继续学习Spring Boot，我新建了一个Spring Boot的项目 ，建好项目之后，进行测试时，出现了如下错误：
java.net.BindException: Address already in use: bind
at sun.nio.ch.Net.bind0(Native Method) ~[na:1.8.0_77]
at sun.nio.ch.Net.bind(Net.java:433) ~[na:1.8.0_77]
at sun.nio.ch.Net.bind(Net.java:425) ~[na:1.8.0_77]
at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223) ~[na:1.8.0_77]
at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74) ~[na:1.8.0_77]
at org.apache.tomcat.util.net.NioEndpoint.bind(NioEndpoint.java:210) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.tomcat.util.net.AbstractEndpoint.start(AbstractEndpoint.java:978) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.coyote.AbstractProtocol.start(AbstractProtocol.java:628) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.catalina.connector.Connector.startInternal(Connector.java:1022) [tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) [tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.catalina.core.StandardService.addConnector(StandardService.java:225) [tomcat-embed-core-8.5.15.jar:8.5.15]
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.addPreviouslyRemovedConnectors(TomcatEmbeddedServletContainer.java:247) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.start(TomcatEmbeddedServletContainer.java:190) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.startEmbeddedServletContainer(EmbeddedWebApplicationContext.java:297) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.finishRefresh(EmbeddedWebApplicationContext.java:145) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546) [spring-context-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:762) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:372) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1187) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1176) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at com.gl.demo2.Demo2Application.main(Demo2Application.java:10) [classes/:na]
2018-01-31 21:58:49.596 ERROR 14148 --- [ main] o.apache.catalina.core.StandardService : Failed to start connector [Connector[HTTP/1.1-8080]]
org.apache.catalina.LifecycleException: Failed to start component [Connector[HTTP/1.1-8080]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.catalina.core.StandardService.addConnector(StandardService.java:225) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.addPreviouslyRemovedConnectors(TomcatEmbeddedServletContainer.java:247) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.start(TomcatEmbeddedServletContainer.java:190) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.startEmbeddedServletContainer(EmbeddedWebApplicationContext.java:297) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.finishRefresh(EmbeddedWebApplicationContext.java:145) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546) [spring-context-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:762) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:372) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1187) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1176) [spring-boot-1.4.7.RELEASE.jar:1.4.7.RELEASE]
at com.gl.demo2.Demo2Application.main(Demo2Application.java:10) [classes/:na]
Caused by: org.apache.catalina.LifecycleException: service.getName(): "Tomcat"; Protocol handler start failed
at org.apache.catalina.connector.Connector.startInternal(Connector.java:1029) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
... 13 common frames omitted
Caused by: java.net.BindException: Address already in use: bind
at sun.nio.ch.Net.bind0(Native Method) ~[na:1.8.0_77]
at sun.nio.ch.Net.bind(Net.java:433) ~[na:1.8.0_77]
at sun.nio.ch.Net.bind(Net.java:425) ~[na:1.8.0_77]
at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223) ~[na:1.8.0_77]
at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74) ~[na:1.8.0_77]
at org.apache.tomcat.util.net.NioEndpoint.bind(NioEndpoint.java:210) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.tomcat.util.net.AbstractEndpoint.start(AbstractEndpoint.java:978) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.coyote.AbstractProtocol.start(AbstractProtocol.java:628) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
at org.apache.catalina.connector.Connector.startInternal(Connector.java:1022) ~[tomcat-embed-core-8.5.15.jar:8.5.15]
... 14 common frames omitted
2018-01-31 21:58:49.608 INFO 14148 --- [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat]
2018-01-31 21:58:49.620 INFO 14148 --- [ main] utoConfigurationReportLoggingInitializer :
Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2018-01-31 21:58:49.625 ERROR 14148 --- [ main] o.s.b.d.LoggingFailureAnalysisReporter :
***************************
APPLICATION FAILED TO START
***************************
Description:
The Tomcat connector configured to listen on port 8080 failed to start. The port may already be in use or the connector may be misconfigured.
Action:
Verify the connector's configuration, identify and stop any process that's listening on port 8080, or configure this application to listen on another port.
2018-01-31 21:58:49.626 INFO 14148 --- [ main] ationConfigEmbeddedWebApplicationContext : Closing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@1a561cf: startup date [Wed Jan 31 21:58:47 CST 2018]; root of context hierarchy
2018-01-31 21:58:49.627 INFO 14148 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Unregistering JMX-exposed beans on shutdown
Process finished with exit code 1
百度看有前辈说造成这种情况的原因是：端口被占用，我以为是我还有tomcat开启才导致这个错误，于是我把其他打开的窗口都关闭，还是一样的报这个错误。我最后把所有的关闭，再次重启还是一样报错。
最后我设置项目属性配置application.properties（server.port=8081）：
终于可以了，继续加油学习！