1、修改pom.xml 

父工程的pom.xml中的 <packaging>pom</packaging>
spring boot项目应用中pom.xml中的 <packaging>war<packaging>
    
<!--在父工程的pom.xml里，去除springboot web自带的tomcat，自己添加tomcat、servlet-api 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>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <scope>provided</scope>
    </dependency>

2.在有启动类的项目中，让启动类继承 SpringBootServletInitializer，重写 configure 方法。 

@SpringBootApplication
public class DemoApplication extends SpringBootServletInitializer {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication .class, args);
    }

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
        // 注意这里要指向原先用main方法执行的Application启动类
        return builder.sources(DemoApplication .class);
    }
}

其他与之相关的异常请前往Springboot、Springcloud、Eureka

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