无法启动Spring启动Web应用程序

Question

I am trying to create a basic application that would use Spring Boot and reactive programming (and without web.xml )

This is my servlet

public class RootServlet extends ServletHttpHandlerAdapter {
    public RootServlet(HttpHandler httpHandler) {
        super(httpHandler);
    }

    public RootServlet() {
        this(WebHttpHandlerBuilder
                .webHandler(toHttpHandler(routingFunction()))
                .build()
        );
    }

    private static RouterFunction<?> routingFunction() {
        return route(GET("/ping"), new PingHandlerFunction());
    }

}

This is my handler function

public class PingHandlerFunction implements HandlerFunction<ServerResponse> {
    @Override
    public Mono<ServerResponse> handle(ServerRequest request) {
        return ok().body(fromObject("true"));
    }
}

And this is my application

@SpringBootApplication
@ComponentScan(basePackages = { "com.lapots.tree.model" })
public class TreeModelApplication extends SpringBootServletInitializer {

    public static void main(String[] args) {
        SpringApplication.run(TreeModelApplication.class, args);
    }

    @Bean
    public ServletRegistrationBean servletRegistrationBean() throws Exception {
        ServletRegistrationBean registrationBean = new ServletRegistrationBean(new RootServlet(), "/");
        registrationBean.setLoadOnStartup(1);
        registrationBean.setAsyncSupported(true);
        return registrationBean;
    }
}

I put properties into resources/application.properties

server.port=8080

logging.level.root=INFO

spring.application.name=tree-model-test

To start web application I use gretty plugin

apply plugin: 'war'
apply plugin: 'org.akhikhl.gretty'

gretty {
    springBoot = true
}

dependencies {
    compile "org.springframework.boot:spring-boot-starter-parent:$springBootVersion"
    compile "org.springframework.boot:spring-boot-starter-web:$springBootVersion"
    compile "org.springframework.boot:spring-boot-starter-webflux:$springBootVersion"

    providedCompile "javax.servlet:javax.servlet-api:$servetApiVersion"
}

Where springBootVersion=2.0.0.BUILD-SNAPSHOT and servletApiVersion=4.0.0-b03

But when I try to start application using gradle jettyRun I get this exception

Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/boot/context/web/SpringBootServletInitializer
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
        at org.eclipse.jetty.webapp.WebAppClassLoader.findClass(WebAppClassLoader.java:510)
        at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:441)
        at org.akhikhl.gretty.FilteringClassLoader.loadClass(FilteringClassLoader.java:62)
        at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:403)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:348)
        at java_lang_Class$forName.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:141)
        at org.akhikhl.gretty.JettyServerConfigurer.createContext(JettyServerConfigurer.groovy:118)
        at org.akhikhl.gretty.JettyServerConfigurer$createContext$0.callCurrent(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:52)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:154)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:190)
        at org.akhikhl.gretty.JettyServerConfigurer.createAndConfigureServer(JettyServerConfigurer.groovy:68)
        at org.akhikhl.gretty.JettyServeurer.createAndConfigureServer(JettyServerConfigurer.groovy)
        at org.akhikhl.gretty.JettyServerConfigurer$createAndConfigureServer.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:117)
        at org.akhikhl.gretty.JettyServerManager.startServer(JettyServerManager.groovy:41)
        at org.akhikhl.gretty.ServerManager$startServer$0.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
        at org.akhikhl.gretty.Runner.run(Runner.groovy:117)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSi
te.java:210)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.call(PogoMetaMethodSite.java:71)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:117)
        at org.akhikhl.gretty.Runner.main(Runner.groovy:44)
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.context.web.SpringBootServletInitializer
        at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at sun.misc.Launcher$AppClassLoader.loadClass(r.java:331)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:450)
        at org.akhikhl.gretty.FilteringClassLoader.loadClass(FilteringClassLoader.java:62)
        at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:403)
        ... 46 more       
Exception in thread "Thread-3" org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdk1.8.0_60\b
in\java.exe'' finished with non-zero exit value 1
        at org.gradle.process.internal.DefaultExecHandle$ExecResultImpl.assertNormalExitValue(DefaultExecHandle.java:366)
        at org.gradle.process.internal.DefaultJavaExecAction.execute(DefaultJavaExecAction.java:31)
        at org.gradle.api.internal.file.DefaultFileOperations.javaexec(DefaultFileOperations.java:159)
        at org.gradle.api.internal.project.AbstractProject.javaexec(AbstractProject.java:784)
        at org.gradle.api.internal.project.AbstractProject.javaexec(AbstractProject.java:780)
        at org.gradle.api.Project$javaexec$6.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
        at org.akhikhl.gretty.DefaultLauncher.javaExec(DefaultLauncher.groovy:89)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:382)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1015)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:49)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:133)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:141)
        at org.akhikhl.gretty.LauncherBase$_launchThread_closure4.doCall(LauncherBase.groovy:256)
        at org.akhikhl.gretty.LauncherBase$_launchThread_closure4.doCall(LauncherBase.groovy)
        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:497)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:292)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1015)
        at groovy.lang.Closure.call(Closure.java:423)
        at groovy.lang.Closure.call(Closure.java:417)
        at groovy.lang.Closure.run(Closure.java:504)
        at java.lang.Thread.run(Thread.java:745)

What is the problem?

Answer 1

After the discussion with @KumareshBabu we found out that in earlier versions of spring boot the class SpringBootServletInitializer was located in org.springframework.boot.context.web while now it is located in org.springframework.boot.web.servlet.support package.

So I decided to use workaround gretty/issue-334

Answer 2

转到http://start.spring.io/并添加依赖项并创建项目，然后在eclipse中导入该项目。