Spectator with time

Use a bukkitrunnable to remove the player from spectator mode.

 

Set the player's gamemode to Spectator. And use this code:

Code (Text):

              Bukkit.getScheduler().runTaskLater({instance from your class which extends JavaPlugin}, new Runnable()
              {            
                public void run()
                {        
                           // Setting the player's gamemode to survival
p.setGameMode(GameMode.SURVIVAL);
                    }
                }          
              }, 20*{yourseconds}L);
        }