一.修改pom
1. 将jar改成war，没有则添加
<packaging>war</packaging>
2.引入依赖
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-tomcat</artifactId></dependency>
二.修改启动类
启动类继承 SpringBootServletInitializer
三.build
<build><finalName>打成的war的名字</finalName><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins>
</build>