Spring Boot CLI（Command Line Interface）是一个命令行工具，您可以用它来快速构建Spring原型应用。通过Spring Boot CLI，我们可以通过编写Groovy脚本来快速的构建出Spring Boot应用，并通过命令行的方式将其运行起来。下来，我们来学习一下如何安装和使用Spring Boot CLI。
安装Spring Boot CLI
关于Spring Boot CLI的安装方式有很多，这里根据目前主要主流的开发平台，具体介绍一下Windows和Mac下的安装方式：
通用安装
先介绍一个所有平台都可以使用的安装方法。
第一步：下载Spring Boot CLI的工具包：
第二步：解压下载内容，可以看到bin目录下已经有适用于windows和linux平台的两个可执行文件了，我们已经可以直接使用它；为了更方便的使用Spring Boot CLI的命令，我们可以将上面bin目录中对应的可执行文件加入到当前系统的环境变量即可。
Mac OSX Brew安装
在Mac OSX系统下面就非常方便了，我们可以通过Brew来进行安装，只需要分别执行下面的两条的命令即可：
$ brew tap pivotal/tap
$ brew install springboot
验证安装
不论使用哪种方法安装，在安装好之后，我们可以通过下面的命令来验证一下当前的安装结果：
$ spring --version
Spring CLI v2.0.0.RELEASE
运行Groovy脚本
在完成了Spring Boot CLI的安装之后，我们来试试使用它来快速的构建一个Spring Boot应用，方法很简单，只需要如下操作：
第一步：新建一个Groovy脚本，hello.groovy，内容如下：
@RestController
class ThisWillActuallyRun {
@RequestMapping("/")
String home() {
"Hello World!"
}
}
第二步：使用spring命令运行该Groovy脚本，具体如下：
$ spring run hello.groovy
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2018-04-04 18:11:20.571 INFO 70477 --- [ runner-0] o.s.boot.SpringApplication : Starting application on zhaiyongchaodeMacBook-Pro.local with PID 70477 (started by zhaiyongchao in /Users/zhaiyongchao/Downloads)
2018-04-04 18:11:20.574 INFO 70477 --- [ runner-0] o.s.boot.SpringApplication : No active profile set, falling back to default profiles: default
2018-04-04 18:11:20.732 INFO 70477 --- [ runner-0] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@3c3ad454: startup date [Wed Apr 04 18:11:20 CST 2018]; root of context hierarchy
2018-04-04 18:11:21.758 INFO 70477 --- [ runner-0] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2018-04-04 18:11:21.783 INFO 70477 --- [ runner-0] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2018-04-04 18:11:21.784 INFO 70477 --- [ runner-0] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.28
2018-04-04 18:11:21.795 INFO 70477 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/Users/zhaiyongchao/Library/Java/Extensions:/Library/Java/Extensions:/Network/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java:.]
2018-04-04 18:11:21.849 INFO 70477 --- [ost-startStop-1] org.apache.catalina.loader.WebappLoader : Unknown loader org.springframework.boot.cli.compiler.ExtendedGroovyClassLoader$DefaultScopeParentClassLoader@5e3b901 class org.springframework.boot.cli.compiler.ExtendedGroovyClassLoader$DefaultScopeParentClassLoader
2018-04-04 18:11:21.884 INFO 70477 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2018-04-04 18:11:21.885 INFO 70477 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1153 ms
2018-04-04 18:11:22.042 INFO 70477 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/]
2018-04-04 18:11:22.049 INFO 70477 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-04-04 18:11:22.049 INFO 70477 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-04-04 18:11:22.049 INFO 70477 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-04-04 18:11:22.049 INFO 70477 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2018-04-04 18:11:22.391 INFO 70477 --- [ runner-0] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@3c3ad454: startup date [Wed Apr 04 18:11:20 CST 2018]; root of context hierarchy
2018-04-04 18:11:22.489 INFO 70477 --- [ runner-0] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto public java.lang.String ThisWillActuallyRun.home()
2018-04-04 18:11:22.495 INFO 70477 --- [ runner-0] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-04-04 18:11:22.496 INFO 70477 --- [ runner-0] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-04-04 18:11:22.550 INFO 70477 --- [ runner-0] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-04-04 18:11:22.550 INFO 70477 --- [ runner-0] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-04-04 18:11:22.598 INFO 70477 --- [ runner-0] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-04-04 18:11:22.955 INFO 70477 --- [ runner-0] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2018-04-04 18:11:23.004 INFO 70477 --- [ runner-0] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2018-04-04 18:11:23.010 INFO 70477 --- [ runner-0] o.s.boot.SpringApplication : Started application in 17.605 seconds (JVM running for 79.248)
从日志中我们可以看到我们通过Groovy脚本定义的一个简单web应用就构建成功了，可以通过访问localhost:8080来验证一下上面应用提供的接口：
$ curl localhost:8080
Hello World!
是不是非常简单？有木有颠覆您对Java应用的印象？
