spring-boo hello world程序

Posted 2020-09-28 业余草

作为一个程序猿，使用了spring好多年，现在有了spring-boot，也想尝尝鲜。

初听spring-boot，觉得很神秘，实际上就是集合了很多组件，再加上一些boot开发的启动和粘合程序。 个人见解，不一定对。

构建过程

使用 Spring Initializr ，我使用idea构建的，在新项目里面有一个Spring Initializr 选项，如图：

设置项目属性，如图：

选择spring-boot组件： 

设置项目名： 

完成就可以了

第一个程序

新建Java程序

package com.sun.boot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.web.bind.annotation.*;

@RestController
@EnableAutoConfiguration
public class Application {

    @RequestMapping("/helloworld")
    public String home() {
        return "Hello World!";
    }
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

查看build.gradle文件

buildscript {
    ext {
        springBootVersion = \'1.5.4.RELEASE\'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: \'java\'
apply plugin: \'eclipse\'
apply plugin: \'org.springframework.boot\'

version = \'0.0.1-SNAPSHOT\'
sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    compile(\'org.springframework.boot:spring-boot-starter-web\')
    runtime(\'mysql:mysql-connector-java\')
    testCompile(\'org.springframework.boot:spring-boot-starter-test\')
}

程序结构如下： 

运行

运行Application，输出如下：

  .   ____          _            __ _ _
 /\\\\ / ___\'_ __ _ _(_)_ __  __ _ \\ \\ \\ \\
( ( )\\___ | \'_ | \'_| | \'_ \\/ _` | \\ \\ \\ \\
 \\\\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  \'  |____| .__|_| |_|_| |_\\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.4.RELEASE)

2017-07-19 08:22:36.552  INFO 8372 --- [           main] com.sun.boot.Application                 : Starting Application on sunzuoquan-Inspiron-7466 with PID 8372 (/home/sunzuoquan/IdeaProjects/demo/build/classes/java/main started by sunzuoquan in /home/sunzuoquan/IdeaProjects/demo)
2017-07-19 08:22:36.583  INFO 8372 --- [           main] com.sun.boot.Application                 : No active profile set, falling back to default profiles: default
2017-07-19 08:22:37.041  INFO 8372 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@43bd930a: startup date [Wed Jul 19 08:22:36 CST 2017]; root of context hierarchy
2017-07-19 08:22:42.185  INFO 8372 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2017-07-19 08:22:42.210  INFO 8372 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2017-07-19 08:22:42.211  INFO 8372 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.15
2017-07-19 08:22:42.747  INFO 8372 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2017-07-19 08:22:42.748  INFO 8372 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 5760 ms
2017-07-19 08:22:42.877  INFO 8372 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: \'dispatcherServlet\' to [/]
2017-07-19 08:22:42.880  INFO 8372 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: \'characterEncodingFilter\' to: [/*]
2017-07-19 08:22:42.880  INFO 8372 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: \'hiddenHttpMethodFilter\' to: [/*]
2017-07-19 08:22:42.880  INFO 8372 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: \'httpPutFormContentFilter\' to: [/*]
2017-07-19 08:22:42.881  INFO 8372 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: \'requestContextFilter\' to: [/*]
2017-07-19 08:22:43.338  INFO 8372 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@43bd930a: startup date [Wed Jul 19 08:22:36 CST 2017]; root of context hierarchy
2017-07-19 08:22:43.401  INFO 8372 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/helloworld]}" onto public java.lang.String com.sun.boot.Application.home()
2017-07-19 08:22:43.405  INFO 8372 --- [           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)
2017-07-19 08:22:43.405  INFO 8372 --- [           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)
2017-07-19 08:22:43.421  INFO 8372 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-07-19 08:22:43.421  INFO 8372 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-07-19 08:22:43.440  INFO 8372 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-07-19 08:22:43.634  INFO 8372 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2017-07-19 08:22:44.043  INFO 8372 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2017-07-19 08:22:44.065  INFO 8372 --- [           main] com.sun.boot.Application                 : Started Application in 9.217 seconds (JVM running for 15.872)

从日志可以看出，Tomcat started on port(s): 8080，spring-boot内部启动了tomcat，监听8080端口。
打开浏览器，访问：http://localhost:8080/helloworld
浏览器输出如下：