Android设备上的ktor websocket安装错误

Question

我正在尝试在带有 ktor websocket 的 Android 设备上运行简单的聊天示例，但效果不佳。 在 MainActivity 中安装 websocket 服务器时出现错误

这里是 ktor websocket 的 build.gradle

//this is for project
ext.ktor_version = '1.2.5'
maven { url "https://dl.bintray.com/kotlin/ktor" }

//this is for app
 packagingOptions {
        exclude 'META-INF/*'
    }

    implementation "io.ktor:ktor-websockets:$ktor_version"

这是 MainActivity 的代码

import io.ktor.application.*
import io.ktor.features.*
import io.ktor.http.cio.websocket.*
import io.ktor.http.cio.websocket.CloseReason
import io.ktor.http.cio.websocket.Frame
import io.ktor.http.content.*
import io.ktor.routing.*
import io.ktor.sessions.*
import io.ktor.util.*
import io.ktor.websocket.*
import kotlinx.coroutines.channels.*
import java.time.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        install(WebSockets) {
            pingPeriod = Duration.ofSeconds(60) // Disabled (null) by default
            timeout = Duration.ofSeconds(15)
            maxFrameSize = Long.MAX_VALUE // Disabled (max value). The connection will be closed if surpassed this length.
            masking = false
        }
    }
}

当我在 Android Studio 上构建这段代码时，发生了错误

public fun <P : Pipeline<*, ApplicationCall>, B : Any, F : Any> ???.install(feature: ApplicationFeature<???, WebSockets.WebSocketOptions, WebSockets>, configure: WebSockets.WebSocketOptions.() -> Unit = ...): WebSockets defined in io.ktor.application

Answer 1

Websockets 是可以插入应用程序的服务器features 之一，因此install 调用的上下文应该是Ktor 应用程序，而不是Android Activity。我建议您查看Hello world 示例。这是您修改的示例代码：

import io.ktor.application.*
import io.ktor.http.cio.websocket.*
import io.ktor.server.engine.*
import io.ktor.websocket.*
import java.time.Duration
import io.ktor.routing.*
import io.ktor.server.netty.*

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        embeddedServer(Netty, 4444) {
            install(WebSockets) {
                pingPeriod = Duration.ofSeconds(60) // Disabled (null) by default
                timeout = Duration.ofSeconds(15)
                maxFrameSize = Long.MAX_VALUE // Disabled (max value). The connection will be closed if surpassed this length.
                masking = false
            }
            routing {
                webSocket("/") {
                    // ...
                }
            }
        }.start()
    }
}

您需要添加以下依赖项才能使此示例正常工作：

implementation "io.ktor:ktor-server-core:$ktor_version"
implementation "io.ktor:ktor-server-netty:$ktor_version"
implementation "ch.qos.logback:logback-classic:1.2.3" // for logging

Answer 2

能否请您介绍一下您当前使用的 Kotlin 版本和 Gradle 版本？如果 Kotlin 版本小于 1.4，那么我建议尝试将 -jvm 或 -android 添加到 build.gradle 中的 ktor 依赖项名称中。