1. Spring Boot入门

发布时间：2020-12-15 01:15:05 所属栏目：大数据来源：网络整理

导读：1.Spring Boot简介 ?? 简化 Spring应用开发的一个框架 ?? 整个 Spring技术栈的一个大整合 ??J2EE开发的一站式解决方案优点： – 快速创建独立运行的Spring项目以及与主流框架集成 – 使用嵌入式的Servlet容器，应用无需打成WAR包 – starters自动依赖与版本

1.Spring Boot简介

??简化Spring应用开发的一个框架

??整个Spring技术栈的一个大整合

??J2EE开发的一站式解决方案

优点：

– 快速创建独立运行的Spring项目以及与主流框架集成

– 使用嵌入式的Servlet容器，应用无需打成WAR包 – starters自动依赖与版本控制

– 大量的自动配置，简化开发，也可修改默认值 – 无需配置XML，无代码生成，开箱即用

– 准生产环境的运行时应用监控

– 与云计算的天然集成

2.微服务

??提出者：martin fowler

微服务：架构风格（服务微化）

??一个应用应该是一组小型服务；可以通过HTTP的方式进行互通；

单体应用：ALL IN ONE

??微服务：每一个功能元素最终都是一个可独立替换和独立升级的软件单元；

??微服务文档：https://martinfowler.com/articles/microservices.html#MicroservicesAndSoa

3.环境准备

[1].JDK1.8

??Spring Boot 推荐jdk1.7及以上；

??java version "1.8.0_201"

C:WINDOWSsystem32>java -version

java version "1.8.0_201"

Java(TM) SE Runtime Environment (build 1.8.0_201-b09)

Java HotSpot(TM) 64-Bit Server VM (build 25.201-b09,mixed mode)

[2].Maven3.x

??maven 3.3以上版本；

??Apache Maven 3.3.9

C:WINDOWSsystem32>mvn -v

Apache Maven 3.3.9 (bb52d8502b132ec0a5a3f4c09453c07478323dc5; 2015-11-11T00:41:47+08:00)

Maven home: D:DevInstallapache-maven-3.3.9

Java version: 1.8.0_201,vendor: Oracle Corporation

Java home: D:Program FilesJavajdk1.8.0_201jre

Default locale: zh_CN,platform encoding: GBK

OS name: "windows 10",version: "10.0",arch: "amd64",family: "dos"

??Maven设置：给Maven的settings.xml配置文件的profiles标签添加

????</profile>

????-->

</activation>

<maven.compiler.source>1.8</maven.compiler.source>

<maven.compiler.target>1.8</maven.compiler.target>

<maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>

</properties>

</profile>

??</profiles>

[3].IDEA2017

??IntelliJ IDEA 2017.3.7 x64

??STS

[4].Spring Boot

??SpringBoot 1.5.9.RELEASE：1.5.9；

IDEA设置

(1).整合Maven

??Configure->settings

4.Spring Boot HelloWorld

??浏览器发送hello请求，服务器接受请求并处理，响应Hello World字符串；

[1].创建Maven工程

??SDK选择我们安装的JDK位置即可

[2].导入依赖spring Boot相关的依赖

????<parent>

????????<groupId>org.springframework.boot</groupId>

????????<artifactId>spring-boot-starter-parent</artifactId>

????????<version>1.5.9.RELEASE</version>

????</parent>

????<dependencies>

????????<dependency>

????????????<groupId>org.springframework.boot</groupId>

????????????<artifactId>spring-boot-starter-web</artifactId>

????????</dependency>

????</dependencies>

[3].编写主程序main

/**

?* ?@SpringBootApplication 来标注一个主程序类，说明这是一个Spring Boot应用

?*/

@SpringBootApplication

public class HelloWorldMainApplication {

????public static void main(String[] args) {

????????// Spring应用启动起来

????????SpringApplication.run(HelloWorldMainApplication.class,args);

????}

}

[4].编写Controller、Service

@Controller

public class HelloController {

????@ResponseBody

????@RequestMapping("/hello")

????public String hello(){

????????return "Hello World!";

????}

}

[5].运行主程序测试

[6].简化部署

??将这个应用打成jar包，直接使用java -jar的命令进行执行；

????

