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spring boot学习总结(一)-- 基础入门 Hello,spring boot!

2017-07-22 21:30 681 查看

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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