NoDeath plugin.

NoDeath.java

public class NoDeath extends JavaPlugin implements Listener {
	
	@Override
	public final void onEnable() {
		Bukkit.getPluginManager().registerEvents(this, this);
	}
	
	@EventHandler
	private final void onEntityDamage(final EntityDamageEvent event) {
		if(event.getEntityType() == EntityType.PLAYER) {
			final Player player = (Player)event.getEntity();
			if(player.hasPermission("nodeath.bealive") && player.getHealth() - event.getDamage() < 1.0) {
				event.setCancelled(true);
				player.setHealth(1.0);
			}
		}
	}

}