Spring+shiro session与线程池的坑

/**
     * Returns the currently accessible {@code Subject} available to the calling code depending on
     * runtime environment.
     * <p/>
     * This method is provided as a way of obtaining a {@code Subject} without having to resort to
     * implementation-specific methods.  It also allows the Shiro team to change the underlying implementation of
     * this method in the future depending on requirements/updates without affecting your code that uses it.
     *
     * @return the currently accessible {@code Subject} accessible to the calling code.
     * @throws IllegalStateException if no {@link Subject Subject} instance or
     *                               {@link SecurityManager SecurityManager} instance is available with which to obtain
     *                               a {@code Subject}, which which is considered an invalid application configuration
     *                               - a Subject should <em>always</em> be available to the caller.
     */
    public static Subject getSubject() {
        Subject subject = ThreadContext.getSubject();
        if (subject == null) {
            subject = (new Subject.Builder()).buildSubject();
            ThreadContext.bind(subject);
        }
        return subject;
    }