启动失败Unable to start embedded Tomcat server

org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat server
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.start(TomcatWebServer.java) 
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.startWebServer(ServletWebServerApplicationContext.java) 
at  org.springframework.boot.web.embedded.tomcat.TomcatWebServer.start(TomcatWebServer.java) 
Caused by: org.apache.catalina.LifecycleException: Protocol handler start failed
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java)
Caused by: java.net.SocketException: Permission denied

原因是端口号被占用了，修改一下端口号。