为什么我的Spring Boot App总是在启动后立即关闭？

Question

这是我的第一个Spring Boot代码。不幸的是，它总是关机。我原本期望它能持续运行，这样我的web客户端就能从浏览器中获取一些数据。

package hello;
import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.*;
import org.springframework.stereotype.*;
import org.springframework.web.bind.annotation.*;

@Controller
@EnableAutoConfiguration
public class SampleController {

    @RequestMapping("/")
    @ResponseBody
    String home() {
        return "Hello World!";
    }

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


[@localhost initial]$ java -jar build/libs/gs-spring-boot-0.1.0.jar

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::            (v1.0.0.RC4)

2014-03-13 09:20:24.805  INFO 14650 --- [           main] hello.SampleController                   : Starting SampleController on localhost.localdomain with PID 14650 (/home/xxx/dev/gs-spring-boot/initial/build/libs/gs-spring-boot-0.1.0.jar started by xxx)
2014-03-13 09:20:25.002  INFO 14650 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@b9eec: startup date [Thu Mar 13 09:20:24 EDT 2014]; root of context hierarchy
2014-03-13 09:20:28.833  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Registering beans for JMX exposure on startup
2014-03-13 09:20:30.148  INFO 14650 --- [           main] o.s.c.support.DefaultLifecycleProcessor  : Starting beans in phase 0
2014-03-13 09:20:30.154  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'requestMappingEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=requestMappingEndpoint]
2014-03-13 09:20:30.316  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'environmentEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=environmentEndpoint]
2014-03-13 09:20:30.335  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'healthEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=healthEndpoint]
2014-03-13 09:20:30.351  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'beansEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=beansEndpoint]
2014-03-13 09:20:30.376  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'infoEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=infoEndpoint]
2014-03-13 09:20:30.400  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'metricsEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=metricsEndpoint]
2014-03-13 09:20:30.413  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'traceEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=traceEndpoint]
2014-03-13 09:20:30.428  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'dumpEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=dumpEndpoint]
2014-03-13 09:20:30.450  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'autoConfigurationAuditEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=autoConfigurationAuditEndpoint]
2014-03-13 09:20:30.465  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'shutdownEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=shutdownEndpoint]
2014-03-13 09:20:30.548  INFO 14650 --- [           main] o.s.b.a.e.jmx.EndpointMBeanExporter      : Located managed bean 'configurationPropertiesReportEndpoint': registering with JMX server as MBean [org.springframework.boot:type=Endpoint,name=configurationPropertiesReportEndpoint]
2014-03-13 09:20:30.589  INFO 14650 --- [           main] hello.SampleController                   : Started SampleController in 7.396 seconds (JVM running for 9.569)
2014-03-13 09:20:30.608  INFO 14650 --- [       Thread-2] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@b9eec: startup date [Thu Mar 13 09:20:24 EDT 2014]; root of context hierarchy
2014-03-13 09:20:30.610  INFO 14650 --- [       Thread-2] o.s.c.support.DefaultLifecycleProcessor  : Stopping beans in phase 0
2014-03-13 09:20:30.624  INFO 14650 --- [       Thread-2] o.s.b.a.e.jmx.EndpointMBeanExporter      : Unregistering JMX-exposed beans on shutdown

附注。Build.Gradle是错误。

dependencies {
    // tag::jetty[]
    compile("org.springframework.boot:spring-boot-starter-web") {
        **exclude module: "spring-boot-starter-tomcat"**
    }

一旦我用粗体取下上面那一行，一切都正常了。我的应用程序上下文现在是正确的。谢谢戴夫

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::            (v1.0.0.RC4)

2014-03-13 13:58:08.965  INFO 7307 --- [           main] hello.Application                        : Starting
 Application on  with PID 7307 (/ladev/home/xxx/dev/gs-spring-boot/initial/build/libs/gs-spring-boo
t-0.1.0.jar started by xxx)
2014-03-13 13:58:09.021  INFO 7307 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshi
ng org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@45490eb5: startup
 date [Thu Mar 13 13:58:09 MDT 2014]; root of context hierarchy
2014-03-13 13:58:09.653  INFO 7307 --- [           main] o.s.b.f.s.DefaultListableBeanFactory     : Overridi
ng bean definition for bean 'beanNameViewResolver': replacing [Root bean: class [null]; scope=; abstract=fal
se; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanNam
e=org.springframework.boot.actuate.autoconfigure.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration;
 factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class
 path resource [org/springframework/boot/actuate/autoconfigure/ErrorMvcAutoConfiguration$WhitelabelErrorView
Configuration.class]] with [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3;
 dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconf
igure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter; factoryMethodName=beanNameViewResolver; in
itMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/au
toconfigure/web/WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.class]]

Answer 1

解决方法：该应用程序不是webapp，因为它在类路径上没有嵌入式容器（例如，Tomcat）。加一个就解决了。如果您使用的是Maven，那么在pom.xml中添加以下内容：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

对于Gradle(build.Gradle)，它看起来像

dependencies {
    compile 'org.springframework.boot:spring-boot-starter-web'
}