spring boot学习总结（一）-- 基础入门 Hello,spring boot!
写在最前
SpringBoot是伴随着Spring4.0诞生的；
从字面理解，Boot是引导的意思，因此SpringBoot帮助开发者快速搭建Spring框架；
SpringBoot帮助开发者快速启动一个Web容器；
SpringBoot继承了原有Spring框架的优秀基因；
SpringBoot简化了使用Spring的过程。
SpringBoot使编码变简单，使配置变简单，使部署变简单，使监控变简单
下面正式开始！！！快速入门！！！
1、构建Maven项目
（1）访问 http://start.spring.io/，填写信息，选择版本
（2）点击 Switch to the full version
（3）选择适合的 Java Version
（4）点击 Generate Project，下载项目，可以得到项目压缩包
（5）解压项目压缩包，然后Import
完整的项目结构（除了controller包是下面第2步手动建的之外，其他都是下载后就有的）
打开pom.xml，可以看到下列代码
<?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.lmei</groupId> <artifactId>SpringBoot01</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <name>SpringBoot01</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.4.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>1.7</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> <scope>provided</scope> </dependency>
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
Import项目后，如果pom.xml报错，重新保存，让它重新加载。
加载成功后，pom.xml不再报错，但项目报错“Could not calculate build plan..."
右键项目->Maven->Update Project Configuration
2、测试
新建一个HelloController.java
package com.lmei.SpringBoot01.controller; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.EnableAutoConfiguration; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.ResponseBody; @Controller @EnableAutoConfiguration public class HelloController { @RequestMapping("/hello") @ResponseBody public String home() { return "Hello ,spring boot!"; } public static void main(String[] args) throws Exception { SpringApplication.run(HelloController.class, args); //运行之后在浏览器中访问：http://localhost:8080/hello } }
运行，HelloController右键->Run As->Java Application
控制台输出：
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v1.5.4.RELEASE) 2017-07-22 20:10:59.840 INFO 6484 --- [ main] c.l.S.controller.HelloController : Starting HelloController on USER-PC with PID 6484 (D:\workspace_spring\SpringBoot01\target\classes started by USER in D:\workspace_spring\SpringBoot01) 2017-07-22 20:10:59.840 INFO 6484 --- [ main] c.l.S.controller.HelloController : No active profile set, falling back to default profiles: default 2017-07-22 20:10:59.902 INFO 6484 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@524b19: startup date [Sat Jul 22 20:10:59 CST 2017]; root of context hierarchy 2017-07-22 20:11:01.961 INFO 6484 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http) 2017-07-22 20:11:01.977 INFO 6484 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2017-07-22 20:11:01.977 INFO 6484 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.15 2017-07-22 20:11:02.196 INFO 6484 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2017-07-22 20:11:02.196 INFO 6484 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 2294 ms 2017-07-22 20:11:02.446 INFO 6484 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/] 2017-07-22 20:11:02.462 INFO 6484 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2017-07-22 20:11:02.462 INFO 6484 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2017-07-22 20:11:02.462 INFO 6484 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*] 2017-07-22 20:11:02.462 INFO 6484 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*] 2017-07-22 20:11:02.898 INFO 6484 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@524b19: startup date [Sat Jul 22 20:10:59 CST 2017]; root of context hierarchy 2017-07-22 20:11:03.008 INFO 6484 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello]}" onto java.lang.String com.lmei.SpringBoot01.controller.HelloController.home() 2017-07-22 20:11:03.008 INFO 6484 --- [ 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) 2017-07-22 20:11:03.008 INFO 6484 --- [ 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) 2017-07-22 20:11:03.071 INFO 6484 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2017-07-22 20:11:03.071 INFO 6484 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2017-07-22 20:11:03.133 INFO 6484 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2017-07-22 20:11:03.352 INFO 6484 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup 2017-07-22 20:11:03.445 INFO 6484 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http) 2017-07-22 20:11:03.445 INFO 6484 --- [ main] c.l.S.controller.HelloController : Started HelloController in 4.137 seconds (JVM running for 4.651) 2017-07-22 20:14:39.768 INFO 6484 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring FrameworkServlet 'dispatcherServlet' 2017-07-22 20:14:39.769 INFO 6484 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization started 2017-07-22 20:14:39.819 INFO 6484 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization completed in 50 ms
然后在浏览器访问：http://localhost:8080/hello
运行时，可能会出现的错误
unable to start embedded container; nested exception is java.lang.NoSuchMethodError:
org.apache.tomcat.util.scan.StandardJarScanner.setJarScanFilter(Lorg/apache/tomcat/JarScanFilter;
完整的错误信息如下：
org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is java.lang.NoSuchMethodError: org.apache.tomcat.util.scan.StandardJarScanner.setJarScanFilter(Lorg/apache/tomcat/JarScanFilter;)V at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:137) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537) ~[spring-context-4.3.9.RELEASE.jar:4.3.9.RELEASE] at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at com.lmei.SpringBoot01.controller.HelloController.main(HelloController.java:20) [classes/:na] Caused by: java.lang.NoSuchMethodError: org.apache.tomcat.util.scan.StandardJarScanner.setJarScanFilter(Lorg/apache/tomcat/JarScanFilter;)V at org.springframework.boot.context.embedded.tomcat.SkipPatternJarScanner$Tomcat8TldSkipSetter.setSkipPattern(SkipPatternJarScanner.java:106) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.context.embedded.tomcat.SkipPatternJarScanner.setPatternToTomcat8SkipFilter(SkipPatternJarScanner.java:61) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.context.embedded.tomcat.SkipPatternJarScanner.<init>(SkipPatternJarScanner.java:56) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.context.embedded.tomcat.SkipPatternJarScanner.apply(SkipPatternJarScanner.java:87) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.prepareContext(TomcatEmbeddedServletContainerFactory.java:209) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.getEmbeddedServletContainer(TomcatEmbeddedServletContainerFactory.java:178) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:164) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:134) ~[spring-boot-1.5.4.RELEASE.jar:1.5.4.RELEASE] ... 8 common frames omitted
出错的原因是因为配置的时候不小心把tomcat配置进去，去掉就可以
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