maven打包springboot成war包

报错一：

Failed to execute goal org.apache.maven.plugins:maven-war-plugin:2.2:war (default-war) on project Ocr: Error assembling WAR: webxml attribute is required (or pre-existing WEB-INF/web.xml if executing in update mode)

解决:新建图中目录webapp/WEB-INFO/web/xml，web.xml不需要额外写内容

报错二：

程序包javax.servlet不存在
解决：添加依赖

        <!-- 解决编译时，报程序包javax.servlet不存在的错误 -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <!-- 只在编译和测试的时候用 -->
            <scope>provided</scope>
        </dependency>

重新打包即可
clean->package

如何打包成war

1.修改pom打包方式，为war

2.修改启动类

@SpringBootApplication
public class DemoApplication extends SpringBootServletInitializer {

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

    // 用于构建war文件并进行部署
    @Override
    protected SpringApplicationBuilder configure(
            SpringApplicationBuilder builder) {
        return builder.sources(this.getClass());
    }


}

3.移除springboot内嵌的tomcat

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <!-- 移除嵌入式tomcat插件 -->
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>