Gradle + Spring Boot + Jetty + JSP 失败

Question

我正在尝试将spring-boot 与gradle 构建系统和jetty 一起使用。现在jsp没有渲染，我得到这个错误消息

Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Sun Jul 17 00:31:05 CEST 2016
There was an unexpected error (type=Internal Server Error, status=500).
org.springframework.web.util.NestedServletException: Handler processing failed; nested exception is java.lang.NoClassDefFoundError: org/apache/jasper/runtime/JspSourceImports

它似乎依赖于 build.gradle 文件。

 buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath "org.springframework.boot:spring-boot-gradle-plugin:1.3.6.RELEASE"
        classpath 'org.springframework:springloaded:1.2.5.RELEASE'
    }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'idea'
apply plugin: 'spring-boot'
apply plugin: 'rebel'

buildscript {
    repositories {
        mavenCentral()
    }

    dependencies {
        classpath group: 'org.zeroturnaround', name: 'gradle-jrebel-plugin', version: '1.1.3'
    }
}
jar {
    baseName = 'gs-spring-boot'
    version =  '0.1.0'
}

repositories {
    mavenCentral()
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

dependencies {
    // tag::jetty[]
    compile("org.springframework.boot:spring-boot-starter-web") {
        exclude module: "spring-boot-starter-tomcat"
    }
    compile("org.springframework.boot:spring-boot-starter-jetty")
    // end::jetty[]
    // tag::actuator[]
    compile("org.springframework.boot:spring-boot-starter-actuator")
    compile("javax.servlet:javax.servlet-api")
    compile('org.eclipse.jetty:jetty-webapp')
    compile('org.eclipse.jetty:jetty-jsp')

    runtime 'javax.servlet:javax.servlet-api'
    runtime 'javax.servlet:jstl'

    testCompile("org.springframework.boot:spring-boot-starter-test")

    testCompile("junit:junit")

}

// change default IntelliJ output directory for compiling classes
idea {
    module {
        inheritOutputDirs = false
        outputDir = file("$buildDir/classes/main/")
    }
}

task wrapper(type: Wrapper) {
    gradleVersion = '2.3'
}

如果我使用 maven，那么如果我从命令行使用 mvn jetty:run 启动它，我可以渲染 jsp

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <!-- Your own application should inherit from spring-boot-starter-parent -->
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-samples</artifactId>
        <version>1.4.0.BUILD-SNAPSHOT</version>
    </parent>
    <artifactId>spring-boot-sample-jetty-jsp</artifactId>
    <packaging>war</packaging>
    <name>Spring Boot Jetty JSP Sample</name>
    <description>Spring Boot Jetty JSP Sample</description>
    <url>http://projects.spring.io/spring-boot/</url>
    <organization>
        <name>Pivotal Software, Inc.</name>
        <url>http://www.spring.io</url>
    </organization>
    <properties>
        <main.basedir>${basedir}/../..</main.basedir>
        <m2eclipse.wtp.contextRoot>/</m2eclipse.wtp.contextRoot>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.apache.tomcat.embed</groupId>
                    <artifactId>tomcat-embed-el</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jetty</artifactId>
            <!--<scope>provided</scope>-->
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>
        <dependency>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>apache-jsp</artifactId>
            <!--<scope>provided</scope>-->
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <executable>true</executable>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <useSystemClassLoader>false</useSystemClassLoader>
                </configuration>
            </plugin>



        </plugins>
    </build>
</project>

为什么还要将构建系统与运行时混合在一起，为什么我必须手动组合一个码头服务器来运行一些 jsp 和 servlet？我不明白为什么 Java 项目必须使简单的事情变得不可能。以前用jsp和servlet很容易，现在想用jsp，几天就遇到2个问题。

这种类型的任务甚至没有一个使用 gradle 的工作示例吗？你知道我想要做什么吗？

用 Jetty 查看 JSP 应该是最基本的事情，为什么我要用 Java 服务器来实现其他东西呢？没有人将 Jetty 仅用于静态内容或仅用于 RestAPI - Jetty 的主要功能是查看 JSP，那么为什么让简单的任务变得不可能呢？

