spring boot经过war包的形式部署

面试分享：今天遇到一个面试官必定让我讲出spring boot经过war包的形式部署，一问就答不上来了，通常在项目上都是经过jar包的形式部署，如今总结一下：
步骤一：下载tomcat https://tomcat.apache.org/download-80.cgi
步骤二：重写SpringBootServletInitializer启动类的configure
默认状况外部Tomcat不能读取到Spring Boot 入口类的main方法启动程序加载，使用须要继承，代码以下：

@SpringBootApplication
    public class DefinedExternalTomcatApplication extends SpringBootServletInitializer {
public static void main(String[] args) {
  SpringApplication.run(DefinedExternalTomcatApplication.class, args);
}

/**
 * 重写configure方法，加载启动类
 * @param builder
 * @return
 */
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
    return builder.sources(DefinedExternalTomcatApplication.class);
}

}

步骤三：修改pom.xml文件
1.排除一下内置tomcat的jar包，防止打包以后与外面Tomcat jar 包冲突，致使项目启动失败，<exclusions></exclusion>
2.将<packaging>war</packaging>

内容以下：
<?xml version="1.0" encoding="UTF-8"?>
<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.cqs</groupId>
<artifactId>springbootDemo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<!-- 这里打成war包 若打jar，需将war改成jar -->
<packaging>war</packaging>

<name>springbootDemo</name>
<description>springboo外置tomcat</description>
<!-- springboot依赖-->
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.4.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <project.build.sourceEncoding>UTF8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>
<!-- springboot支持web-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
         <!-- 去除内嵌tomcat -->
                <exclusions>
                    <exclusion>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-starter-tomcat</artifactId>
                    </exclusion>
                </exclusions>
</dependency>
       <!--添加servlet的依赖-->
<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>3.1.0</version>
  <scope>provided</scope>
</dependency>

<dependencies>
<!-- springboot操做数据库-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>

<!-- springboot与mysql驱动整合-->
    <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
    </dependency>
    <!-- springboot测试->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        </dependency>
    </dependencies>
<build>
    <finalName>springbootDemo</finalName>
    <plugins>
    <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
    </plugin>
    </plugins>
</build>
</project>

注意：将项目打成war包，部署到外部的tomcat中，这个时候，不能直接访问spring boot 项目中配置文件配置的端口。application.yml中配置的server.port配置的是spring boot内置的tomcat的端口号, 打成war包部署在独立的tomcat上以后, 你配置的server.port是不起做用的。必定要注意这一点！！

总结：war（java application archive）包与Jar（java application archive）包区别：

war包是基本web应用的应用程序（须要经过web应用在运行，如tomcat,Websphere、Jetty等）
            jar包是基于jar的应用程序（只须要安装jdk就能够）