spring boot經過war包的形式部署

面試分享：今天遇到一個面試官必定讓我講出spring boot經過war包的形式部署，一問就答不上來了，通常在項目上都是經過jar包的形式部署，如今總結一下：
步驟一：下載tomcat https://tomcat.apache.org/download-80.cgi
步驟二：重寫SpringBootServletInitializer啓動類的configure
默認狀況外部Tomcat不能讀取到Spring Boot 入口類的main方法啓動程序加載，使用須要繼承，代碼以下：

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

/**
 * 重寫configure方法，加載啓動類
 * @param builder
 * @return
 */
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
    return builder.sources(DefinedExternalTomcatApplication.class);
}

}

步驟三：修改pom.xml文件
1.排除一下內置tomcat的jar包，防止打包以後與外面Tomcat jar 包衝突，致使項目啓動失敗，<exclusions></exclusion>
2.將<packaging>war</packaging>

內容以下：
<?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>
<!-- 這裏打成war包 若打jar，需將war改成jar -->
<packaging>war</packaging>

<name>springbootDemo</name>
<description>springboo外置tomcat</description>
<!-- springboot依賴-->
<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>
         <!-- 去除內嵌tomcat -->
                <exclusions>
                    <exclusion>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-starter-tomcat</artifactId>
                    </exclusion>
                </exclusions>
</dependency>
       <!--添加servlet的依賴-->
<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>3.1.0</version>
  <scope>provided</scope>
</dependency>

<dependencies>
<!-- springboot操做數據庫-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>

<!-- springboot與mysql驅動整合-->
    <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
    </dependency>
    <!-- springboot測試->
    <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：將項目打成war包，部署到外部的tomcat中，這個時候，不能直接訪問spring boot 項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內置的tomcat的端口號, 打成war包部署在獨立的tomcat上以後, 你配置的server.port是不起做用的。必定要注意這一點！！

總結：war（java application archive）包與Jar（java application archive）包區別：

war包是基本web應用的應用程序（須要經過web應用在運行，如tomcat,Websphere、Jetty等）
            jar包是基於jar的應用程序（只須要安裝jdk就能夠）