启动Springboot项目报以下异常：

　　

org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:155) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:544) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]at hello.Application.main(Application.java:13) [classes/:na]
Caused by: org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.getWebServerFactory(ServletWebServerApplicationContext.java:204) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:178) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:152) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]...8 common frames omitte

　　很明显是提示Application无法获取ServletWebServerFactory实例，首先要注意， 由于Springboot在以往使用Spring都要配置下提供了集成方案，所以最简单的方法就是采用默认的配置，解决方法非常简单，只需在你的启动类中加入@EnableAutoConfiguration，当然你也可以手动配置，如下为自动配置。

packagehello;importorg.springframework.boot.CommandLineRunner;importorg.springframework.boot.SpringApplication;importorg.springframework.boot.autoconfigure.EnableAutoConfiguration;importorg.springframework.context.ApplicationContext;importorg.springframework.context.annotation.Bean;importjava.util.Arrays;
@EnableAutoConfigurationpublic classApplication {public static voidmain(String[] args) {SpringApplication.run(Application.class, args);}@BeanpublicCommandLineRunner commandLineRunner(ApplicationContext ctx) {return args ->{System.out.println("Let's inspect the beans provided by Spring Boot:");String[] beanNames=ctx.getBeanDefinitionNames();Arrays.sort(beanNames);for(String beanName : beanNames) {System.out.println(beanName);}};}
}

　　手动配置请参考官网，地址：https://docs.spring.io/spring-boot/docs/2.0.1.BUILD-SNAPSHOT/reference/html/howto-embedded-web-servers.html#howto-configure-tomcat

　　下面配一个全部手动配置的代码，其中@value标签的内容需要自己写properties文件：

packagecom.gws.configuration;importorg.apache.catalina.connector.Connector;importorg.springframework.beans.factory.annotation.Value;importorg.springframework.boot.web.embedded.tomcat.TomcatConnectorCustomizer;importorg.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;importorg.springframework.boot.web.servlet.MultipartConfigFactory;importorg.springframework.boot.web.servlet.server.ServletWebServerFactory;importorg.springframework.context.annotation.Bean;importorg.springframework.context.annotation.Configuration;importjavax.servlet.MultipartConfigElement;/*** 使用tomcat配置**@version*@author**/@Configurationpublic classTomcatConfig {@Value("${spring.server.port}")privateString port;@Value("${spring.server.acceptorThreadCount}")privateString acceptorThreadCount;@Value("${spring.server.minSpareThreads}")privateString minSpareThreads;@Value("${spring.server.maxSpareThreads}")privateString maxSpareThreads;@Value("${spring.server.maxThreads}")privateString maxThreads;@Value("${spring.server.maxConnections}")privateString maxConnections;@Value("${spring.server.protocol}")privateString protocol;@Value("${spring.server.redirectPort}")privateString redirectPort;@Value("${spring.server.compression}")privateString compression;@Value("${spring.server.connectionTimeout}")privateString connectionTimeout;@Value("${spring.server.MaxFileSize}")privateString MaxFileSize;@Value("${spring.server.MaxRequestSize}")privateString MaxRequestSize;@BeanpublicServletWebServerFactory servletContainer() {TomcatServletWebServerFactory tomcat= newTomcatServletWebServerFactory();tomcat.addConnectorCustomizers(newGwsTomcatConnectionCustomizer());returntomcat;}@BeanpublicMultipartConfigElement multipartConfigElement() {MultipartConfigFactory factory= newMultipartConfigFactory();//单个数据大小factory.setMaxFileSize(MaxFileSize); //KB,MB/// 总上传数据大小
factory.setMaxRequestSize(MaxRequestSize);returnfactory.createMultipartConfig();}/**** 默认http连接**@version*@authorliuyi  2016年7月20日 下午7:59:41**/public class GwsTomcatConnectionCustomizer implementsTomcatConnectorCustomizer {publicGwsTomcatConnectionCustomizer() {}@Overridepublic voidcustomize(Connector connector) {connector.setPort(Integer.valueOf(port));connector.setAttribute("connectionTimeout", connectionTimeout);connector.setAttribute("acceptorThreadCount", acceptorThreadCount);connector.setAttribute("minSpareThreads", minSpareThreads);connector.setAttribute("maxSpareThreads", maxSpareThreads);connector.setAttribute("maxThreads", maxThreads);connector.setAttribute("maxConnections", maxConnections);connector.setAttribute("protocol", protocol);connector.setAttribute("redirectPort", "redirectPort");connector.setAttribute("compression", "compression");}}
}