SpringBoot 第一篇入门

一，第一步创建Maven工程，步骤如下

二，pom文件添加SpringBoot 依赖，我们第一次实例演示web 所以一并添加web starter：

<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.springboot.webdemo</groupId><artifactId>FirstDemo</artifactId><version>0.0.1-SNAPSHOT</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.5.13.RELEASE</version><relativePath /></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency></dependencies>
</project>

3，主要文件内容：

创建启动类SpringbootApplication：

package com.springboot;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class SpringbootApplication {public static void main(String[] args){SpringApplication.run(SpringbootApplication.class, args);}
}

创建Controller 类：

package com.springboot.controller;import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
public class FirstController {@GetMapping("/helloWord")public String helloWord(){return "hello Word";}
}

在jsrc/mian/resource下创建SpringBoot配置文件application.properties

server.port=8080

项目目录结构：

├─src
│  │  
│  ├─main
│  │  ├─java
│  │  │  └─com
│  │  │      └─springboot
│  │  │          │  SpringbootApplication.java
│  │  │          │  
│  │  │          └─controller
│  │  │                  FirstController.java
│  │  │                  
│  │  └─resources
│  │          application.properties
│  │          
│  └─test
│      ├─java
│      └─resources
├─ pom.xml

4,启动SpringBoot 容器

在启动类文件上右键-》run as  => java application

打印日志如下：

  .   ____          _            __ _ _/\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\\/  ___)| |_)| | | | | || (_| |  ) ) ) )'  |____| .__|_| |_|_| |_\__, | / / / /=========|_|==============|___/=/_/_/_/:: Spring Boot ::        (v1.5.6.RELEASE)2018-05-22 22:07:57.992  INFO 84724 --- [           main] c.x.springboot.SpringbootApplication     : Starting SpringbootApplication on lenovo-PC with PID 84724 (F:\asiainfo\projectName\target\classes started by lenovo in F:\asiainfo\projectName)
2018-05-22 22:07:57.997  INFO 84724 --- [           main] c.x.springboot.SpringbootApplication     : No active profile set, falling back to default profiles: default
2018-05-22 22:07:58.074  INFO 84724 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@3439f68d: startup date [Tue May 22 22:07:58 CST 2018]; root of context hierarchy
2018-05-22 22:08:00.011  INFO 84724 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 9090 (http)
2018-05-22 22:08:00.022  INFO 84724 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-05-22 22:08:00.023  INFO 84724 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.16
2018-05-22 22:08:00.144  INFO 84724 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-05-22 22:08:00.144  INFO 84724 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2077 ms
2018-05-22 22:08:00.325  INFO 84724 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2018-05-22 22:08:00.331  INFO 84724 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-05-22 22:08:00.332  INFO 84724 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-05-22 22:08:00.332  INFO 84724 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-05-22 22:08:00.332  INFO 84724 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-05-22 22:08:00.716  INFO 84724 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@3439f68d: startup date [Tue May 22 22:07:58 CST 2018]; root of context hierarchy
2018-05-22 22:08:00.806  INFO 84724 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/helloWord],methods=[GET]}" onto public java.lang.String com.xiaohui.springboot.controller.TestController.helloWord()
2018-05-22 22:08:00.810  INFO 84724 --- [           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.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-05-22 22:08:00.810  INFO 84724 --- [           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)
2018-05-22 22:08:00.847  INFO 84724 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-05-22 22:08:00.847  INFO 84724 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-05-22 22:08:00.898  INFO 84724 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-05-22 22:08:01.099  INFO 84724 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-05-22 22:08:01.209  INFO 84724 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 9090 (http)
2018-05-22 22:08:01.215  INFO 84724 --- [           main] c.x.springboot.SpringbootApplication     : Started SpringbootApplication in 3.6 seconds (JVM running for 3.972)
2018-05-22 22:08:10.834  INFO 84724 --- [nio-9090-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring FrameworkServlet 'dispatcherServlet'
2018-05-22 22:08:10.835  INFO 84724 --- [nio-9090-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started
2018-05-22 22:08:10.858  INFO 84724 --- [nio-9090-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 23 ms

5，访问请求：http://127.0.0.1:8080/helloWorld

结果如图：

6，遇到的问题：

在启动的过程中有可能启动失败提示：Unable to start embedded container; nested exception is java.lang.NoSuchMethodError: org.apache.tomcat.util.scan.StandardJarScanner.setJarScanFilter

问题有可能为springBoot 与 tomcat容器中jar包冲突。移除掉tomcat的jar包就可以参考：链接