错误解析：org.apache.catalina.LifecycleException: Protocol handler start failed

以下是报错代码：

org.apache.catalina.LifecycleException: Protocol handler start failed

at org.apache.catalina.connector.Connector.startInternal(Connector.java:1008) ~[tomcat-embed-core-9.0.24.jar:9.0.24]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.24.jar:9.0.24]
at org.apache.catalina.core.StandardService.addConnector(StandardService.java:227) [tomcat-embed-core-9.0.24.jar:9.0.24]
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.addPreviouslyRemovedConnectors(TomcatWebServer.java:263) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.start(TomcatWebServer.java:195) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.startWebServer(ServletWebServerApplicationContext.java:297) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:163) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:552) [spring-context-5.1.9.RELEASE.jar:5.1.9.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204) [spring-boot-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at com.job.subsidy.JobsubsidyApplication.main(JobsubsidyApplication.java:23) [classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_171]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_171]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_171]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_171]
at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.1.8.RELEASE.jar:2.1.8.RELEASE]

Caused by: java.net.BindException: Address already in use: bind

at sun.nio.ch.Net.bind0(Native Method) ~[na:1.8.0_171]
at sun.nio.ch.Net.bind(Net.java:433) ~[na:1.8.0_171]
at sun.nio.ch.Net.bind(Net.java:425) ~[na:1.8.0_171]
at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223) ~[na:1.8.0_171]
at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74) ~[na:1.8.0_171]
at org.apache.tomcat.util.net.NioEndpoint.initServerSocket(NioEndpoint.java:230) ~[tomcat-embed-core-9.0.24.jar:9.0.24]
at org.apache.tomcat.util.net.NioEndpoint.bind(NioEndpoint.java:213) ~[tomcat-embed-core-9.0.24.jar:9.0.24]
at org.apache.tomcat.util.net.AbstractEndpoint.bindWithCleanup(AbstractEndpoint.java:1124) ~[tomcat-embed-core-9.0.24.jar:9.0.24]
at org.apache.tomcat.util.net.AbstractEndpoint.start(AbstractEndpoint.java:1210) ~[tomcat-embed-core-9.0.24.jar:9.0.24]
at org.apache.coyote.AbstractProtocol.start(AbstractProtocol.java:585) ~[tomcat-embed-core-9.0.24.jar:9.0.24]
at org.apache.catalina.connector.Connector.startInternal(Connector.java:1005) ~[tomcat-embed-core-9.0.24.jar:9.0.24]
... 19 common frames omitted

错误原因：端口被占用，所以启动失败。

解决方法：

第一种解决方法：简单粗暴方式：直接修改端口号，重启项目。

第二种解决方法：关掉java进程，再重启项目。

第三种解决方法：或者直接在命令行操作：

      使用命令：netstat -nao|findstr 端口号（端口号是自己在项目里自己设置的）

      杀死这个端口号的进程，使用命令：taskkill /pid 进程号（这进程号是自己服务器上的进程号）-t -f

      图片中的第二行TCP中的 6789 是为端口被占用 进程号为 33172

以下是运行cmd小黑窗的结果（咳咳，那个错误不要在意[尴尬]/[尴尬]/[尴尬][表情包]）