Spring Boot简介

Spring Boot让我们的Spring应用变的更轻量化。比如：你可以仅仅依靠一个Java类来运行一个Spring引用。你也可以打包你的应用为jar并通过使用java -jar来运行你的Spring Web应用。

Spring Boot的主要优点：

为所有Spring开发者更快的入门 开箱即用，提供各种默认配置来简化项目配置 内嵌式容器简化Web项目 没有冗余代码生成和XML配置的要求

用Spring Boot编写helloworld

1.首先创建一个maven项目

2.添加Spring Boot依赖

通常，让你的Maven POM文件继承 spring-boot-starter-parent，并声明一个或多个 Starter POMs依赖即可。

org.springframework.boot spring-boot-starter-parent 1.5.4.RELEASE UTF-8 UTF-8 1.8 org.springframework.boot spring-boot-starter org.springframework.boot spring-boot-starter-test test org.springframework.boot spring-boot-starter-web

 

3.创建java类，编写helloworld代码

package com.xzh.demo; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.web.bind.annotation.Re; import org.springframework.web.bind.annotation.RestController; @RestController @SpringBootApplication public class DemoApplication { @Re("/hello") public String index() { return "Hello World!!!"; } public static void main(String[] args) { SpringApplication.run(com.xzh.demo.DemoApplication.class, args); } }

核心注解类说明

@RestController

就是@Controller+@ResponseBody组合，支持RESTful访问方式，返回结果都是json字符串

@SpringBootApplication

就是@SpringBootConfiguration+@EnableAutoConfiguration+ @ComponentScan等组合在一起，非常简单，使用也方便

@EnableAutoConfiguration注解

这个注解告诉Spring Boot“猜测”将如何配置Spring。@EnableAutoConfiguration是借助@Import的帮助，将所有符合自动配置条件的bean定义加载到IoC容器。

@ComponentScan

用注解配置实现自动扫描，默认会扫描当前包和所有子包,并加载符合条件的组件(比如@Component和@Repository等)，和xml配置自动扫描效果一样

@SpringBootConfiguration

说明这是一个配置文件类(SpringBoot社区推荐使用基于JavaConfig的配置形式)

 

4.运行创建的java类

2017-07-21 16:18:35.787 INFO 19984 --- [ main] com.xzh.demo.DemoApplication : Starting DemoApplication on LAPTOP-T56QDVQ2 with PID 19984 (F:\workspaceIDEA\helloworld\target\classes started by lenovo in F:\workspaceIDEA\helloworld) 2017-07-21 16:18:35.789 INFO 19984 --- [ main] com.xzh.demo.DemoApplication : No active profile set, falling back to default profiles: default 2017-07-21 16:18:35.837 INFO 19984 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@8646db9: startup date [Fri Jul 21 16:18:35 CST 2017]; root of context hierarchy 2017-07-21 16:18:37.293 INFO 19984 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http) 2017-07-21 16:18:37.305 INFO 19984 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2017-07-21 16:18:37.306 INFO 19984 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.15 2017-07-21 16:18:37.375 INFO 19984 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2017-07-21 16:18:37.375 INFO 19984 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1542 ms 2017-07-21 16:18:37.477 INFO 19984 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/] 2017-07-21 16:18:37.481 INFO 19984 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2017-07-21 16:18:37.481 INFO 19984 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2017-07-21 16:18:37.481 INFO 19984 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*] 2017-07-21 16:18:37.481 INFO 19984 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 're' to: [/*] 2017-07-21 16:18:37.735 INFO 19984 --- [ main] s.w.s.m.m.a.Reapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@8646db9: startup date [Fri Jul 21 16:18:35 CST 2017]; root of context hierarchy 2017-07-21 16:18:37.769 INFO 19984 --- [ main] s.w.s.m.m.a.Repping : Mapped "{[/hello]}" onto public java.lang.String com.xzh.demo.DemoApplication.index() 2017-07-21 16:18:37.772 INFO 19984 --- [ main] s.w.s.m.m.a.Repping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest) 2017-07-21 16:18:37.772 INFO 19984 --- [ main] s.w.s.m.m.a.Repping : 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) 2017-07-21 16:18:37.789 INFO 19984 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRe] 2017-07-21 16:18:37.789 INFO 19984 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRe] 2017-07-21 16:18:37.810 INFO 19984 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRe] 2017-07-21 16:18:37.887 INFO 19984 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup 2017-07-21 16:18:37.916 INFO 19984 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http) 2017-07-21 16:18:37.919 INFO 19984 --- [ main] com.xzh.demo.DemoApplication : Started DemoApplication in 2.324 seconds (JVM running for 2.719) 2017-07-21 16:18:41.874 INFO 19984 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring FrameworkServlet 'dispatcherServlet' 2017-07-21 16:18:41.874 INFO 19984 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization started 2017-07-21 16:18:41.883 INFO 19984 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization completed in 9 ms

 

5.访问http://localhost:8080/hello

 

参考：

Spring Boot 官方文档学习（一）入门及使用

Spring Boot学习

Spring Boot应用程序开发入门

Spring Boot快速入门

Spring Boot参考指南