[笔记]spring boot打包jar和war

1. 打包jar
   Spring官网Guides下任意一个例子，比如最简单的Building a RESTful Web Service

2. 打包war
   参考Spring Boot文档 Traditional deployment 85.1 Create a deployable war file
   或例程 spring-boot-sample-war

   按例程看，如果@SpringBootApplication的class直接继承了SpringBootServletInitializer，不用重写config方法也是可以的（builder.main(getClass())、get的就是应用class）。

3. 打包一个又能发布于tomcat又能java -jar直接跑的war
   2的参考文档里有：

   If you’re using the Spring Boot build tools, marking the embedded servlet container dependency as provided will produce an executable war file with the provided dependencies packaged in a lib-provided directory.

   另外：
   Maven 66.2 Packaging executable jar and war files
   Gradle 67.3 Packaging executable jar and war files

   观察几种配置的发布包子目录和其下jar包，并比较MENIFEST.MF：
   bootRun时有：

   Start-Class: hello.Application
   Spring-Boot-Classes: BOOT-INF/classes/
   Spring-Boot-Lib: BOOT-INF/lib/
   Main-Class: org.springframework.boot.loader.JarLauncher

   不过关心的是war包：

   Start-Class: hello.Application
   Spring-Boot-Classes: WEB-INF/classes/
   Spring-Boot-Lib: WEB-INF/lib/
   Main-Class: org.springframework.boot.loader.WarLauncher

   应该是丢给tomcat时、tomcat只检查servlet定义的WEB-INF/lib路径，但java -jar时、Spring的WarLauncher还引入了存放着tomcat相关jar的lib-provided目录：

   @Override
   public boolean isNestedArchive(Archive.Entry entry) {
   if (entry.isDirectory()) {
   return entry.getName().equals(WEB_INF_CLASSES);
       }
   else {
   return entry.getName().startsWith(WEB_INF_LIB)
                   || entry.getName().startsWith(WEB_INF_LIB_PROVIDED);
       }
   }

   所以两种都能跑。