Spring boot教程之Spring boot简单快速入门从HelloWorld开始

转载来源于：Springboot学习篇之搭建HelloWorld初探

一、前言

Spring boot是由Pivotal团队提供的全新框架，其设计目的是用来简化新Spring应用的初始搭建以及开发过程。该框架使用了特定的方式来进行配置，从而使开发人员不再需要定义样板化的配置。
Spring boot包含的特性：
♦创建独立的Spring应用程序
♦嵌入Tomcat，无需部署war文件
♦简化Maven配置
♦自动配置Spring
♦提供生产就绪功能，如指标，健康检查和外部配置
♦开箱即用，没有代码生成，也无需XML配置
为基于Spring的开发提供更快的入门体验，开箱即用，没有代码生成，也无需XML配置。同时也可以修改默认值来满足特定需求。提供了一些大型项目中常见的非功能特性，如嵌入式服务器、安全、指标、健康体检、外部配置等。Spring boot并不是对Spring功能的增强，而是提供了一种快速使用Spring的方式。

二、准备

开发环境：1.7.0_79
开发工具：Eclipse
项目管理工具：Maven3
操作系统：Windows8
Spring boot版本：1.4.1.RELEASE

三、步骤

♦搭建一个Maven工程SpringBootHelloWorld

♦POM文件中导入相关依赖

	4.0.0
	com.queen.springboot
	SpringBootHelloWorld
	0.0.1-SNAPSHOT
	
		org.springframework.boot
		spring-boot-starter-parent
		1.4.1.RELEASE
	
	
		UTF-8
		1.7
	
	
		
			org.springframework.boot
			spring-boot-starter-web
		
	

我们引入了Spring boot的父节点依赖，引入这个之后相关的引用就不需要添加version配置了，Spring boot会自动选择最合适的版本进行添加。
环境中我们指定JDK的版本为1.7，默认是1.6
导入spring-boot-starter-web依赖这个地方我们没有指定版本号，是因为上面我们配置了parent，所以不用添加了。

♦编写控制类SpringBootHelloWorld

/**
 * @author queen
 * @since 2017-07-16
 *
 */
@RestController
public class HelloWorldController {
	
	@RequestMapping("/hello")
	public String sayHello() {
		return "helloWorld";
	}
}

这里我们使用的@RestController注解等价于@Controller和@ResponseBody注解，使用@RequestMapping建立请求映射。

♦编写启动类APP

/**
 * @author queen
 * @since 2017-07-16
 *
 */
@SpringBootApplication
public class APP {

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

}

使用@SpringBootApplication注解定义APP是一个SpringBoot类型的应用，在main方法中使用SpringApplication的run方法启动我们的程序。

♦右键Run As -> Java Application，启动应用，控制台启动日志如下：

 .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.4.1.RELEASE)

2017-07-16 10:31:07.706  INFO 12108 --- [           main] com.queen.controller.APP                 : Starting APP on Lenovo-PC with PID 12108 (E:\queen\SpringBootHelloWorld\target\classes started by think in E:\queen\SpringBootHelloWorld)
2017-07-16 10:31:07.709  INFO 12108 --- [           main] com.queen.controller.APP                 : No active profile set, falling back to default profiles: default
2017-07-16 10:31:07.814  INFO 12108 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@6568614: startup date [Sun Jul 16 10:31:07 CST 2017]; root of context hierarchy
2017-07-16 10:31:10.086  INFO 12108 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2017-07-16 10:31:10.099  INFO 12108 --- [           main] o.apache.catalina.core.StandardService   : Starting service Tomcat
2017-07-16 10:31:10.101  INFO 12108 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.5
2017-07-16 10:31:10.201  INFO 12108 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2017-07-16 10:31:10.202  INFO 12108 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2392 ms
2017-07-16 10:31:10.411  INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2017-07-16 10:31:10.415  INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2017-07-16 10:31:10.417  INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2017-07-16 10:31:10.417  INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2017-07-16 10:31:10.417  INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2017-07-16 10:31:10.812  INFO 12108 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@6568614: startup date [Sun Jul 16 10:31:07 CST 2017]; root of context hierarchy
2017-07-16 10:31:10.906  INFO 12108 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello]}" onto public java.lang.String com.queen.controller.HelloWorldController.sayHello()
2017-07-16 10:31:10.913  INFO 12108 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2017-07-16 10:31:10.913  INFO 12108 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2017-07-16 10:31:10.965  INFO 12108 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-07-16 10:31:10.966  INFO 12108 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-07-16 10:31:11.013  INFO 12108 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-07-16 10:31:11.320  INFO 12108 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2017-07-16 10:31:11.391  INFO 12108 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2017-07-16 10:31:11.398  INFO 12108 --- [           main] com.queen.controller.APP                 : Started APP in 4.301 seconds (JVM running for 4.619)

启动后默认端口号是8080

♦使用http://localhost:8080/hello看是否能够访问我们的应用

访问成功。
至此，我们使用Spring boot搭建的第一个HelloWorld小程序完成。