Installation.java

/*
 * Class copied from the Android Developers Blog:
 * http://android-developers.blogspot.com/2011/03/identifying-app-installations.html 
 */
package org.acra.util;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.UUID;

import android.content.Context;

/**
 * <p>
 * Creates a file storing a UUID on the first application start. This UUID can then be used as a identifier of this
 * specific application installation.
 * </p>
 * 
 * <p>
 * This was taken from <a href="http://android-developers.blogspot.com/2011/03/identifying-app-installations.html"> the
 * android developers blog.</a>
 * </p>
 */
public class Installation {
    private static String sID = null;
    private static final String INSTALLATION = "ACRA-INSTALLATION";

    public synchronized static String id(Context context) {
        if (sID == null) {
            File installation = new File(context.getFilesDir(), INSTALLATION);
            try {
                if (!installation.exists())
                    writeInstallationFile(installation);
                sID = readInstallationFile(installation);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
        return sID;
    }

    private static String readInstallationFile(File installation) throws IOException {
        final RandomAccessFile f = new RandomAccessFile(installation, "r");
        byte[] bytes = new byte[(int) f.length()];
        try {
            f.readFully(bytes);
        } finally {
            f.close();
        }
        return new String(bytes);
    }

    private static void writeInstallationFile(File installation) throws IOException {
        final FileOutputStream out = new FileOutputStream(installation);
        try {
            final String id = UUID.randomUUID().toString();
            out.write(id.getBytes());
        } finally {
            out.close();
        }
    }
}