经过测试，发现tomcat的运行效率是没有undertow高的，我们如果要切换默认的运行容器的话，很简单，只需要修改pom.xml即可，其实就是排除tomcat，加入undertow的依赖，如下图是pom.xml的所有内容

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>cn.forever.springboot</groupId>
  <artifactId>springboot-tomcat-undertow</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>2.0.0.RELEASE</version>
  </parent>
  <dependencies>
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-web</artifactId>
          <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
      </dependency>
      <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-undertow</artifactId>
</dependency>
  </dependencies>
</project>