• 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_springSpringBoot01	argetclasses started by USER in D:workspace_springSpringBoot01)
    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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  • 原文地址:https://www.cnblogs.com/lmei/p/7222892.html
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