【Spring Cloud】feign调用携带token

码农世界 2024-06-06 后端 80 次浏览 0个评论

当我们再用feign调用的时候，如果对应服务需要token验证则需要我们传递token

网上提供的方法都是添加如下配置:

@Configuration
public class FeignConfig implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate requestTemplate) {
        ServletRequestAttributes attributes = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes());
        if (attributes != null) {
            HttpServletRequest request = attributes.getRequest();
            requestTemplate.header("token", request.getHeader("token"));
        }
    }
}

但是使用这个的时候由于fegin是使用子线程调用的，导致获取到的attributes不存在，所以我们要使用可继承的InheritableThreadLocal来保存

默认如下所示

public class RequestContextListener implements ServletRequestListener {
	private static final String REQUEST_ATTRIBUTES_ATTRIBUTE =
			RequestContextListener.class.getName() + ".REQUEST_ATTRIBUTES";
	@Override
	public void requestInitialized(ServletRequestEvent requestEvent) {
		if (!(requestEvent.getServletRequest() instanceof HttpServletRequest)) {
			throw new IllegalArgumentException(
					"Request is not an HttpServletRequest: " + requestEvent.getServletRequest());
		}
		HttpServletRequest request = (HttpServletRequest) requestEvent.getServletRequest();
		ServletRequestAttributes attributes = new ServletRequestAttributes(request);
		request.setAttribute(REQUEST_ATTRIBUTES_ATTRIBUTE, attributes);
		LocaleContextHolder.setLocale(request.getLocale());
		RequestContextHolder.setRequestAttributes(attributes); // 保存attributes
	}
}
//  RequestContextHolder
/**
 * Bind the given RequestAttributes to the current thread,
 * not exposing it as inheritable for child threads.
 * @param attributes the RequestAttributes to expose
 * @see #setRequestAttributes(RequestAttributes, boolean)
 */
public static void setRequestAttributes(@Nullable RequestAttributes attributes) {
	setRequestAttributes(attributes, false); // inheritable 默认为false
}

所以要使用如下方法重新执行一下

public class MyRequestContextListener implements ServletRequestListener {
    private static final String REQUEST_ATTRIBUTES_ATTRIBUTE =
            MyRequestContextListener.class.getName() + ".REQUEST_ATTRIBUTES";
    /**
     * 初始化
     *
     * @param requestEvent Information about the request
     */
    @Override
    public void requestInitialized(ServletRequestEvent requestEvent) {
        if (!(requestEvent.getServletRequest() instanceof HttpServletRequest)) {
            throw new IllegalArgumentException(
                    "Request is not an HttpServletRequest: " + requestEvent.getServletRequest());
        }
        HttpServletRequest request = (HttpServletRequest) requestEvent.getServletRequest();
        ServletRequestAttributes attributes = new ServletRequestAttributes(request);
        request.setAttribute(REQUEST_ATTRIBUTES_ATTRIBUTE, attributes);
        LocaleContextHolder.setLocale(request.getLocale());
        RequestContextHolder.setRequestAttributes(attributes, true);
    }
	...
}

InheritableThreadLocal也有局限性，即后续父线程数据更改的时候不会在子线程进行同步

tips: InheritableThreadLocal 由于InheritableThreadLocal 是只有在线程初始化的时候才会进行初始化复制，所以后续父线程数据更改的时候不会进行同步,如下所示

private void init(ThreadGroup g, Runnable target, String name,
                      long stackSize, AccessControlContext acc,
                      boolean inheritThreadLocals) {
					  
if (inheritThreadLocals && parent.inheritableThreadLocals != null)
            this.inheritableThreadLocals =
                ThreadLocal.createInheritedMap(parent.inheritableThreadLocals);
			
}
// inheritThreadLocals为True时  构造一个新映射，包括来自给定父映射的所有可继承 ThreadLocal。仅由 createInheritedMap 调用。
private ThreadLocalMap(ThreadLocalMap parentMap) {
	Entry[] parentTable = parentMap.table;
	int len = parentTable.length;
	setThreshold(len);
	table = new Entry[len];
	for (int j = 0; j < len; j++) {
		Entry e = parentTable[j];
		if (e != null) {
			@SuppressWarnings("unchecked")
			ThreadLocal