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copied!<p>I have written a SerializableFile class that keeps data in a file. When the object is read, it creates a temporary file. Here it is:</p> <pre><code>public class SerializableFile implements Serializable { private static final File TEMP_DIR = getTempDir(); private transient boolean temporary; private transient String name; private transient File file; public SerializableFile() { } public SerializableFile(File file) { this.file = file; this.name = file.getName(); this.temporary = false; } @Override protected void finalize() throws Throwable { dispose(); super.finalize(); } public void dispose() { if (temporary && file != null) { file.delete(); file = null; } } public File keep(String name) throws IOException { if (temporary) { temporary = false; } else { File newFile = new File(TEMP_DIR, name); keepAs(newFile); file = newFile; } return file; } public void keepAs(File outFile) throws IOException { if ((temporary || file.equals(outFile)) && file.renameTo(outFile)) { temporary = false; file = outFile; } else { InputStream in = new FileInputStream(file); try { OutputStream out = new FileOutputStream(outFile); try { byte buf[] = new byte[4096]; for (int n = in.read(buf); n > 0; n = in.read(buf)) { out.write(buf, 0, n); } } finally { out.close(); } } finally { in.close(); } outFile.setLastModified(file.lastModified()); } } public String getName() { return name; } public File getFile() { return file; } public long lastModified() { return file.lastModified(); } private void writeObject(ObjectOutputStream out) throws IOException { int size = (int)file.length(); long date = file.lastModified(); out.writeUTF(name); out.writeInt(size); out.writeLong(date); InputStream in = new FileInputStream(file); try { byte buf[] = new byte[4096]; while (size > 0) { int n = in.read(buf); if (n <= 0 || n > size) { throw new IOException("Unexpected file size"); } out.write(buf, 0, n); size -= n; } } finally { in.close(); } } private void readObject(ObjectInputStream in) throws IOException { name = in.readUTF(); int size = in.readInt(); long date = in.readLong(); file = File.createTempFile("tmp", ".tmp", TEMP_DIR); OutputStream out = new FileOutputStream(file); try { byte buf[] = new byte[4096]; while (size > 0) { int n = in.read(buf, 0, size <= buf.length ? size : buf.length); if (n <= 0 || n > size) { throw new IOException("Unexpected file size"); } out.write(buf, 0, n); size -= n; } } finally { out.close(); } file.setLastModified(date); temporary = true; } private static File getTempDir() { File dir; String temp = System.getProperty("com.lagalerie.live.temp-dir"); if (temp != null) { dir = new File(temp); } else { String home = System.getProperty("user.home"); dir = new File(home, "temp"); } if (!dir.isDirectory() && !dir.mkdirs()) { throw new RuntimeException("Could not create temp dir " + dir); } return dir; } } </code></pre>

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