我得到ApplicationErrorException: No handler for destination ''试图使用 RSocket 从 android 代码连接到我的 Web 服务器（弹簧启动）。作为一种传输方式，我使用 websockets。
在服务器端我使用：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-rsocket</artifactId>
</dependency>
在客户端我同时使用了：
implementation 'io.rsocket:rsocket-core:1.1.1'
implementation 'io.rsocket:rsocket-transport-netty:1.1.1'
和
implementation 'io.rsocket.kotlin:rsocket-core:0.13.1'
implementation 'io.rsocket.kotlin:rsocket-transport-ktor:0.13.1'
implementation 'io.rsocket.kotlin:rsocket-transport-ktor-client:0.13.1'
implementation "io.ktor:ktor-client-cio:1.6.1"
Ktor 和 Netty 都给了我同样的错误。错误日志如下：
安卓：
ApplicationErrorException (0x201): No handler for destination ''
at io.rsocket.exceptions.Exceptions.from(Exceptions.java:76)
at io.rsocket.core.RSocketRequester.handleFrame(RSocketRequester.java:261)
at io.rsocket.core.RSocketRequester.handleIncomingFrames(RSocketRequester.java:211)
at io.rsocket.core.RSocketRequester.$r8$lambda$kDn7LIfo960b6cXO3SLu8QVkTAE(Unknown Source:0)
at io.rsocket.core.RSocketRequester$$ExternalSyntheticLambda2.accept(Unknown Source:4)
at reactor.core.publisher.LambdaSubscriber.onNext(LambdaSubscriber.java:160)
at io.rsocket.core.ClientServerInputMultiplexer$InternalDuplexConnection.onNext(ClientServerInputMultiplexer.java:248)
at io.rsocket.core.ClientServerInputMultiplexer.onNext(ClientServerInputMultiplexer.java:129)
at io.rsocket.core.ClientServerInputMultiplexer.onNext(ClientServerInputMultiplexer.java:48)
at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:120)
at reactor.netty.channel.FluxReceive.onInboundNext(FluxReceive.java:365)
at reactor.netty.channel.ChannelOperations.onInboundNext(ChannelOperations.java:401)
at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:707)
at reactor.netty.http.client.WebsocketClientOperations.onInboundNext(WebsocketClientOperations.java:161)
at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:94)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:296)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:719)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:655)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:581)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.lang.Thread.run(Thread.java:764)
Suppressed: java.lang.Exception: #block terminated with an error
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:99)
at reactor.core.publisher.Mono.block(Mono.java:1703)
at com.rsockettester.MainActivity$connect$1$1.invokeSuspend(MainActivity.kt:86)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:571)
at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:738)
at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:678)
at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:665)
这是后端使用的控制器代码：
@Controller
class MainController {
@MessageMapping("hello")
fun hello() = "Hello!"
@MessageMapping("name")
fun helloName(name: String) = "Hello, $name!"
}
我用来从 Android 连接的代码'io.rsocket:rsocket-transport-netty:1.1.1'如下：
private fun connect(route: String, message: String): String? = runBlocking {
withContext(Dispatchers.IO) {
val ws: WebsocketClientTransport =
WebsocketClientTransport.create(URI.create(hostUrl))
val clientRSocket = RSocketConnector.connectWith(ws).block()
return@withContext try {
val compositeByteBuf = CompositeByteBuf(ByteBufAllocator.DEFAULT, false, 1);
val routingMetadata = TaggingMetadataCodec.createRoutingMetadata(ByteBufAllocator.DEFAULT, listOf(route))
CompositeMetadataCodec.encodeAndAddMetadata(compositeByteBuf, ByteBufAllocator.DEFAULT,
WellKnownMimeType.MESSAGE_RSOCKET_ROUTING, routingMetadata.content)
val md = ByteBufUtil.getBytes(compositeByteBuf)
val payload = DefaultPayload.create(message.toByteArray(), md)
val s = clientRSocket?.requestResponse(payload)
s?.block()?.dataUtf8
} catch (e: Exception) {
Log.e("net", "RSocket cannot connect: ", e)
e.asString()
} finally {
clientRSocket?.dispose()
}
}
}
private fun connect(route: String, message: String): String? = runBlocking {
val client = HttpClient(CIO) { //create and configure ktor client
install(WebSockets)
install(RSocketSupport) {
connector = RSocketConnector {
connectionConfig {
payloadMimeType = PayloadMimeType(
data = "application/json",
metadata = "application/json"
)
}
acceptor {
RSocketRequestHandler {
requestResponse { it } //echo request payload
}
}
}
}
expectSuccess = false
}
var rSocket: RSocket? = try {
client.rSocket(hostUrl)
} catch (e: Exception) {
Log.e("net", "RSocket cannot connect:", e)
return@runBlocking "RSocket cannot connect: ${e.asString()}"
}
return@runBlocking try {
val payload = Payload(ByteReadPacket(message.toByteArray()),
CompositeMetadata(RoutingMetadata(route)).toPacket())
val response = rSocket?.requestResponse(payload)
Log.d("net", "reached response")
response?.let { it.data.readUTF8Line() }
} catch (e: Exception) {
e.printStackTrace()
"RSocket cannot connect: ${e.asString()}"
}
}
正如我上面提到的，这两种方法都会导致相同的结果：No handler for destination ''
值得一提的是，当我从另一个 Spring Boot 客户端使用相同的路由时，这个问题就不存在了。
有谁知道我做错了什么？如果有人指出我的错误，我会很高兴。提前致谢。
我在 github 上创建了示例项目来帮助重现此错误：rsocket-android-spring
重现步骤：
- 克隆或下载 github 项目rsocket-android-spring
- 运行 Spring Boot 服务器
- 编辑提供 PC 正确 IP 地址的 hostUrl 变量（！）
- 运行 Android 应用程序并单击“发送”按钮
如果您希望在 Android 上从 Netty 切换到 Ktor，您可以使用 MainActivity 代码中的注释方法，但不要忘记使用所需的依赖项build.gradle（存在于那里）。