Java 为什么SpringWebFlux默认选择jetty然后失败？

我正在尝试运行基于SpringBoot2.0.0.M7的应用程序

以下是我在build.gradle中与spring相关的依赖项：

compile "org.springframework.boot:spring-boot-starter-webflux:2.0.0.M7"
compile "org.springframework.boot:spring-boot-starter-data-ldap:2.0.0.M7"
compile "org.springframework.boot:spring-boot-starter-actuator:2.0.0.M7"

根据自动配置报告，是否有可能告诉spring为什么希望默认使用Jetty作为反应引擎（实际上，根据spring文档，reactor Netty是默认引擎）

spring引导自动配置报告（摘录）：

在应用程序启动期间出现的异常：

[0;39morg.springframework.context.ApplicationContextException: Unable to start reactive web server; nested exception is java.lang.NoClassDefFoundError: org/eclipse/jetty/servlet/ServletHolder
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.onRefresh(ReactiveWebServerApplicationContext.java:64)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:49)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:386)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:327)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1245)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1233)
    at com.xyz.abc.routing.web.ApiApplication.main(ApiApplication.java:14)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:50)
    at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51)
Caused by: java.lang.NoClassDefFoundError: org/eclipse/jetty/servlet/ServletHolder
    at org.springframework.boot.web.embedded.jetty.JettyReactiveWebServerFactory.createJettyServer(JettyReactiveWebServerFactory.java:96)
    at org.springframework.boot.web.embedded.jetty.JettyReactiveWebServerFactory.getWebServer(JettyReactiveWebServerFactory.java:87)
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.createWebServer(ReactiveWebServerApplicationContext.java:87)
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.onRefresh(ReactiveWebServerApplicationContext.java:61)
    ... 16 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.eclipse.jetty.servlet.ServletHolder
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:93)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 20 common frames omitted

---

如何让Spring使用reactor netty？

如Marten所述，检查您的依赖项是否与Jetty服务器相关。SpringBoot正在寻找

org.eclipse.jetty.server.server

类作为您选择jetty作为服务器的信号

---

尝试

/gradlew dependencies

并查看该依赖项来自何处。

如果您查看报告，请使用

Netty

匹配的规则。在您的依赖项列表中有一些东西正在添加Jetty。运行

gradle dependencies

查看Jetty中有哪些功能。如果依赖项需要Jetty来实现其自身功能，是否无法告诉spring仍然使用netty？

[0;39morg.springframework.context.ApplicationContextException: Unable to start reactive web server; nested exception is java.lang.NoClassDefFoundError: org/eclipse/jetty/servlet/ServletHolder
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.onRefresh(ReactiveWebServerApplicationContext.java:64)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:49)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:386)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:327)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1245)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1233)
    at com.xyz.abc.routing.web.ApiApplication.main(ApiApplication.java:14)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:50)
    at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51)
Caused by: java.lang.NoClassDefFoundError: org/eclipse/jetty/servlet/ServletHolder
    at org.springframework.boot.web.embedded.jetty.JettyReactiveWebServerFactory.createJettyServer(JettyReactiveWebServerFactory.java:96)
    at org.springframework.boot.web.embedded.jetty.JettyReactiveWebServerFactory.getWebServer(JettyReactiveWebServerFactory.java:87)
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.createWebServer(ReactiveWebServerApplicationContext.java:87)
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.onRefresh(ReactiveWebServerApplicationContext.java:61)
    ... 16 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.eclipse.jetty.servlet.ServletHolder
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:93)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 20 common frames omitted