我也用python做web开发，用python这种类型的问题是不可理解的——查看模板就可以了，即使我们尝试了也无法解决这种类型的问题。现在，Java 浪费了我整个周末的时间，因为指令错误或没有指令、错误的构建文件和不完整的项目。我希望我留在 C、汇编和 python。至少我们可以在那里调试东西并且我们有替代方案。每次我尝试用 Java 做一些事情时，我们都会遇到这个问题，一堆令人困惑的堆栈跟踪，你必须链接到最模糊的 4 GB jar 和 xml 地狱。我将回到汇编编程，在那里可以知道你在做什么，而且你不需要 4 GB 的 XML 来运行一个只会造成混乱的服务器。

org.springframework.web.util.NestedServletException: Handler processing failed; nested exception is java.lang.NoClassDefFoundError: org/apache/jasper/runtime/JspSourceImports
        at org.springframework.web.servlet.DispatcherServlet.triggerAfterCompletionWithError(DispatcherServlet.java:1305) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:979) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:858) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:687) ~[javax.servlet-api-3.1.0.jar:3.1.0]
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) ~[javax.servlet-api-3.1.0.jar:3.1.0]
        at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:812) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1669) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:224) ~[websocket-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:281) ~[spring-boot-actuator-1.3.6.RELEASE.jar:1.3.6.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:115) ~[spring-boot-actuator-1.3.6.RELEASE.jar:1.3.6.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) ~[spring-boot-actuator-1.3.6.RELEASE.jar:1.3.6.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:585) [jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577) [jetty-security-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515) [jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1061) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.Server.handle(Server.java:499) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:311) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:257) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:544) [jetty-io-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635) [jetty-util-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555) [jetty-util-9.2.17.v20160517.jar:9.2.17.v20160517]
        at java.lang.Thread.run(Thread.java:745) [na:1.8.0_91]
Caused by: java.lang.NoClassDefFoundError: org/apache/jasper/runtime/JspSourceImports
        at java.lang.ClassLoader.defineClass1(Native Method) ~[na:1.8.0_91]
        at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[na:1.8.0_91]
        at java.lang.ClassLoader.defineClass(ClassLoader.java:642) ~[na:1.8.0_91]
        at org.apache.jasper.servlet.JasperLoader.findClass(JasperLoader.java:232) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        at org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:193) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        at org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:125) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        at org.apache.jasper.JspCompilationContext.load(JspCompilationContext.java:656) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        at org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:202) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:473) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:377) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) ~[javax.servlet-api-3.1.0.jar:3.1.0]
        at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:812) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1669) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:585) [jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:595) [jetty-security-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515) [jetty-servlet-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1061) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) [jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.Dispatcher.forward(Dispatcher.java:191) ~[jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.eclipse.jetty.server.Dispatcher.forward(Dispatcher.java:72) ~[jetty-server-9.2.17.v20160517.jar:9.2.17.v20160517]
        at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1246) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1029) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:973) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
        ... 48 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.apache.jasper.runtime.JspSourceImports
        at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_91]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_91]
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) ~[na:1.8.0_91]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_91]
        at org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:187) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        at org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:125) ~[javax.servlet.jsp-2.3.2.jar:2.3.2]
        ... 92 common frames omitted

