學習Spring Boot

時間  2019-11-07
標籤 學習 spring boot 欄目 Spring 简体版
原文   原文鏈接

Spring boot 是什麼 ?

簡單說, spring boot 是一個構建項目的工具, 一個腳手架.html

Spring boot 能幹什麼?

spring boot 作很是少的配置就能夠構建生產級別的單體應用.java

Spring boot 怎麼幹的?

下面讓咱們來用spring boot 作一個hello world.react

  1. 環境準備, 須要保證你的機器上已經有了以下軟件git

    • JDK1.8+
    • gradle4+

  2. 建立項目目錄, 假設這個新的項目叫apple.github

    $ cd /tmp
$ mkdir apple

  3. 建立gradle配置文件,在這個目錄下建立build.gradle文件.web

    $ cd apple
$ vi build.gradle

    將以下代碼複製到build.gradle文件中.spring

    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. 寫一個Hello world.apache

    • 按照以下目錄結構初始化項目內容
    apple
  \-src
     \-main
       \-java
          \-com.thoughtworks.apple
              |-controller
              |   \-HomeController.java
              \-Launcher.java
    • HomeController.java內容以下
    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內容以下
    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. 運行瀏覽器

    執行命令gradle bootRun啓動應用,以後會打印以下日誌:tomcat

    $ 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

    以後在瀏覽器中訪問http://localhost:8080/ 能看到以下頁面說明程序運行成功了.

進階

如何將gradle命令引入項目

當咱們本地有多個項目, 且每一個項目的gradle版本不同時, 咱們就須要把gradle命令保存在項目內, 而後每一個項目用本身的gradle來構建. 下面這個命令能夠直接初始化引入一個gradle命令到項目內部.

$ gradle wrapper --gradle-version 4.0

以後項目目錄下會多出四個文件

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

之後就能夠在項目根目錄下執行 ./gradlew來運行gradle的tasks了.

測試Hello World

程序成功運行了, 讓咱們來寫一個測試用例測試一下hello world.

  • 測試目錄結構以下

    apple
  \-src
     |-main   
     \-test
        \-java
            \-com.thoughtworks.apple.controller
               \-HomeControllerTest.java

  • HomeControllerTest.java內容以下

    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!");
    }
}

  • 運行測試使用命令./gradlew test能看到以下日誌說明測試執行成功

    $ 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. 執行命令./grdlew bootJar來打包spring boot項目. 命令執行成功後會在apple/build/libs下多出一個jar包apple.jar.這就打包成功了.
  2. 把打包好的jar包複製到運行的服務器, 執行命令java -jar apple.jar &就能夠把應用啓動起來.

Spring Boot Starters

上面的例子你們會發現項目只是依賴了三個Spring Boot的Starter就完成了對全部第三方jar包的引用.Starter其實就是對第三方jar包依賴按照業務須要作了一個聚合,Spring Boot提供了大量的Starter來幫助開發人員快速開始構建項目, 下降了開發人員調包依賴的工做量.在這兩個地址能夠查看Spring Boot的全部的Starters.

源碼

文章的完整代碼能夠在這裏找到: https://github.com/qyf404/learning-spring-boot

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