Springboot 启动异常--ApplicationContextException: ...missing ServletWebServerFactory bean

• 问题

不占用端口启动时，程序正常执行，下面为两种springboot启动方式：

 //使用纯后台方式启动，不占用端口，springboot2.0以后的写法
new SpringApplicationBuilder().sources(Application.class).web(WebApplicationType.NONE).run(args);
        
//使用web方式启动，会占用端口
SpringApplication.run(Application.class, args);

后来需要开放端口，使用HTTP调用，就修改了Springboot启动方式，然后就无法启动了，并抛出以下异常：

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)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:544)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:780)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:333)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1277)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1265)
    at com.linkcld.analysis.Application.main(Application.java:24)
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)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:178)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:152)
    ... 8 common frames omitted

 

解决方法：

看有些人回答比较复杂，什么内嵌tomcat冲突的，什么缺少注解的，我的情况就比较简单了，添加 spring-boot-starter-web 依赖即可：

    org.springframework.boot
    spring-boot-starter-web
    
    2.0.5.RELEASE

问题解决。