使用assembly插件对boot项目打zip和war部署包

<!--配置不同的打包配置，如果不指定参数。默认一最后的profile配置为准，即，如下配置，默认打zip--><profiles><!--打war包的配置--><profile><id>war</id><activation><activeByDefault>true</activeByDefault><property><name>type</name><value>war</value></property></activation><properties><type>war</type></properties><build><plugins><plugin><artifactId>maven-assembly-plugin</artifactId><configuration><descriptors>src/main/assembly/l</descriptors></configuration></plugin></plugins></build></profile><!--打zip包的配置--><profile><id>zip</id><activation><activeByDefault>true</activeByDefault><property><name>type</name><value>zip</value></property></activation><properties><type>zip</type></properties><build><plugins><plugin><artifactId>maven-assembly-plugin</artifactId><configuration><descriptors>src/main/l</descriptors></configuration></plugin></plugins></build></profile></profiles>

再添加一个l

<?xml version="1.0" encoding="UTF-8" ?>
<assembly><id>assembly</id><formats><format>war</format></formats><includeBaseDirectory>false</includeBaseDirectory><fileSets><fileSet><directory>{basedir}/target/classes</directory><fileMode>0755</fileMode><outputDirectory>WEB-INF/classes</outputDirectory></fileSet></fileSets><dependencySets><dependencySet><outputDirectory>WEB-INF/lib</outputDirectory><useProjectArtifact>false</useProjectArtifact></dependencySet></dependencySets>
</assembly>

这样我们就可以通过mvn clean install -P war|zip来打不同的包了

三、boot项目如何转成war包部署

我们知道boot的项目会自动生成一个启动类，并通过该启动类启动

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

跟踪SpringApplication.run方法发现，核心方法为：org.springframework.boot.SpringApplication#run(java.)

public ConfigurableApplicationContext  args) {long startTime = System.nanoTime();DefaultBootstrapContext bootstrapContext = ateBootstrapContext();ConfigurableApplicationContext context = figureHeadlessProperty();SpringApplicationRunListeners listeners = RunListeners(args);listeners.starting(bootstrapContext, this.mainApplicationClass);try {ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);//创建并配置当前SpringBoot应用将要使用的Environment（包括配置要使用的PropertySource以及Profile）,//并遍历调用所有的SpringApplicationRunListener的environmentPrepared()方法，广播Environment准备完毕。ConfigurableEnvironment environment = this.prepareEnvironment(listeners, bootstrapContext, applicationArguments);figureIgnoreBeanInfo(environment);Banner printedBanner = this.printBanner(environment);//根据webEnvironment的值来决定创建何种类型的ApplicationContext对象//如果是web环境，则创建org.t.embedded.AnnotationConfigEmbeddedWebApplicationContext//否则创建t.annotation.AnnotationConfigApplicationContextcontext = ateApplicationContext();context.setApplicationStartup(this.applicationStartup);//主要是调用所有初始化类的 initialize 方法this.prepareContext(bootstrapContext, context, environment, listeners, applicationArguments, printedBanner);//初始化 Spring 容器freshContext(context);this.afterRefresh(context, applicationArguments);Duration timeTakenToStartup = Duration.ofNanos(System.nanoTime() - startTime);if (this.logStartupInfo) {(new StartupInfoLogger(this.mainApplicationClass)).ApplicationLog(), timeTakenToStartup);}listeners.started(context, timeTakenToStartup);//调用 ApplicationRunner 或者 CommandLineRunner 的运行方法this.callRunners(context, applicationArguments);} catch (Throwable var12) {this.handleRunFailure(context, var12, listeners);throw new IllegalStateException(var12);}try {Duration timeTakenToReady = Duration.ofNanos(System.nanoTime() - startTime);ady(context, timeTakenToReady);return context;} catch (Throwable var11) {this.handleRunFailure(context, var11, (SpringApplicationRunListeners)null);throw new IllegalStateException(var11);}}

