android NDSDManager onResolveFailed errorCode=3的解决方案

stack overflow有介绍，这个原因可能是系统同时发现了多个

discoveryListener=object:NsdManager.DiscoveryListener{overridefunonServiceFound(service:NsdServiceInfo){onServiceFoundInfo(service)//解析info}....}funonServiceFoundInfo(){//开始解析nsdManager.resolveService(next,object:NsdManager.ResolveListener{overridefunonResolveFailed(serviceInfo:NsdServiceInfo,errorCode:Int){loge(TAG){"Failed to resolve service:${serviceInfo.serviceName}, error:$errorCode"}}overridefunonServiceResolved(serviceInfo:NsdServiceInfo){//解析成功})}

如果你这里直接开始解析，在某些手机上，可能就报错了。告诉你，解析出错，errorCode=3。
因为可能同时有多个onServiceFound过来，同时，resolveService就会出错。

解决办法：串行执行。

这里采用kotlin的suspendCancellableCoroutine + LinkedBlockingQueue解决。

privatevalmResolveQueue=LinkedBlockingQueue<NsdServiceInfo>()privatevalmIsResolving=AtomicBoolean(false)discoveryListener=object:NsdManager.DiscoveryListener{overridefunonServiceFound(service:NsdServiceInfo){onServiceFoundInfo(service)}....}privatefunonServiceFoundInfo(service:NsdServiceInfo){mResolveQueue.offer(service)//内部有锁的processResolveQueue()}privatefunprocessResolveQueue(){if(!mIsResolving.compareAndSet(false,true))returnscope.launch{//子线程while(true){valnext=mResolveQueue.poll()?:breakvalresolved=suspendCancellableCoroutine{cont->try{nsdManager.resolveService(next,object:NsdManager.ResolveListener{overridefunonResolveFailed(serviceInfo:NsdServiceInfo,errorCode:Int){loge(TAG){"Failed to resolve service:${serviceInfo.serviceName}, error:$errorCode"}if(cont.isActive)cont.resume(null)}overridefunonServiceResolved(serviceInfo:NsdServiceInfo){if(cont.isActive)cont.resume(serviceInfo)}})}catch(e:Exception){loge(TAG,e){"Failed to resolve service:${next.serviceName}, error:${e.message}"}if(cont.isActive)(//if(!e.message.isNullOrEmpty()) cont.resumeWithException(e) else cont.resume(null)cont.resume(null)//不做异常抛出)}}if(resolved!=null){handleResolvedService(resolved)//todo 自己的逻辑}}mIsResolving.set(false)if(mResolveQueue.isNotEmpty()){processResolveQueue()}}}