我仍然很惊讶netbeans没有这个功能!
import java.io.File;
import org.netbeans.Main;
/**
* Launches Netbeans Rich Client Platform application where mulitple instances of
* the application can run simultaneously for the same user.
* <p>
* Netbeans does not allow to run several instances of an application for the same
* user simultaneously, but this class does the job by fooling Netbeans.
* If an instance is already running then a new folder is created and used for this instance.
* </p>
* <p>
* This is quite tricky and this class is indeed a hack to override Netbeans behaviour.
* An example makes it a little easier to understand, when application is first started
* Netbeans userdir is set from a configuration file like {@code etc/xxxxx.conf} to something like:<br>
* {@code /home/username/.xxxxx/dev/} which includes a lock file.
* <br>
* If application is started again then this lock file is checked and Netbeans tries to connect to the other instance through a socket.
* This class does the trick by never using this folder but instead creating unique directories for each instance like:<br>
* {@code /home/username/.xxxxx/instance_01/netbeans/}<br>
* {@code /home/username/.xxxxx/instance_02/netbeans/}<br>
* {@code /home/username/.xxxxx/instance_03/netbeans/}<br>
* ...
* </p>
*
*/
public class MultipleInstancesMain
{
/** Key for Netbeans default user dir */
private static final String NETBEANS_USER = "netbeans.user";
/** Argument to Netbeans for alternate user dir */
private static final String USERDIR_ARG = "--userdir";
/** Like "C:\Documents and Settings\username\Application Data\.xxxxx" or "/home/username/.xxxxx" */
private static final File MAIN_DIR = getMainDir();
/** Sub dir of MAIN_DIR for each instance of application */
private static final String INSTANCE_DIR = "instance";
/** Sub dir of INSTANCE_DIR where netbeans stores it's settings, logs and cache */
private static final String NETBEANS_SUBDIR = "netbeans";
/** Name of Netbeans lock file inside of NETBEANS_SUBDIR */
private static final String LOCKFILE = "lock";
/** Max number of instance directories we allow */
private static final int MAX_DIR_COUNT = 999;
/** Padding of instance dir */
private static final String PAD = "000";
private static final int PAD_LENGTH = PAD.length();
/**
* Lock file could be present even though application is not running (after crash).
* So we treat it as "dead" after some time, to prevent "dead directories".
*/
private static final long LOCKFILE_MAX_AGE_IN_MILLIS = 1000L * 60L * 60L * 24L * 30L; // 30 days
/**
* Launches application with multiple instances support.
* @param args command line arguments
*/
public static void main(String[] args) throws Exception
{
// Get directory for this instance
String[] userDir = new String[2];
userDir[0] = USERDIR_ARG;
userDir[1] = getNetbeansDir();
// Remove default dir and set this class not to run again
deleteDefaultNetbeansDir();
System.clearProperty("netbeans.mainclass");
// Start Netbeans again with new userdir and default main class
startNetbeans(args, userDir);
}
/**
* Starts Netbeans.
* @param oldArgs command line arguments
* @param newArgs new arguments added
*/
private static void startNetbeans(String[] oldArgs, String[] newArgs) throws Exception
{
String[] args = new String[oldArgs.length + newArgs.length];
for (int i = 0; i <oldArgs.length; i++)
{
args[i] = oldArgs[i];
}
for (int i = 0; i < newArgs.length; i++)
{
args[oldArgs.length + i] = newArgs[i];
}
Main.main(args);
}
/**
* @return the directory that Netbeans will use for this instance of the application
*/
private static String getNetbeansDir()
{
for(int i = 1; i <= MAX_DIR_COUNT; i++)
{
File instanceDir = getSuffixedInstanceDir(i);
if (isLockFileFree(instanceDir))
{
File dirToUse = new File(instanceDir, NETBEANS_SUBDIR);
return dirToUse.getAbsolutePath();
}
}
// This would probably never happen, but we don't want an eternal loop above
String errorMessage = String.format("Unable to find Netbeans userdir, %s dirs checked in '%s'",
MAX_DIR_COUNT, MAIN_DIR.getAbsolutePath());
throw new RuntimeException(errorMessage);
}
private static File getSuffixedInstanceDir(int count)
{
String suffix = PAD + count;
suffix = suffix.substring(suffix.length() - PAD_LENGTH);
File suffixedDir = new File(MAIN_DIR, INSTANCE_DIR + "_" + suffix);
return suffixedDir;
}
/**
* Checks is if Netbeans lock file is free.
* @param instanceDir directory to look for Netbeans directory and lock file in
* @return true if {@code instanceDir} does not have a Netbeans folder with a occupied lock file
*/
private static boolean isLockFileFree(File instanceDir)
{
File netbeansDir = new File(instanceDir, NETBEANS_SUBDIR);
File lockFile = new File(netbeansDir, LOCKFILE);
if (lockFile.exists())
{
return deleteLockFileIfOldEnough(lockFile);
}
else
{
return true;
}
}
/**
* Deletes the lock file if it's old enough.
* @param lockFile lock file to delete
* @return true if it was deleted
* @see #LOCKFILE_MAX_AGE_IN_MILLIS
*/
private static boolean deleteLockFileIfOldEnough(File lockFile)
{
long currentTime = System.currentTimeMillis();
long fileCreated = lockFile.lastModified();
long ageInMillis = currentTime - fileCreated;
if (ageInMillis > LOCKFILE_MAX_AGE_IN_MILLIS)
{
return lockFile.delete();
}
else
{
return false;
}
}
/**
* Netbeans is started with a default userdir, but we need to have a unique dir for each instance.
* Main dir is the directory where directories of all instances are.
* @return main directory in users home area where application settings, logs and cache is stored
*/
private static File getMainDir()
{
String defaultNetbeansDir = System.getProperty(NETBEANS_USER);
File mainDir = new File(defaultNetbeansDir).getParentFile();
return mainDir;
}
/**
* Since we don't use default Netbeans dir at all, we remove it completely.
*/
private static void deleteDefaultNetbeansDir()
{
File defaultNetbeansDir = new File(System.getProperty(NETBEANS_USER));
Thread t = new Thread(new DirectoryDeleter(defaultNetbeansDir), "NetbeansDirDeleter");
t.start();
}
/**
* There are unpredictable behaviour when deleting Netbeans default directory, sometime it succeeds and sometimes not.
* But after some attempts it always succeeds, by deleting it in the background it will eventually be deleted.
* @author username
*/
private static class DirectoryDeleter implements Runnable
{
private static final long SLEEP_TIME = 3000;
private final File dirToDelete;
DirectoryDeleter(File dirToDelete)
{
this.dirToDelete = dirToDelete;
}
/**
* @see java.lang.Runnable#run()
*/
public void run()
{
while(!deleteDirOrFile(dirToDelete))
{
try
{
Thread.sleep(SLEEP_TIME);
}
catch (InterruptedException e)
{
// No idea to do anything here, should never happen anyway...
continue;
}
}
}
/**
* Deletes a file or directory
* @param dirFile directory or file to delete
* @return true if deletion succeeded
*/
private boolean deleteDirOrFile(File dirFile)
{
if (dirFile.isDirectory())
{
for (File f : dirFile.listFiles())
{
boolean deleted = deleteDirOrFile(f);
if (!deleted)
{
return false;
}
}
}
// The directory is now empty so delete it
return dirFile.delete();
}
}
}
