# OpenFeign 异步调用丢失上下文信息
# 1、场景
CompletableFuture<T> future1 = CompletableFuture.supplyAsync(() -> {
return feign.remoteCall();
},executor);
CompletableFuture<T> future2 = CompletableFuture.supplyAsync(() -> {
return feign.remoteCall();
},executor);
CompletableFuture.allOf(future1,future2).join();
.....
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# 2、解决方案-新建拦截器
@Component
@Slf4j
public class FeignRequestInterceptor implements RequestInterceptor
{
@Override
public void apply(RequestTemplate template)
{
HttpServletRequest httpServletRequest = RequestContextUtils.getRequest();
Map<String, String> headers = getHeaders(httpServletRequest);
for (Map.Entry<String, String> entry : headers.entrySet())
{
template.header(entry.getKey(), entry.getValue());
}
}
/**
* 获取原请求头
*/
private Map<String, String> getHeaders(HttpServletRequest request)
{
Map<String, String> map = new LinkedHashMap<>();
Enumeration<String> enumeration = request.getHeaderNames();
if (enumeration != null)
{
while (enumeration.hasMoreElements())
{
String key = enumeration.nextElement();
String value = request.getHeader(key);
if (StrUtil.equals(OAuthConstant.TOKEN_NAME,key))
{
map.put(key, value);
break;
}
}
}
return map;
}
}
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这里将请求头中Token信息放入RequestTemplate的头中，取出请求头中信息用的是RequestContextHolder。
RequestContextHolder中是将请求信息放入ThreadLocal中的，只能取到同一个线程的数据。
因此要解决异步调用的问题，只需要在发起远程调用之前给异步线程添加上主线程的上下文信息
//获取主线程的请求信息
RequestAttributes attributes = RequestContextHolder.getRequestAttributes();
CompletableFuture<T> future1 = CompletableFuture.supplyAsync(() -> {
//将主线程的请求信息设置到异步线程中，否则会丢失请求上下文，导致调用失败
RequestContextHolder.setRequestAttributes(attributes);
//openfeign的调用
return feign.remoteCall();
},executor);
CompletableFuture<T> future2 = CompletableFuture.supplyAsync(() -> {
//将主线程的请求信息设置到异步线程中，否则会丢失请求上下文，导致调用失败
RequestContextHolder.setRequestAttributes(attributes);
//openfeign的调用
return feign.remoteCall();
},executor);
CompletableFuture.allOf(future1,future2).join();
.....
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