那么问题来了，转成war部署后，如何由web容器拉起这个过程呢？ 其实boot已经给我们考虑过了

，boot提供了一个SpringBootServletInitializer类，修改如下：

@SpringBootApplicationpublic class BootdemoApplication extends SpringBootServletInitializer {public static void main(String[] args) {SpringApplication.run(BootdemoApplication.class, args);}@Overrideprotected SpringApplicationBuilder configure(SpringApplicationBuilder application) {return application.sources(BootdemoApplication.class);}}

如果启动类无法继承（如启动类已经有了父类），可以新建一个类继承SpringBootServletInitializer，并重写configure即可：

    public class ProjectServletInitializer extends SpringBootServletInitializer {@Overrideprotected SpringApplicationBuilder configure(SpringApplicationBuilder application) {return application.sources(BootdemoApplication.class);}}

 跟踪源码发现，最终还是在web容器启动的时候调用到了org.springframework.boot.SpringApplication#run(java.)

大致原理如下：

1、spring-boot的SpringBootServletInitializer类实现了spring-web的 WebApplicationInitializer接口

public interface WebApplicationInitializer {void onStartup(ServletContext servletContext) throws ServletException;
}

public abstract class SpringBootServletInitializer implements WebApplicationInitializer {protected Log logger;private boolean registerErrorPageFilter = true;public SpringBootServletInitializer() {}protected final void setRegisterErrorPageFilter(boolean registerErrorPageFilter) {isterErrorPageFilter = registerErrorPageFilter;}public void onStartup(ServletContext servletContext) throws ServletException {servletContext.setAttribute(&#ister-shutdown-hook", false);this.logger = Class());//重点方法，这里最终会调用到SpringApplication#runWebApplicationContext rootApplicationContext = ateRootApplicationContext(servletContext);if (rootApplicationContext != null) {servletContext.addListener(new SpringBootServletInitializer.SpringBootContextLoaderListener(rootApplicationContext, servletContext));} else {this.logger.debug("No ContextLoaderListener registered, as createRootApplicationContext() did not return an application context");}}
//...
}

2、和WebApplicationInitializer类同一目录下有一个SpringServletContainerInitializer类，该类实现了javax.servlet-api的ServletContainerInitializer接口，并将WebApplicationInitializer类通过注解@HandlesTypes传递给了onStartup方法的第一个参数

@HandlesTypes({WebApplicationInitializer.class})
public class SpringServletContainerInitializer implements ServletContainerInitializer {public SpringServletContainerInitializer() {}public void onStartup(@Nullable Set<Class<?>> webAppInitializerClasses, ServletContext servletContext) throws ServletException {List<WebApplicationInitializer> initializers = ptyList();Iterator var4;if (webAppInitializerClasses != null) {initializers = new ArrayList(webAppInitializerClasses.size());var4 = webAppInitializerClasses.iterator();while(var4.hasNext()) {Class<?> waiClass = (();if (!waiClass.isInterface() && !Modifier.Modifiers()) && WebApplicationInitializer.class.isAssignableFrom(waiClass)) {try {((List)initializers).add((WebApplicationInitializer)ReflectionUtils.accessibleConstructor(waiClass, new Class[0]).newInstance());} catch (Throwable var7) {throw new ServletException("Failed to instantiate WebApplicationInitializer class", var7);}}}}if (((List)initializers).isEmpty()) {servletContext.log("No Spring WebApplicationInitializer types detected on classpath");} else {servletContext.log(((List)initializers).size() + " Spring WebApplicationInitializers detected on classpath");AnnotationAwareOrderComparator.sort((List)initializers);var4 = ((List)initializers).iterator();while(var4.hasNext()) {WebApplicationInitializer initializer = (();//重点Startup(servletContext);}}}
}

ServletContainerInitializer 是 Servlet 3.0 新增的一个接口，主要用于在web容器启动时为提供给第三方组件机会做一些初始化的工作，例如注册servlet或者filtes等。

每个框架要使用ServletContainerInitializer就必须在对应的jar包的META-INF/services 目录创建一个名为javax.servlet.ServletContainerInitializer的文件，文件内容指定具体的ServletContainerInitializer实现类（即SPI机制），那么，当web容器启动时就会运行这个初始化器做一些组件内的初始化工作。

 这样，就可以将boot项目通过assembly插件打成war包并部署到web容器了~