学习Spring Boot

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.

  1. 环境准备, 需要保证你的机器上已经有了如下软件

    • JDK1.8+
    • gradle4+

  2. 创建项目目录, 假设这个新的项目叫apple.

    $ cd /tmp
$ mkdir apple

  3. 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'
}

  4. 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);
    }
}

  5. 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.java

  • HomeControllerTest.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 {
    @Autowired
    private WebTestClient webClient;

    @Test
    public 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 hierarchy


BUILD SUCCESSFUL in 12s
3 actionable tasks: 3 executed

打包部署

  1. 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.
  2. 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.

源码

文章的完整代码可以在这里找到: https://github.com/qyf404/learning-spring-boot

关于作者

posted @ 2018-05-05 20:05  辵鵵  阅读(875)  评论(0)  编辑  收藏  举报