BindException: アドレスはすでに使用中です：バインドエラー解決

Spring Bootの学習を続けながら、新しいSpring Bootプロジェクトを作成し、プロジェクトをビルドした後、テストすると、次のエラーが発生しました。

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.]
	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.]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1187) [spring-boot-1.4.7.RELEASE.jar:1.4.7.]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1176) [spring-boot-1.4.7.RELEASE.jar:1.4.7.]
	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]]

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.TomcatEmbe
	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.]
	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.]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1187) [spring-boot-1.4.7.RELEASE.jar:1.4.7.]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1176) [spring-boot-1.4.7.RELEASE.jar:1.4.7.]
	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 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 J

       バイドゥは、その原因をこう語った前任者に注目する。 港が占領されている tomcatを開いているからこのエラーが発生するのだと思い、他に開いているウィンドウをすべて閉じましたが、それでも同じエラーが発生しました。最終的に全部閉じて、もう一度再起動しましたが、エラーはそのままでした。

       最後にプロジェクトのプロパティを設定し、application.propertiesを構成してみました( server.port = 8081 ).

やっと動いた！これからも頑張って勉強してください。