我的文件结构是

dac@dac-Latitude-E7450 ~/p/s/s/spring-boot-sample-jetty-jsp> tree
.
├── build
│   ├── classes
│   │   ├── main
│   │   │   ├── application.properties
│   │   │   ├── rebel.xml
│   │   │   └── sample
│   │   │       └── jetty
│   │   │           └── jsp
│   │   │               ├── MyException.class
│   │   │               ├── MyRestResponse.class
│   │   │               ├── SampleJettyJspApplication.class
│   │   │               └── WelcomeController.class
│   │   └── test
│   ├── dependency-cache
│   ├── libs
│   │   ├── gs-spring-boot-0.1.0.jar
│   │   └── gs-spring-boot-0.1.0.jar.original
│   ├── resources
│   │   └── main
│   │       ├── application.properties
│   │       └── rebel.xml
│   └── tmp
│       ├── compileJava
│       │   └── emptySourcePathRef
│       ├── compileTestJava
│       │   └── emptySourcePathRef
│       └── jar
│           └── MANIFEST.MF
├── build.gradle
├── build.log
├── classes
│   └── production
│       └── spring-boot-sample-jetty-jsp
│           ├── application.properties
│           └── rebel.xml
├── gradle
│   └── wrapper
│       ├── gradle-wrapper.jar
│       └── gradle-wrapper.properties
├── gradlew
├── gradlew.bat
├── pom.xml
├── spring
│   ├── gradle
│   │   └── wrapper
│   │       ├── gradle-wrapper.jar
│   │       └── gradle-wrapper.properties
│   ├── gradlew
│   ├── gradlew.bat
│   ├── pom.xml
│   └── src
│       ├── main
│       │   ├── java
│       │   │   └── sample
│       │   │       └── jetty
│       │   │           └── jsp
│       │   │               ├── MyException.java
│       │   │               ├── MyRestResponse.java
│       │   │               ├── SampleJettyJspApplication.java
│       │   │               └── WelcomeController.java
│       │   ├── resources
│       │   │   ├── application.properties
│       │   │   └── rebel.xml
│       │   └── webapp
│       │       └── WEB-INF
│       │           └── jsp
│       │               └── welcome.jsp
│       └── test
│           └── java
│               └── sample
│                   └── jetty
│                       └── jsp
│                           └── SampleWebJspApplicationTests.java
├── spring-boot-sample-jetty-jsp.iml
├── spring-boot-sample-jetty-jsp.ipr
├── spring-boot-sample-jetty-jsp.iws
├── src
│   ├── main
│   │   ├── java
│   │   │   └── sample
│   │   │       └── jetty
│   │   │           └── jsp
│   │   │               ├── MyException.java
│   │   │               ├── MyRestResponse.java
│   │   │               ├── SampleJettyJspApplication.java
│   │   │               └── WelcomeController.java
│   │   ├── resources
│   │   │   ├── application.properties
│   │   │   └── rebel.xml
│   │   └── webapp
│   │       └── WEB-INF
│   │           └── jsp
│   │               └── welcome.jsp
│   └── test
│       └── java
│           └── sample
│               └── jetty
│                   └── jsp
│                       └── SampleWebJspApplicationTests.java
└── target
    ├── classes
    │   ├── application.properties
    │   ├── rebel.xml
    │   └── sample
    │       └── jetty
    │           └── jsp
    │               ├── MyException.class
    │               ├── MyRestResponse.class
    │               ├── SampleJettyJspApplication.class
    │               └── WelcomeController.class
    ├── generated-sources
    │   └── annotations
    ├── generated-test-sources
    │   └── test-annotations
    ├── maven-archiver
    │   └── pom.properties
    ├── maven-status
    │   └── maven-compiler-plugin
    │       ├── compile
    │       │   └── default-compile
    │       │       ├── createdFiles.lst
    │       │       └── inputFiles.lst
    │       └── testCompile
    │           └── default-testCompile
    │               ├── createdFiles.lst
    │               └── inputFiles.lst
    ├── spring-boot-sample-jetty-jsp-1.4.0.BUILD-SNAPSHOT
    │   ├── META-INF
    │   └── WEB-INF
    │       ├── classes
    │       │   ├── application.properties
    │       │   ├── rebel.xml
    │       │   └── sample
    │       │       └── jetty
    │       │           └── jsp
    │       │               ├── MyException.class
    │       │               ├── MyRestResponse.class
    │       │               ├── SampleJettyJspApplication.class
    │       │               └── WelcomeController.class
    │       ├── jsp
    │       │   └── welcome.jsp
    │       └── lib
    │           ├── classmate-1.3.1.jar
    │           ├── hibernate-validator-5.2.4.Final.jar
    │           ├── jackson-annotations-2.8.0.jar
    │           ├── jackson-core-2.8.0.jar
    │           ├── jackson-databind-2.8.0.jar
    │           ├── jboss-logging-3.3.0.Final.jar
    │           ├── jcl-over-slf4j-1.7.21.jar
    │           ├── jstl-1.2.jar
    │           ├── jul-to-slf4j-1.7.21.jar
    │           ├── log4j-over-slf4j-1.7.21.jar
    │           ├── logback-classic-1.1.7.jar
    │           ├── logback-core-1.1.7.jar
    │           ├── slf4j-api-1.7.21.jar
    │           ├── snakeyaml-1.17.jar
    │           ├── spring-aop-4.3.2.BUILD-SNAPSHOT.jar
    │           ├── spring-beans-4.3.2.BUILD-SNAPSHOT.jar
    │           ├── spring-boot-1.4.0.BUILD-SNAPSHOT.jar
    │           ├── spring-boot-autoconfigure-1.4.0.BUILD-SNAPSHOT.jar
    │           ├── spring-boot-starter-1.4.0.BUILD-SNAPSHOT.jar
    │           ├── spring-boot-starter-logging-1.4.0.BUILD-SNAPSHOT.jar
    │           ├── spring-boot-starter-validation-1.4.0.BUILD-SNAPSHOT.jar
    │           ├── spring-boot-starter-web-1.4.0.BUILD-SNAPSHOT.jar
    │           ├── spring-context-4.3.2.BUILD-SNAPSHOT.jar
    │           ├── spring-core-4.3.2.BUILD-SNAPSHOT.jar
    │           ├── spring-expression-4.3.2.BUILD-SNAPSHOT.jar
    │           ├── spring-web-4.3.2.BUILD-SNAPSHOT.jar
    │           ├── spring-webmvc-4.3.2.BUILD-SNAPSHOT.jar
    │           └── validation-api-1.1.0.Final.jar
    ├── spring-boot-sample-jetty-jsp-1.4.0.BUILD-SNAPSHOT.war
    ├── spring-boot-sample-jetty-jsp-1.4.0.BUILD-SNAPSHOT.war.original
    ├── surefire-reports
    │   ├── sample.jetty.jsp.SampleWebJspApplicationTests.txt
    │   └── TEST-sample.jetty.jsp.SampleWebJspApplicationTests.xml
    └── test-classes
        └── sample
            └── jetty
                └── jsp
                    └── SampleWebJspApplicationTests.class

