Spring boot 是什么 ?
简单说, spring boot 是一个构建项目的工具, 一个脚手架.
Spring boot 能干什么?
spring boot 做非常少的配置就可以构建生产级别的单体应用.
Spring boot 怎么干的?
下面让我们来用spring boot 做一个hello world.
环境准备, 需要保证你的机器上已经有了如下软件
- JDK1.8+
- gradle4+
创建项目目录, 假设这个新的项目叫
apple.$ cd /tmp $ mkdir apple创建gradle配置文件,在这个目录下创建
build.gradle文件.$ cd apple $ vi build.gradle将如下代码复制到
build.gradle文件中.plugins {id 'org.springframework.boot' version '2.0.1.RELEASE' }apply plugin: 'java' apply plugin: 'io.spring.dependency-management'repositories {mavenCentral() }dependencies {compile 'org.springframework.boot:spring-boot-starter-web'testCompile 'org.springframework.boot:spring-boot-starter-test'testCompile 'org.springframework.boot:spring-boot-starter-webflux' }bootRun {main = 'com.thoughtworks.apple.Launcher' }写一个Hello world.
- 按照如下目录结构初始化项目内容
apple\-src\-main\-java\-com.thoughtworks.apple|-controller| \-HomeController.java\-Launcher.java- HomeController.java内容如下
package com.thoughtworks.apple.controller;import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController;@RestController public class HomeController {@RequestMapping("/")String home() {return "Hello World!";} }- Launcher.java内容如下
package com.thoughtworks.apple;import org.springframework.boot.SpringApplication; import org.springframework.boot.SpringBootConfiguration; import org.springframework.boot.autoconfigure.EnableAutoConfiguration; import org.springframework.context.annotation.ComponentScan;@SpringBootConfiguration @EnableAutoConfiguration @ComponentScan("com.thoughtworks.apple") public class Launcher {public static void main(String[] args) {SpringApplication.run(Launcher.class, args);} }运行
执行命令
gradle bootRun启动应用,之后会打印如下日志:$ gradle bootRun> Task :bootRun. ____ _ __ _ _/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\\/ ___)| |_)| | | | | || (_| | ) ) ) )' |____| .__|_| |_|_| |_\__, | / / / /=========|_|==============|___/=/_/_/_/:: Spring Boot :: (v2.0.1.RELEASE)2018-05-05 10:23:41.383 INFO 38941 --- [ main] com.thoughtworks.apple.Launcher : Starting Launcher on CNyfqi.local with PID 38941 (/private/tmp/apple/build/classes/java/main started by yfqi in /private/tmp/apple) 2018-05-05 10:23:41.386 INFO 38941 --- [ main] com.thoughtworks.apple.Launcher : No active profile set, falling back to default profiles: default 2018-05-05 10:23:41.432 INFO 38941 --- [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@3b2c72c2: startup date [Sat May 05 10:23:41 CST 2018]; root of context hierarchy 2018-05-05 10:23:42.289 INFO 38941 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http) 2018-05-05 10:23:42.313 INFO 38941 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2018-05-05 10:23:42.313 INFO 38941 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.29 2018-05-05 10:23:42.323 INFO 38941 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/Users/yfqi/Library/Java/Extensions:/Library/Java/Extensions:/Network/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java:.] 2018-05-05 10:23:42.402 INFO 38941 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2018-05-05 10:23:42.403 INFO 38941 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 973 ms 2018-05-05 10:23:42.522 INFO 38941 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/] 2018-05-05 10:23:42.525 INFO 38941 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2018-05-05 10:23:42.526 INFO 38941 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2018-05-05 10:23:42.526 INFO 38941 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*] 2018-05-05 10:23:42.526 INFO 38941 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*] 2018-05-05 10:23:42.627 INFO 38941 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2018-05-05 10:23:42.809 INFO 38941 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@3b2c72c2: startup date [Sat May 05 10:23:41 CST 2018]; root of context hierarchy 2018-05-05 10:23:42.878 INFO 38941 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto java.lang.String com.thoughtworks.apple.controller.HomeController.home() 2018-05-05 10:23:42.884 INFO 38941 --- [ 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.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest) 2018-05-05 10:23:42.885 INFO 38941 --- [ 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.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse) 2018-05-05 10:23:42.910 INFO 38941 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2018-05-05 10:23:42.910 INFO 38941 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2018-05-05 10:23:43.048 INFO 38941 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup 2018-05-05 10:23:43.100 INFO 38941 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path '' 2018-05-05 10:23:43.105 INFO 38941 --- [ main] com.thoughtworks.apple.Launcher : Started Launcher in 2.148 seconds (JVM running for 2.523) 2018-05-05 10:24:03.416 INFO 38941 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring FrameworkServlet 'dispatcherServlet' 2018-05-05 10:24:03.416 INFO 38941 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization started 2018-05-05 10:24:03.436 INFO 38941 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization completed in 20 ms <=========----> 75% EXECUTING [1m 28s] > :bootRun之后在浏览器中访问
http://localhost:8080/能看到如下页面说明程序运行成功了.
