日常分享 - 非web请求使用新线程执行报错

报错内容：No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.

我这边的场景是：消费到一条mq的新消息，然后执行业务；业务中包含有一个异步操作，这个异步操作使用了线程池，在使用线程池进行执行的时候报了这个错误

下面贴出代码，每次使用线程池执行的时候都会用访问方法decorate，获取请求的上下文，但是本次的请求不是一个web请求，是没有这个上下文的信息，所以这里报错

@Slf4j
public class ThreadPoolConfig {

    /**
     * 获取当前机器CPU数量
     */
    private static final int cpu = Runtime.getRuntime().availableProcessors();
    /**
     * 核心线程数（默认线程数）
     */
    private static final int corePoolSize = cpu;
    /**
     * 最大线程数
     */
    private static final int maxPoolSize = cpu * 2;
    /**
     * 允许线程空闲时间（单位：默认为秒）
     */
    private static final int keepAliveTime = 60;

    /**
     * 缓冲队列数
     */
    private static final int queueCapacity = 200;
    /**
     * 线程池名前缀
     */
    private static final String threadNamePrefix = "xxx-threadPool-";


    @Bean("poolTaskExecutor")
    @Primary
    public ThreadPoolTaskExecutor taskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        //传递异步调用上下文
        executor.setTaskDecorator(new ContextDecorator());
        executor.setCorePoolSize(corePoolSize);
        executor.setMaxPoolSize(maxPoolSize);
        executor.setQueueCapacity(queueCapacity);
        executor.setKeepAliveSeconds(keepAliveTime);
        executor.setThreadNamePrefix(threadNamePrefix);
        // 线程池对拒绝任务的处理策略
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        //设置在关闭线程池时是否等待任务完成
        executor.setWaitForTasksToCompleteOnShutdown(true);
        // 初始化
        executor.initialize();
        return executor;

    }

    class ContextDecorator implements TaskDecorator {
        @Override
        public Runnable decorate(Runnable runnable) {
            RequestAttributes context = RequestContextHolder.currentRequestAttributes();
            return () -> {
                try {
                    ServletRequestAttributes attributes = (ServletRequestAttributes) context;
                        HttpServletRequest request = attributes.getRequest();
                        Map<String, String> headers = new ConcurrentHashMap<>();
                        Enumeration<String> headerNames = request.getHeaderNames();
                        if (headerNames != null) {
                            while (headerNames.hasMoreElements()) {
                                String name = headerNames.nextElement();
                                String values = request.getHeader(name);
                                headers.put(name, values);
                            }
                        }
                        ThreadLocalUtil.set("thread header", headers);
                    RequestContextHolder.setRequestAttributes(context);
                    runnable.run();
                } finally {
                    RequestContextHolder.resetRequestAttributes();
                }
            };
        }
    }
}

解决的代码见下面代码，内部类ContextDecorator获取上下文的地方做一个修改，

class ContextDecorator implements TaskDecorator {
        @Override
        public Runnable decorate(Runnable runnable) {
            RequestAttributes context = getRequestAttributesSafely();
            return () -> {
                try {
                    if (context instanceof ServletRequestAttributes){
                        ServletRequestAttributes attributes = (ServletRequestAttributes) context;
                        HttpServletRequest request = attributes.getRequest();
                        Map<String, String> headers = new ConcurrentHashMap<>();
                        Enumeration<String> headerNames = request.getHeaderNames();
                        if (headerNames != null) {
                            while (headerNames.hasMoreElements()) {
                                String name = headerNames.nextElement();
                                String values = request.getHeader(name);
                                headers.put(name, values);
                            }
                        }
                        ThreadLocalUtil.set("thread header", headers);
                    }
                    RequestContextHolder.setRequestAttributes(context);
                    runnable.run();
                } finally {
                    RequestContextHolder.resetRequestAttributes();
                }
            };
        }

        private RequestAttributes getRequestAttributesSafely(){
            RequestAttributes requestAttributes = null;
            try{
                requestAttributes = RequestContextHolder.currentRequestAttributes();
            }catch (IllegalStateException e){
                requestAttributes = new NoWebRequestAttributes();
            }
            return requestAttributes;
        }
    }

NoWebRequestAttributes类

public class NoWebRequestAttributes implements RequestAttributes {
    @Override
    public Object getAttribute(String s, int i) {
        return null;
    }

    @Override
    public void setAttribute(String s, Object o, int i) {

    }

    @Override
    public void removeAttribute(String s, int i) {

    }

    @Override
    public String[] getAttributeNames(int i) {
        return new String[0];
    }

    @Override
    public void registerDestructionCallback(String s, Runnable runnable, int i) {

    }

    @Override
    public Object resolveReference(String s) {
        return null;
    }

    @Override
    public String getSessionId() {
        return null;
    }

    @Override
    public Object getSessionMutex() {
        return null;
    }
}