先想一下，正常我们想要创建一个web服务，首先需要下载tomcat，创建web工程，配置各种web.xml，引入spring的配置，各种配置文件一顿倒腾.....下载有了spring boot，你创建一个web工程只需要一个java类，甚至都不需要下载tomcat，直接右键执行就能启动一个web服务。听起来就让人感觉兴奋！
最近我也是工作有需要，需要新建一个微服务的模块。正好公司比较开放，支持搞搞新技术，于是就在同事的怂恿下采用Spring Boot创建了一个工程。使用后发现如果熟练掌握一些配置的技巧，那么其实是事半功倍的。（当然你需要花点时间熟悉一下Spring Boot的流程）。不过创建这样一个工程真的是很简单，下面就先看看效果：
创建Hello world工程
安装jdk和maven
前提条件肯定是要安装jdk和maven，配置好环境变量，这个就不多说了:
xinghailong@DESKTOP-JB5HET6 MINGW64 ~/Documents/workspace/my$ java -versionjava version "1.8.0_66"Java(TM) SE Runtime Environment (build 1.8.0_66-b17)Java HotSpot(TM) 64-Bit Server VM (build 25.66-b17, mixed mode)xinghailong@DESKTOP-JB5HET6 MINGW64 ~/Documents/workspace/my$ mvn -versionApache Maven 3.3.9 (bb52d8502b132ec0a5a3f4c09453c07478323dc5; 2015-11-11T00:41:47+08:00)Maven home: C:\Users\xinghailong\Documents\soft\apache-maven-3.3.9Java version: 1.8.0_66, vendor: Oracle CorporationJava home: C:\Program Files\Java\jdk1.8.0_66\jreDefault locale: zh_CN, platform encoding: GBKOS name: "windows 10", version: "10.0", arch: "amd64", family: "dos"
然后配置maven依赖
4.0.0 xingoo SimpleSpringBoot 0.0.1-SNAPSHOT jar org.springframework.boot spring-boot-starter-parent 1.5.4.RELEASE org.springframework.boot spring-boot-starter-web src org.springframework.boot spring-boot-maven-plugin
最后创建一个java类
package main.java.xingoo;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.EnableAutoConfiguration;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;/** * Created by xinghailong on 2017/7/21. *//*@Configuration@EnableAutoConfiguration@ComponentScan*/@SpringBootApplicationpublic class Application { public static void main(String[] args) { SpringApplication.run(Application.class, args); }} 并且创建一个Controller（你也可以直接在上面的类中创建请求Mapping）
package main.java.xingoo.web;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;/** * Created by xinghailong on 2017/7/21. */@RestControllerpublic class TestController { @RequestMapping("/hello") public String hello(){ return "hello world!"; }} 在Application类上直接执行
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v1.5.4.RELEASE)2017-07-21 23:46:50.580 INFO 22236 --- [ main] main.java.xingoo.Application : Starting Application on DESKTOP-JB5HET6 with PID 22236 (C:\Users\xinghailong\Documents\workspace\my\SimpleSpringBoot\target\classes started by xinghailong in C:\Users\xinghailong\Documents\workspace\tiangou\code\workbench)2017-07-21 23:46:50.588 INFO 22236 --- [ main] main.java.xingoo.Application : No active profile set, falling back to default profiles: default2017-07-21 23:46:50.700 INFO 22236 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4da4253: startup date [Fri Jul 21 23:46:50 CST 2017]; root of context hierarchy2017-07-21 23:46:54.086 INFO 22236 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)2017-07-21 23:46:54.117 INFO 22236 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]2017-07-21 23:46:54.118 INFO 22236 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.152017-07-21 23:46:54.346 INFO 22236 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext2017-07-21 23:46:54.346 INFO 22236 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 3653 ms2017-07-21 23:46:54.684 INFO 22236 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]2017-07-21 23:46:54.713 INFO 22236 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]2017-07-21 23:46:54.715 INFO 22236 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]2017-07-21 23:46:54.717 INFO 22236 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]2017-07-21 23:46:54.717 INFO 22236 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]2017-07-21 23:46:55.302 INFO 22236 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4da4253: startup date [Fri Jul 21 23:46:50 CST 2017]; root of context hierarchy2017-07-21 23:46:55.472 INFO 22236 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello]}" onto public java.lang.String main.java.xingoo.web.TestController.hello()2017-07-21 23:46:55.480 INFO 22236 --- [ 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)2017-07-21 23:46:55.481 INFO 22236 --- [ 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)2017-07-21 23:46:55.564 INFO 22236 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2017-07-21 23:46:55.564 INFO 22236 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2017-07-21 23:46:55.632 INFO 22236 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2017-07-21 23:46:56.004 INFO 22236 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup2017-07-21 23:46:56.134 INFO 22236 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)2017-07-21 23:46:56.142 INFO 22236 --- [ main] main.java.xingoo.Application : Started Application in 6.834 seconds (JVM running for 8.969) 在页面访问localhost:8080/hello
就能看到输出信息了。
hello world!
很简单吧！
代码我已经上传到github上面，如果有兴趣的可以直接clone下来使用:https://github.com/xinghalo/SimpleSpringBoot.git
跟着官方文档学习下基本知识
关于注解@EnableAutoConfiguration
其他的内容就不说了，跟之前部署到tomcat差不多，不同的是多了这个注解，这个注解的作用是会去根据配置的pom依赖，自动加载一些类，比如数据库的dataSource等。
关于部署
SpringBoot的项目可以直接打成一个 可执行的jar包，即fat jar。一般情况下java是不支持内嵌jar的，它会在你打包的时候把class抽离出来放在一个jar里面，如果有两个class名称和目录都相同，那么就会出现冲突。因此Spring Boot提供了自己的打包插件，这就需要在build当中引入该plugin：
org.springframework.boot spring-boot-maven-plugin
然后，在pom.xml同层目录下，执行命令mvn clean package就可以打包了。
推荐的包层次
com +- example +- myproject +- Application.java | +- domain | +- Customer.java | +- CustomerRepository.java | +- service | +- CustomerService.java | +- web +- CustomerController.java
Configuration
在Spring Boot中，一般很少使用xml进行配置，都是基于Class来配置的。如果有一些配置项，那么可以把这个类加上注解@Configuration。如果额外需要引入xml，也可以使用注解@ImportResource添加xml文件
禁用某些配置
比如你的项目根本不需要引入数据库连接池，那么就可以使用exclude进行排除:
@Configuration@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})public class MyConfiguration {} 使用@SpringBootApplication
这个注解可以当做是@Configuration, @EnableAutoConfiguration and @ComponentScan的合体
使用maven启动
执行下面的命令，也可以通过maven启动spring boot
mvn spring-boot:run