdapter, Void> {
private final WindowState windowState;
public LoadSaveTask(WindowState windowState) {
super();
this.windowState = windowState;
}
@Override public WindowAdapter doInBackground() {
PersistenceService ps;
BasicService bs;
try {
bs = (BasicService) ServiceManager.lookup("javax.jnlp.BasicService");
ps = (PersistenceService) ServiceManager.lookup("javax.jnlp.PersistenceService");
} catch (UnavailableServiceException use) {
ps = null;
bs = null;
}
if (ps == null || bs == null) {
return null;
} else {
final PersistenceService persistenceService = ps;
final URL codebase = bs.getCodeBase();
loadWindowState(persistenceService, codebase, windowState);
return new WindowAdapter() {
@Override public void windowClosing(WindowEvent e) {
JFrame f = (JFrame) e.getComponent();
if (f.getExtendedState() == Frame.NORMAL) {
windowState.setSize(f.getSize());
windowState.setLocation(f.getLocationOnScreen());
}
saveWindowState(persistenceService, codebase, windowState);
}
};
}
}
private static void loadWindowState(
PersistenceService ps, URL codebase, WindowState windowState) {
try {
FileContents fc = ps.get(codebase);
try (XMLDecoder d = new XMLDecoder(
new BufferedInputStream(fc.getInputStream()))) {
@SuppressWarnings("unchecked")
Map<String, Serializable> map = (Map<String, Serializable>) d.readObject();
windowState.setSize((Dimension) map.get("size"));
windowState.setLocation((Point) map.get("location"));
}
} catch (IOException ex) {
try {
long size = ps.create(codebase, 64000);
System.out.println("Cache created - size: " + size);
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
}
private static void saveWindowState(
PersistenceService ps, URL codebase, WindowState windowState) {
try {
FileContents fc = ps.get(codebase);
try (XMLEncoder e = new XMLEncoder(
new BufferedOutputStream(fc.getOutputStream(true)))) {
HashMap<String, Serializable> map = new HashMap<>();
map.put("size", (Serializable) windowState.getSize());
map.put("location", (Serializable) windowState.getLocation());
e.writeObject(map);
e.flush();
}
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
}
解説
JFrameの位置とサイズをPersistenceServiceで確保したファイルにXMLEncoderで保存、XMLDecoderでそのファイルから値を復元Windows環境ではC:\Users\(user)\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\muffin以下に次のようなmufファイルが作成される
<?xml version="1.0" encoding="UTF-8"?>
<java version="1.7.0_03" class="java.beans.XMLDecoder">
<object class="java.util.HashMap">
<void method="put">
<string>location</string>
<object idref="Point0"/>
</void>
<void method="put">
<string>size</string>
<object idref="Dimension0"/>
</void>
</object>
</java>
XMLEncoderで直接上記のJFrameを書きだす場合、以下のようなIllegalAccessExceptionが発生する
java.lang.IllegalAccessException: Class sun.reflect.misc.Trampoline can not access a member of class MainPanel$2 with modifiers "" Continuing ...
- 回避方法
WindowListenerを実装する匿名内部クラスをpublic class(Java Beans)に変更する- または、
removeWindowListenerで取り除く - または、
XMLEncoder#setExceptionListener(...)で、何もしないExceptionListenerを設定し、警告を捨ててしまう
import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import java.io.*;
import java.nio.charset.StandardCharsets;
import javax.swing.*;
public class MainPanel extends JPanel {
private static final String PROPERTIES_XML = "properties.xml";
public MainPanel() {
super(new BorderLayout());
JTextArea textArea = new JTextArea();
try (Reader fr = new InputStreamReader(
new FileInputStream(PROPERTIES_XML), StandardCharsets.UTF_8)) {
textArea.read(fr, "File");
} catch (Exception ex) {
ex.printStackTrace();
}
add(new JScrollPane(textArea));
}
public static void main(String... args) {
EventQueue.invokeLater(new Runnable() {
@Override public void run() {
createAndShowGUI();
}
});
}
public static void createAndShowGUI() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception e) {
e.printStackTrace();
}
JFrame frame = loadFrame();
frame.setVisible(true);
}
private static JFrame loadFrame() {
JFrame frame = null;
try (XMLDecoder d = new XMLDecoder(new BufferedInputStream(
new FileInputStream(PROPERTIES_XML)))) {
frame = (JFrame) d.readObject();
// d.close();
} catch (Exception ex) {
ex.printStackTrace();
}
if (frame == null) {
frame = new JFrame("title");
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.getContentPane().add(new MainPanel());
frame.setSize(320, 240);
frame.setLocationRelativeTo(null);
}
frame.addWindowListener(new WindowAdapter() {
@Override public void windowClosing(WindowEvent e) {
JFrame frame = (JFrame) e.getComponent();
frame.removeWindowListener(this);
File file = new File(PROPERTIES_XML);
try (XMLEncoder xe = new XMLEncoder(new BufferedOutputStream(
new FileOutputStream(file)))) {
xe.setExceptionListener(new ExceptionListener() {
@Override public void exceptionThrown(Exception exception) {
// XXX:
exception.printStackTrace();
}
});
xe.writeObject(frame);
// xe.flush(); xe.close();
} catch (Exception ex) {
ex.printStackTrace();
}
}
});
return frame;
}
}