wen Springcloud~openfeign开启hystrix基于线程池熔断的传值问题
我们都知道，在hystrix默认情况下，采用线程池的熔断方式，每个openfeign都有自己的线程，而这使得它无法获取主线程上的变量；现在有个现实的问题就是，当前端登录后，把token经过gateway传到服务A，服务A再调用服务B时，B是无法收到请求头里的token信息的；一种不太好的解决方案就是使用信号量的方式。
使用ThreadLocal存储变量
public class NextHttpHeader {
static final InheritableThreadLocal<Map<String, String>> inheritableThreadLocal = new InheritableThreadLocal<>();
public static void set(String key, String val) {
if (inheritableThreadLocal.get() == null) {
inheritableThreadLocal.set(MapUtils.<String, String>hashMapBuilder(8).put(key, val).build());
} else {
inheritableThreadLocal.get().put(key, val);
}
}
public static String get(String key) {
if (inheritableThreadLocal.get() == null) {
return null;
}
return inheritableThreadLocal.get().get(key);
}
public static Set<String> get() {
if (inheritableThreadLocal.get() == null) {
return null;
}
return inheritableThreadLocal.get().keySet();
}
}
继承HystrixConcurrencyStrategy抽象类，实现自己的赋值逻辑
public class RequestContextHystrixConcurrencyStrategy extends HystrixConcurrencyStrategy {
public <T> Callable<T> wrapCallable(Callable<T> callable) {
// 先包装一下要执行的任务，在这里把ThreadLocal的值取出来
return new ThreadLocalCallable<T>(callable);
}
public static class ThreadLocalCallable<V> implements Callable<V> {
private Callable<V> target;
private Map<String, String> dic = new HashMap<>();
public ThreadLocalCallable(Callable<V> target) {
this.target = target;
NextHttpHeader.get().forEach(o -> {
this.dic.put(o, NextHttpHeader.get(o));
});
}
@Override
public V call() throws Exception {
this.dic.keySet().forEach(o -> {
NextHttpHeader.set(o, this.dic.get(o));
});
return target.call();
}
}
}
注册
@Configuration
@Slf4j
public class HystrixCircuitBreakerConfiguration {
@PostConstruct
public void init() {
HystrixPlugins.getInstance().registerConcurrencyStrategy(new RequestContextHystrixConcurrencyStrategy());
}
}
发现openFeign请求时，将变量放到请求头
/**
* 基于openFeign的拦截器，处理需要向下游传递的信息.
*
* @author lind
* @date 2023/1/29 11:44
* @since 1.0.0
*/
@Configuration
public class FeignTraceIdInterceptor implements RequestInterceptor {
@Override
public void apply(RequestTemplate template) {
if (NextHttpHeader.get() != null) {
NextHttpHeader.get().forEach(o -> {
template.header(o, NextHttpHeader.get(o));
});
}
}
}
spring中的口子太多，太灵活，需要不断的去找那个最优雅，最正确的方法
