java - Spring Boot，从 websocket 调用 ControllerLinkBuilder.linkTo 时出现 java.lang.IllegalStateException

Question

从 websocket 调用 ControllerLinkBuilder.linkTo 时出现以下错误。

 java.lang.IllegalStateException: Could not find current request via RequestContextHolder
    at org.springframework.util.Assert.state(Assert.java:385)
    at org.springframework.hateoas.mvc.ControllerLinkBuilder.getCurrentRequest(ControllerLinkBuilder.java:234)
    at org.springframework.hateoas.mvc.ControllerLinkBuilder.getBuilder(ControllerLinkBuilder.java:186)
    at org.springframework.hateoas.mvc.ControllerLinkBuilderFactory.linkTo(ControllerLinkBuilderFactory.java:117)
    at org.springframework.hateoas.mvc.ControllerLinkBuilder.linkTo(ControllerLinkBuilder.java:135)
    at urlshortener2014.common.web.UrlShortenerController.createAndSaveIfValid(UrlShortenerController.java:94)
    at urlshortener2014.richcarmine.web.UrlShortenerControllerWithLogs.access$200(UrlShortenerControllerWithLogs.java:45)
    at urlshortener2014.richcarmine.web.UrlShortenerControllerWithLogs$CreateCallable.call(UrlShortenerControllerWithLogs.java:226)
    at urlshortener2014.richcarmine.massiveShortenerNaiveWS.ShortURLWSGenerator.onCall(ShortURLWSGenerator.java:41)
    at urlshortener2014.richcarmine.massiveShortenerNaiveWS.ShortURLWSGenerator.onCall(ShortURLWSGenerator.java:15)
    at urlshortener2014.richcarmine.massiveShortenerREST.RequestContextAwareCallable.call(RequestContextAwareCallable.java:26)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

整个项目都是关于缩短 url，作为我使用 spring websockets 的第一种方法，我试图通过从任何 url 回复缩短的 url 来让它工作。

我的TextWebSocketHandler

public class MyHandler extends TextWebSocketHandler {

    AtomicLong messageOrder = new AtomicLong(0);
    ExecutorService threadPool = Executors.newCachedThreadPool();
    CompletionService<CSVContent> pool = new ExecutorCompletionService<>(threadPool);

    /* controller reference */
    @Autowired
    UrlShortenerControllerWithLogs controller;

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        logger.info("WS: " + message.getPayload());
        long order = messageOrder.getAndIncrement();
        pool.submit(new ShortURLWSGenerator(order,message.getPayload(),"","","",session.getRemoteAddress(),controller));
        CSVContent content = pool.take().get();
        session.sendMessage(new TextMessage("Echo Test: " + content.getShortURL().getUri()));
    }
}

这是ShortURLWSGenerator

public class ShortURLWSGenerator extends RequestContextAwareCallable<CSVContent>{
    ...
    @Override
    public CSVContent onCall() {

        ShortURL shortURL = null;
        try {
            shortURL = controller. new CreateCallable(url,sponsor,brand,owner,address.toString()).call();
        } catch (Exception e) {
            e.printStackTrace();
        }

        CSVContent content = new CSVContent();
        content.setOrder(order);
        content.setShortURL(shortURL);

        return content;
    }
}

二手 RequestContextAwareCallable它在实现与 REST 服务相同的功能时解决了同样的问题，无论如何，即使使用简单的 Callable，我仍然会遇到同样的错误。

这里是 CreateCallable 只是包装了 main 函数

public class CreateCallable implements Callable<ShortURL>{
    ...
    @Override
    public ShortURL call() throws Exception {
        /* explodes while creating the new short url */
        return createAndSaveIfValid(url,sponsor,brand,owner,ip);
    }
}

最后是 createAndSaveIfValid，它调用 ControllerLinkBuilder.linkTo

protected ShortURL createAndSaveIfValid(String url, String sponsor,
        String brand, String owner, String ip) {
    UrlValidator urlValidator = new UrlValidator(new String[] { "http",
            "https" });
    if (urlValidator.isValid(url)) {
        String id = Hashing.murmur3_32()
                .hashString(url, StandardCharsets.UTF_8).toString();
        ShortURL su = new ShortURL(id, url,
                linkTo(
                        methodOn(UrlShortenerController.class).redirectTo(
                                id, null)).toUri(), sponsor, new Date(
                        System.currentTimeMillis()), owner,
                HttpStatus.TEMPORARY_REDIRECT.value(), true, ip, null);
        return shortURLRepository.save(su);
    } else {
        return null;
    }
}

完整工程可见here on github

Answer 1

密切相关的一点是，对于那些单元测试其具体 ResourceAssemblerSupport 实现并体验相同堆栈跟踪的人，以下是模拟它的方法:

@Before
public void setup() {
    HttpServletRequest mockRequest = new MockHttpServletRequest();
    ServletRequestAttributes servletRequestAttributes = new ServletRequestAttributes(mockRequest);
    RequestContextHolder.setRequestAttributes(servletRequestAttributes);
}

@After
public void teardown() {
    RequestContextHolder.resetRequestAttributes();
}