protocal handeler started failed

org.apache.catalina.LifecycleException: Protocol handler start failed
	at org.apache.catalina.connector.Connector.startInternal(Connector.java:1008) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
	at org.apache.catalina.core.StandardService.addConnector(StandardService.java:226) [tomcat-embed-core-9.0.17.jar:9.0.17]
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.addPreviouslyRemovedConnectors(TomcatWebServer.java:259) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.start(TomcatWebServer.java:197) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.startWebServer(ServletWebServerApplicationContext.java:311) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:164) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:552) [spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at cn.itcast.user.UserApplication.main(UserApplication.java:11) [classes/:na]
Caused by: java.net.BindException: Address already in use: bind
	at sun.nio.ch.Net.bind0(Native Method) ~[na:1.8.0_252]
	at sun.nio.ch.Net.bind(Net.java:433) ~[na:1.8.0_252]
	at sun.nio.ch.Net.bind(Net.java:425) ~[na:1.8.0_252]
	at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:220) ~[na:1.8.0_252]
	at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:85) ~[na:1.8.0_252]
	at org.apache.tomcat.util.net.NioEndpoint.initServerSocket(NioEndpoint.java:236) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
	at org.apache.tomcat.util.net.NioEndpoint.bind(NioEndpoint.java:210) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
	at org.apache.tomcat.util.net.AbstractEndpoint.bindWithCleanup(AbstractEndpoint.java:1103) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
	at org.apache.tomcat.util.net.AbstractEndpoint.start(AbstractEndpoint.java:1189) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
	at org.apache.coyote.AbstractProtocol.start(AbstractProtocol.java:568) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
	at org.apache.catalina.connector.Connector.startInternal(Connector.java:1005) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
	... 14 common frames omitted

解决:
这是进程被占用了。先管理员身份运行cmd,输入netstat -ano,找到占用你端口的pid,杀死进程用taskkill /pid xxx -f即可。