进阶
如何将gradle命令引入项目
当我们本地有多个项目, 且每个项目的gradle版本不一样时, 我们就需要把gradle命令保存在项目内, 然后每个项目用自己的gradle来构建. 下面这个命令可以直接初始化引入一个gradle命令到项目内部.
$ gradle wrapper --gradle-version 4.0之后项目目录下会多出四个文件
drwxr-xr-x 4 yfqi wheel 128 May 5 10:49 .gradle
drwxr-xr-x 3 yfqi wheel 96 May 5 10:49 gradle
-rwxr-xr-x 1 yfqi wheel 5296 May 5 10:49 gradlew
-rw-r--r-- 1 yfqi wheel 2260 May 5 10:49 gradlew.bat以后就可以在项目根目录下执行 ./gradlew来运行gradle的tasks了.
测试Hello World
程序成功运行了, 让我们来写一个测试用例测试一下hello world.
测试目录结构如下
apple\-src|-main \-test\-java\-com.thoughtworks.apple.controller\-HomeControllerTest.javaHomeControllerTest.java内容如下
package com.thoughtworks.apple.controller;import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.test.context.junit4.SpringRunner; import org.springframework.test.web.reactive.server.WebTestClient;@RunWith(SpringRunner.class) @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT) public class HomeControllerTest {@Autowiredprivate WebTestClient webClient;@Testpublic void should_get_home() {this.webClient.get().uri("/").exchange().expectStatus().isOk().expectBody(String.class).isEqualTo("Hello World!");} }运行测试使用命令
./gradlew test能看到如下日志说明测试执行成功$ gradle test Starting a Gradle Daemon (subsequent builds will be faster)> Task :test 2018-05-05 10:36:18.034 INFO 39291 --- [ Thread-6] ConfigServletWebServerApplicationContext : Closing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@918accb: startup date [Sat May 05 10:36:15 CST 2018]; root of context hierarchyBUILD SUCCESSFUL in 12s 3 actionable tasks: 3 executed
打包部署
- 执行命令
./grdlew bootJar来打包spring boot项目. 命令执行成功后会在apple/build/libs下多出一个jar包apple.jar.这就打包成功了. - 把打包好的jar包复制到运行的服务器, 执行命令
java -jar apple.jar &就可以把应用启动起来.
Spring Boot Starters
上面的例子大家会发现项目只是依赖了三个Spring Boot的Starter就完成了对所有第三方jar包的引用.Starter其实就是对第三方jar包依赖按照业务需要做了一个聚合,Spring Boot提供了大量的Starter来帮助开发人员快速开始构建项目, 降低了开发人员调包依赖的工作量.在这两个地址可以查看Spring Boot的所有的Starters.
- https://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/#using-boot-starter
- https://github.com/spring-projects/spring-boot/tree/master/spring-boot-project/spring-boot-starters
源码
文章的完整代码可以在这里找到: https://github.com/qyf404/learning-spring-boot
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