史上最简单的SpringBoot教程之如何打印HelloWorld
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2022-04-22 13:38:52
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一、前言
Spring boot是由Pivotal团队提供的全新框架，其设计目的是用来简化新Spring应用的初始搭建以及开发过程。该框架使用了特定的方式来进行配置，从而使开发人员不再需要定义样板化的配置。
Spring boot包含的特性：
- 创建独立的Spring应用程序
- 嵌入Tomcat，无需部署war文件
- 简化Maven配置
- 自动配置Spring
- 提供生产就绪功能，如指标，健康检查和外部配置
- 开箱即用，没有代码生成，也无需XML配置
为基于Spring的开发提供更快的入门体验，开箱即用，没有代码生成，也无需XML配置。同时也可以修改默认值来满足特定需求。提供了一些大型项目中常见的非功能特性，如嵌入式服务器、安全、指标、健康体检、外部配置等。Spring boot并不是对Spring功能的增强，而是提供了一种快速使用Spring的方式。
二、准备
开发环境：1.7.0_79
开发工具：Eclipse
项目管理工具：Maven3
操作系统：Windows8
Spring boot版本：1.4.1.RELEASE
三、案例
搭建一个Maven工程SpringBootHelloWorld
POM文件中导入相关依赖
<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.queen.springboot</groupId>
<artifactId>SpringBootHelloWorld</artifactId>
<version>0.0.1-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.1.RELEASE</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.7</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
</project>环境中我们指定JDK的版本为1.7，默认是1.6
导入spring-boot-starter-web依赖这个地方我们没有指定版本号，是因为上面我们配置了parent，所以不用添加了。
编写控制类SpringBootHelloWorld
@RestController
public class HelloWorldController {
@RequestMapping("/hello")
public String sayHello() {
return "helloWorld";
}
}这里我们使用的@RestController注解等价于@Controller和@ResponseBody注解，使用@RequestMapping建立请求映射。
编写启动类APP
@SpringBootApplication
public class APP {
public static void main(String[] args) {
SpringApplication.run(APP.class, args);
}
}使用@SpringBootApplication注解定义APP是一个SpringBoot类型的应用，在main方法中使用SpringApplication的run方法启动我们的程序。
右键Run As -> Java Application，启动应用，控制台启动日志如下：
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v1.4.1.RELEASE)
2017-07-16 10:31:07.706 INFO 12108 --- [ main] com.queen.controller.APP : Starting APP on Lenovo-PC with PID 12108 (E:\queen\SpringBootHelloWorld\target\classes started by think in E:\queen\SpringBootHelloWorld)
2017-07-16 10:31:07.709 INFO 12108 --- [ main] com.queen.controller.APP : No active profile set, falling back to default profiles: default
2017-07-16 10:31:07.814 INFO 12108 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot[email protected]6568614: startup date [Sun Jul 16 10:31:07 CST 2017]; root of context hierarchy
2017-07-16 10:31:10.086 INFO 12108 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2017-07-16 10:31:10.099 INFO 12108 --- [ main] o.apache.catalina.core.StandardService : Starting service Tomcat
2017-07-16 10:31:10.101 INFO 12108 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.5
2017-07-16 10:31:10.201 INFO 12108 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2017-07-16 10:31:10.202 INFO 12108 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 2392 ms
2017-07-16 10:31:10.411 INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]
2017-07-16 10:31:10.415 INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2017-07-16 10:31:10.417 INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2017-07-16 10:31:10.417 INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2017-07-16 10:31:10.417 INFO 12108 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2017-07-16 10:31:10.812 INFO 12108 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot[email protected]6568614: startup date [Sun Jul 16 10:31:07 CST 2017]; root of context hierarchy
2017-07-16 10:31:10.906 INFO 12108 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello]}" onto public java.lang.String com.queen.controller.HelloWorldController.sayHello()
2017-07-16 10:31:10.913 INFO 12108 --- [ 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)
2017-07-16 10:31:10.913 INFO 12108 --- [ 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)
2017-07-16 10:31:10.965 INFO 12108 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-07-16 10:31:10.966 INFO 12108 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-07-16 10:31:11.013 INFO 12108 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-07-16 10:31:11.320 INFO 12108 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2017-07-16 10:31:11.391 INFO 12108 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2017-07-16 10:31:11.398 INFO 12108 --- [ main] com.queen.controller.APP : Started APP in 4.301 seconds (JVM running for 4.619)♦使用http://localhost:8080/hello看是否能够访问我们的应用
访问成功。
至此，我们使用Spring boot搭建的第一个HelloWorld小程序完成。
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