@Controller
public class MyController {

    @RequestMapping("/example")
    public String handleRequest(HttpServletRequest request) {
        // 使用request對象
        return "example";
    }
}

HttpServletRequest request = ((ServletRequestAttributes) 
RequestContextHolder.getRequestAttributes()).getRequest();

@GetMapping("/missing-request-header")
public String getMissingRequestHeader() {
    // 主線程獲取請求頭信息
    String mainThreadLanguages = ServletUtils.getLanguagesExistProblem();
    log.info("主線程獲取請求頭信息：{}", mainThreadLanguages);
    new Thread(() -> {
        // 子線程獲取請求頭信息 模擬執(zhí)行耗時操作
        String subThreadLanguages = ServletUtils.getLanguagesExistProblem();
        log.info("子線程獲取請求頭信息：{}", subThreadLanguages);
       
    }).start();
    return "success";
}

    /**
     * 獲取客戶端請求頭中的語言信息。
     * 其會從當(dāng)前的HTTP請求中提取客戶端所設(shè)置的語言信息。
     * 主要通過讀取請求頭中的"X_CLIENT_LANG"字段來獲取客戶端語言偏好。
     *
     * @return String 客戶端請求頭中指定的語言信息。
     * 如果不存在該字段則返回默認的zh-cn。
     */
    public static String  getLanguagesExistProblem() {
        HttpServletRequest request = getRequest();
        Assert.notNull(request);

        String lang =  request.getHeader(X_CLIENT_LANG);

        if (StrUtil.isNotBlank(lang)) {
            return lang;
        }

        return "zh-cn";
    }

public static HttpServletRequest getRequest() {
    HttpServletRequest httpServletRequest = null;
    try {
        RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
        if (requestAttributes instanceof ServletRequestAttributes) {
            ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes) requestAttributes;
            httpServletRequest = servletRequestAttributes.getRequest();
        }
    } catch (Exception e) {
        // 記錄異常，但不向外拋出，以避免可能的業(yè)務(wù)邏輯中斷
        log.error("獲取HttpServletRequest時發(fā)生異常：", e);
    }

    // 返回獲取到的請求對象，如果失敗則返回null
    return httpServletRequest;
}

@Override
protected void service(HttpServletRequest request, 
                        HttpServletResponse response)
        {

      // ... 省略其他無關(guān)代碼
 
     // 處理請求核心代碼，點擊該方法進入
     processRequest(request, response); 
 
}

protected final void processRequest(HttpServletRequest request, 
    // ... 省略其他無關(guān)邏輯
    // 初始化ContextHolders, 便于訪問上下文信息
    initContextHolders(request, localeContext, requestAttributes);
  
    doService(request, response);
  }

private void initContextHolders(HttpServletRequest request,
                                @Nullable LocaleContext localeContext, @Nullable RequestAttributes requestAttributes) {
    // 將參數(shù)localeContext設(shè)置為當(dāng)前線程的LocaleContext，并設(shè)置參數(shù)threadContextInheritable為true，表示上下文對象可以在子線程中繼承
    if (localeContext != null) {
        LocaleContextHolder.setLocaleContext(localeContext, this.threadContextInheritable);
    }
    // 將參數(shù)requestAttributes設(shè)置為當(dāng)前線程的RequestAttributes，并設(shè)置參數(shù)threadContextInheritable為true，表示上下文對象可以在子線程中繼承
    if (requestAttributes != null) {
        RequestContextHolder.setRequestAttributes(requestAttributes, this.threadContextInheritable);
    }
}

public static void setRequestAttributes(@Nullable RequestAttributes attributes, boolean inheritable) {
   if (attributes == null) {
      resetRequestAttributes();
   }
   else {
      if (inheritable) {
         inheritableRequestAttributesHolder.set(attributes);
         requestAttributesHolder.remove();
      }
      else {
         requestAttributesHolder.set(attributes);
         inheritableRequestAttributesHolder.remove();
      }
   }
}