一、引言
什么是 spring boot?
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。用我的话来理解，就是 spring boot 其实不是什么新的框架，它默认配置了很多框架的使用方式，就像 maven 整合了所有的 jar 包，spring boot 整合了所有的框架（不知道这样比喻是否合适）。
使用 spring boot 有什么好处？
其实就是简单、快速、方便！平时如果我们需要搭建一个 spring web 项目的时候需要怎么做呢？
配置完成之后部署 tomcat 调试
...
但是如果使用 spring boot 呢？
很简单，我仅仅只需要非常少的几个配置就可以迅速方便的搭建起来一套 web 项目或者是构建一个微服务！
使用 sping boot 是不是很爽，不信，接下来往下看！
二、基础环境准备
(以 Spring Boot 2.1.0.BUILD-SNAPSHOT 版本搭建)
1、JDK 环境安装
C:\Users\Administrator><strong><span style="color:#ff0000;">java -version</span></strong>java version "1.8.0_121"Java(TM) SE Runtime Environment (build 1.8.0_121-b13)Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)
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2、Maven 安装
Spring Boot 与 Apache Maven 3.2 或更高版本兼容。如果您尚未安装 Maven，则可以按照maven.apache.org上的说明进行操作。
(对于为何要安装 Maven，请自行查阅 Maven 相关资料)
三、创建 SpringBoot 项目
开发工具：Eclipse Jee Oxygen(v4.7.0)
1、创建 Maven 工程
2、创建 pom.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.xcbeyond</groupId> <artifactId>springboot</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>springboot</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.0.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> <spring-cloud.version>Finchley.M9</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>${spring-cloud.version}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> <repositories> <repository> <id>spring-milestones</id> <name>Spring Milestones</name> <url>https://repo.spring.io/milestone</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> </project>
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注：可以利用 eclipse 打开 pom.xml 图形界面方式添加依赖包。
3、编写代码
(1)、SpringBoot 启动类
新建 SpringbootApplication.java 文件，如下：
package com.xcbeyond.springboot; import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;/** * SpringBoot启动类 * @author xcbeyond * 2018年7月2日下午5:41:45 */@SpringBootApplicationpublic class SpringbootApplication { public static void main(String[] args) { SpringApplication.run(SpringbootApplication.class, args); }}
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注：注解 @SpringBootApplication，稍后会有章节详细说明。
（2）Controller
新建 ControllerDemo.java，如下：
package com.xcbeyond.springboot.controller; import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;/** * Controller demo * @author xcbeyond * 2018年7月5日下午11:22:49 */ @RestControllerpublic class ControllerDemo { @RequestMapping("/print") public String print() { return "hello SpringBoot!"; }}
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说明：
@RestController 的意思就是 controller 里面的方法都以 json 格式输出，不用再写什么配置！
四、运行 SpringBoot 工程
（1）启动。
直接运行上述的 SpringbootApplication 类即可，启动后可以看到类似于如下日志输出：
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v2.0.0.RELEASE) 2018-07-05 23:02:49.681 INFO 8932 --- [ main] c.x.springboot.SpringbootApplication : Starting SpringbootApplication on xcbeyond with PID 8932 (E:\micro-service\micro-service\springboot\target\classes started by Administrator in E:\micro-service\micro-service\springboot)2018-07-05 23:02:49.687 INFO 8932 --- [ main] c.x.springboot.SpringbootApplication : No active profile set, falling back to default profiles: default2018-07-05 23:02:49.767 INFO 8932 --- [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@4c40b76e: startup date [Thu Jul 05 23:02:49 CST 2018]; root of context hierarchy2018-07-05 23:02:51.628 INFO 8932 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)2018-07-05 23:02:51.655 INFO 8932 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]2018-07-05 23:02:51.655 INFO 8932 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.282018-07-05 23:02:51.679 INFO 8932 --- [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: [C:\Program Files\Java\jre1.8.0_171\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:/Program Files/Java/jre1.8.0_171/bin/server;C:/Program Files/Java/jre1.8.0_171/bin;C:/Program Files/Java/jre1.8.0_171/lib/amd64;C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Java\jdk1.7.0_79\bin;C:\Program Files\Git\cmd;C:\Program Files\TortoiseGit\bin;C:\Users\Administrator\AppData\Local\Microsoft\WindowsApps;;C:\Users\Administrator\Desktop\eclipse-jee-oxygen-R-win32-x86_64\eclipse;;.]2018-07-05 23:02:51.895 INFO 8932 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext2018-07-05 23:02:51.895 INFO 8932 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 2134 ms2018-07-05 23:02:52.084 INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/]2018-07-05 23:02:52.091 INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]2018-07-05 23:02:52.092 INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]2018-07-05 23:02:52.093 INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]2018-07-05 23:02:52.093 INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]2018-07-05 23:02:52.534 INFO 8932 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@4c40b76e: startup date [Thu Jul 05 23:02:49 CST 2018]; root of context hierarchy2018-07-05 23:02:52.634 INFO 8932 --- [ main] 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)2018-07-05 23:02:52.637 INFO 8932 --- [ 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.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)2018-07-05 23:02:52.685 INFO 8932 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2018-07-05 23:02:52.685 INFO 8932 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2018-07-05 23:02:52.732 INFO 8932 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2018-07-05 23:02:52.958 INFO 8932 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup2018-07-05 23:02:53.111 INFO 8932 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''2018-07-05 23:02:53.120 INFO 8932 --- [ main] c.x.springboot.SpringbootApplication : Started SpringbootApplication in 3.981 seconds (JVM running for 5.608)
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（2）测试。
在浏览器中输入 http://localhost:8080/print，则会如下正常显示，就说明已经 OK 啦，帅不帅！
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