1. 去除Spring-boot-start-web中的Tomcat的依赖

     <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>

1. 修改POM中的<packaging>jar</packaging>  为  <packaging>war</packaging>

1. 添加Servlet的依赖包

<dependency>

            <groupId>javax.servlet</groupId>

            <artifactId>javax.servlet-api</artifactId>

            <version>3.1.0</version>

            <scope>provided</scope>

        </dependency>

1. 启动类继承  extends SpringBootServletInitializer

覆盖 configure方法

将builder的sources中的启动指向原来的启动类

例如