85 directories, 95 files

Answer 1

首先，您遇到的问题不是 Java 问题，而是 Spring Boot 问题。 Spring Boot 是一个自以为是的约定优于配置的框架，它来自 Spring，它应该让你的生活更轻松......如果你知道你在用它做什么，大多数没有 Spring 经验的人真的不知道（完全可以理解，我必须补充）。

Spring Boot 所做的是扫描您的类路径，查看您的项目中有哪些依赖项，查看您提供了哪些手动配置，然后决定自动包含哪些其他配置选项。

为什么必须让 Maven 参与运行您的应用程序？好吧，仅仅因为您将打包声明为 war，这告诉 Spring Boot 您希望能够将文件部署到 Web 服务器，而不是使用嵌入式 Jetty 运行它。 mvn jetty:run 正是这样做的——它启动了一个 Jetty 服务器并将你的应用程序部署到它上面。您可以在现有的 Jetty 上手动执行此操作，但出于开发目的，这种方式要快得多。

就您手头的问题而言，这是一个known issue，并且仍然无法将 JAR 打包 - 而且您的 Gradle 脚本正在使用 JAR 打包 - 对于想要执行 JSP 模板的 Spring Boot 应用程序。 （不过，我建议使用Thymeleaf）。

但如果你还想做 Gradle + Jetty + JSP，请make sure you set your packaging to war