问静态方法上的Java可重入WriteLock

EN

m_unitLock = new ReentrantReadWriteLock();
m_unitReadLock = m_unitLock.readLock();
m_unitWriteLock = m_unitLock.writeLock()

static List<unit> units = new ArrayList<Unit>();
...
public static addUnit(){
  m_unitWriteLock.lock(); // can not use this inside a static method
  units.add(unit);
  m_unitWriteLock.unlock();
}