使用 request.getSession() 作为锁定对象? [英] Using request.getSession() as a locking object?

问题描述

我有一些获取和设置会话属性的 Java 代码:

I have some java code that gets and sets a session attribute:

Object obj = session.getAttribute(TEST_ATTR);
if (obj==null) {
  obj = new MyObject();
  session.setAttribute(obj);
}

为了使这段代码线程安全，我想将它包装在一个同步块中.但是我用什么作为锁定对象呢?使用会话有意义吗?

In order to make this code thread-safe, I'd like to wrap it in a synchronized block. But what do I use as the locking object? Does it make sense to use the session?

synchronized (session) {
  Object obj = session.getAttribute(TEST_ATTR);
  if (obj==null) {
    obj = new MyObject();
    session.setAttribute(obj);
  }
}

推荐答案

使用您无法控制的锁通常是不受欢迎的.锁的范围应尽可能紧，因为会话或多或少是一个全局对象，它不符合要求.尝试使用 java.util.concurrent.locks 打包并将其作用于您的类.

It is generally frowned upon to use a lock that you have no control over. A lock should be scoped as tightly as possible and since the session is more or less a global object, it does not fit the bill. Try to use a separate lock from the java.util.concurrent.locks package and scope it to your class.

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