[Java] 详解feign调用session丢失解决方案

@configuration
@enablefeignclients(basepackages = "com.xxx.xxx.client") 
public class feignclientsconfigurationcustom implements requestinterceptor { 
 
 @override
 public void apply(requesttemplate template) { 
 
  requestattributes requestattributes = requestcontextholder.getrequestattributes(); 
  if (requestattributes == null) { 
   return; 
  } 
 
  httpservletrequest request = ((servletrequestattributes) requestattributes).getrequest(); 
  enumeration<string> headernames = request.getheadernames(); 
  if (headernames != null) { 
   while (headernames.hasmoreelements()) { 
  string name = headernames.nextelement(); 
  enumeration<string> values = request.getheaders(name); 
  while (values.hasmoreelements()) { 
   string value = values.nextelement(); 
   template.header(name, value); 
  } 
   } 
  } 
 
 } 
 
}

requestattributes requestattributes = requestcontextholder.getrequestattributes();

hystrix.command.default.execution.isolation.strategy: semaphore

/**
 * abstract class for defining different behavior or implementations for concurrency related aspects of the system with default implementations.
 * <p>
 * for example, every {@link callable} executed by {@link hystrixcommand} will call {@link #wrapcallable(callable)} to give a chance for custom implementations to decorate the {@link callable} with
 * additional behavior.
 * <p>
 * when you implement a concrete {@link hystrixconcurrencystrategy}, you should make the strategy idempotent w.r.t threadlocals.
 * since the usage of threads by hystrix is internal, hystrix does not attempt to apply the strategy in an idempotent way.
 * instead, you should write your strategy to work idempotently. see https://github.com/netflix/hystrix/issues/351 for a more detailed discussion.
 * <p>
 * see {@link hystrixplugins} or the hystrix github wiki for information on configuring plugins: <a
 * href="https://github.com/netflix/hystrix/wiki/plugins" rel="external nofollow" >https://github.com/netflix/hystrix/wiki/plugins</a>.
 */
public abstract class hystrixconcurrencystrategy

public class feignhystrixconcurrencystrategy extends hystrixconcurrencystrategy { 
 
 private static final logger log = loggerfactory.getlogger(feignhystrixconcurrencystrategy.class); 
 private hystrixconcurrencystrategy delegate; 
 
 public feignhystrixconcurrencystrategy() { 
  try { 
   this.delegate = hystrixplugins.getinstance().getconcurrencystrategy(); 
   if (this.delegate instanceof feignhystrixconcurrencystrategy) { 
  // welcome to singleton hell... 
  return; 
   } 
   hystrixcommandexecutionhook commandexecutionhook = 
   hystrixplugins.getinstance().getcommandexecutionhook(); 
   hystrixeventnotifier eventnotifier = hystrixplugins.getinstance().geteventnotifier(); 
   hystrixmetricspublisher metricspublisher = hystrixplugins.getinstance().getmetricspublisher(); 
   hystrixpropertiesstrategy propertiesstrategy = 
   hystrixplugins.getinstance().getpropertiesstrategy(); 
   this.logcurrentstateofhystrixplugins(eventnotifier, metricspublisher, propertiesstrategy); 
   hystrixplugins.reset(); 
   hystrixplugins.getinstance().registerconcurrencystrategy(this); 
   hystrixplugins.getinstance().registercommandexecutionhook(commandexecutionhook); 
   hystrixplugins.getinstance().registereventnotifier(eventnotifier); 
   hystrixplugins.getinstance().registermetricspublisher(metricspublisher); 
   hystrixplugins.getinstance().registerpropertiesstrategy(propertiesstrategy); 
  } catch (exception e) { 
   log.error("failed to register sleuth hystrix concurrency strategy", e); 
  } 
 } 
 
 private void logcurrentstateofhystrixplugins(hystrixeventnotifier eventnotifier, 
   hystrixmetricspublisher metricspublisher, hystrixpropertiesstrategy propertiesstrategy) { 
  if (log.isdebugenabled()) { 
   log.debug("current hystrix plugins configuration is [" + "concurrencystrategy ["
   + this.delegate + "]," + "eventnotifier [" + eventnotifier + "]," + "metricpublisher ["
   + metricspublisher + "]," + "propertiesstrategy [" + propertiesstrategy + "]," + "]"); 
   log.debug("registering sleuth hystrix concurrency strategy."); 
  } 
 } 
 
 @override
 public <t> callable<t> wrapcallable(callable<t> callable) { 
  requestattributes requestattributes = requestcontextholder.getrequestattributes(); 
  return new wrappedcallable<>(callable, requestattributes); 
 } 
 
 @override
 public threadpoolexecutor getthreadpool(hystrixthreadpoolkey threadpoolkey, 
   hystrixproperty<integer> corepoolsize, hystrixproperty<integer> maximumpoolsize, 
   hystrixproperty<integer> keepalivetime, timeunit unit, blockingqueue<runnable> workqueue) { 
  return this.delegate.getthreadpool(threadpoolkey, corepoolsize, maximumpoolsize, keepalivetime, 
  unit, workqueue); 
 } 
 
 @override
 public threadpoolexecutor getthreadpool(hystrixthreadpoolkey threadpoolkey, 
   hystrixthreadpoolproperties threadpoolproperties) { 
  return this.delegate.getthreadpool(threadpoolkey, threadpoolproperties); 
 } 
 
 @override
 public blockingqueue<runnable> getblockingqueue(int maxqueuesize) { 
  return this.delegate.getblockingqueue(maxqueuesize); 
 } 
 
 @override
 public <t> hystrixrequestvariable<t> getrequestvariable(hystrixrequestvariablelifecycle<t> rv) { 
  return this.delegate.getrequestvariable(rv); 
 } 
 
 static class wrappedcallable<t> implements callable<t> { 
  private final callable<t> target; 
  private final requestattributes requestattributes; 
 
  public wrappedcallable(callable<t> target, requestattributes requestattributes) { 
   this.target = target; 
   this.requestattributes = requestattributes; 
  } 
 
  @override
  public t call() throws exception { 
   try { 
  requestcontextholder.setrequestattributes(requestattributes); 
  return target.call(); 
   } finally { 
  requestcontextholder.resetrequestattributes(); 
   } 
  } 
 } 
}

@bean
public feignhystrixconcurrencystrategy feignhystrixconcurrencystrategy() {
 return new feignhystrixconcurrencystrategy();
}