基于拦截器的ThreadLoacl自动回收器

Z时代
2024-01-10
分类：综合

一、场景

容器t线程池的生命周期和请求的生命周期不同，无法保存请求域的ThreadLocal参数隔离

请求域每次都需要手动回收ThreadLocal，暂时不考自定义线程池的解决

对于simpleDateFormat、DecimalFormat等线程不安全的类，设置作用域，保证线程安全，同时避免重复创建浪费内存空间

二、解决方案

基于拦截器的ThreadLocal回收器

ThreadLocal自动清理注册

HTTP请求的标记

@NoArgsConstructor(access = AccessLevel.PRIVATE)
public class ThreadLocalCleaner {
    private static final List<ThreadLocal<?>> CONTAINER = Lists.newArrayList();
    public static void register(ThreadLocal<?>... threadLocal) {
        if(ArrayUtils.isNotEmpty(threadLocal)) {
            // 可以优化
            CONTAINER.addAll(Arrays.asList(threadLocal));
        }
    }
    public static void clear() {
        CONTAINER.forEach(ThreadLocal::remove);
    }
}


public class ThreadLocalInterceptor extends HandlerInterceptorAdapter {
    /**
     * 是否是从http进入的线程
     */
    private static final ThreadLocal<Boolean> IS_HTTP_REQUEST = new ThreadLocal<>();
    static {
        ThreadLocalCleaner.register(IS_HTTP_REQUEST);
    }
    public static boolean isHttpReqThread() {
        return Boolean.TRUE.equals(IS_HTTP_REQUEST.get());
    }
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //thread local set
        IS_HTTP_REQUEST.set(Boolean.TRUE);
        return super.preHandle(request, response, handler);
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        //thread local remove
        ThreadLocalCleaner.clear();
        super.afterCompletion(request, response, handler, ex);
    }
}