????<build>

????????<plugins>

????????????<plugin>

????????????????<groupId>org.springframework.boot</groupId>

????????????????<artifactId>spring-boot-maven-plugin</artifactId>

????????????</plugin>

????????</plugins>

????</build>

5.HelloWorld解析

[1].POM文件

(1).父项目

????<parent>

????????<groupId>org.springframework.boot</groupId>

????????<artifactId>spring-boot-starter-parent</artifactId>

????????<version>1.5.9.RELEASE</version>

????</parent>

它的父项目

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-dependencies</artifactId>

<version>1.5.9.RELEASE</version>

<relativePath>../../spring-boot-dependencies</relativePath>

</parent>

它是真正管理Spring Boot应用里面的所有依赖版本：

<activemq.version>5.14.5</activemq.version>

<antlr2.version>2.7.7</antlr2.version>

<appengine-sdk.version>1.9.59</appengine-sdk.version>

<artemis.version>1.5.5</artemis.version>

<aspectj.version>1.8.13</aspectj.version>

<assertj.version>2.6.0</assertj.version>

<atomikos.version>3.9.3</atomikos.version>

<bitronix.version>2.1.4</bitronix.version>

<caffeine.version>2.3.5</caffeine.version>

<cassandra-driver.version>3.1.4</cassandra-driver.version>

<classmate.version>1.3.4</classmate.version>

<commons-beanutils.version>1.9.3</commons-beanutils.version>

<commons-collections.version>3.2.2</commons-collections.version>

<commons-codec.version>1.10</commons-codec.version>

<commons-dbcp.version>1.4</commons-dbcp.version>

<commons-dbcp2.version>2.1.1</commons-dbcp2.version>

<commons-digester.version>2.1</commons-digester.version>

<commons-pool.version>1.6</commons-pool.version>

<commons-pool2.version>2.4.3</commons-pool2.version>

<couchbase-client.version>2.3.7</couchbase-client.version>

<couchbase-cache-client.version>2.1.0</couchbase-cache-client.version>

<crashub.version>1.3.2</crashub.version>

<derby.version>10.13.1.1</derby.version>

<dom4j.version>1.6.1</dom4j.version>

<dropwizard-metrics.version>3.1.5</dropwizard-metrics.version>

<ehcache.version>2.10.4</ehcache.version>

<ehcache3.version>3.2.3</ehcache3.version>

<embedded-mongo.version>1.50.5</embedded-mongo.version>

<flyway.version>3.2.1</flyway.version>

<freemarker.version>2.3.27-incubating</freemarker.version>

<elasticsearch.version>2.4.6</elasticsearch.version>

<gemfire.version>8.2.7</gemfire.version>

<glassfish-el.version>3.0.0</glassfish-el.version>

<gradle.version>2.9</gradle.version>

<groovy.version>2.4.13</groovy.version>

<gson.version>2.8.2</gson.version>

<h2.version>1.4.196</h2.version>

<hamcrest.version>1.3</hamcrest.version>

<hazelcast.version>3.7.8</hazelcast.version>

<hazelcast-hibernate4.version>3.7.1</hazelcast-hibernate4.version>

<hazelcast-hibernate5.version>1.1.3</hazelcast-hibernate5.version>

<hibernate.version>5.0.12.Final</hibernate.version>

<hibernate-validator.version>5.3.6.Final</hibernate-validator.version>

<hikaricp.version>2.5.1</hikaricp.version>

<hikaricp-java6.version>2.3.13</hikaricp-java6.version>

<hikaricp-java7.version>2.4.13</hikaricp-java7.version>

<hsqldb.version>2.3.5</hsqldb.version>

<htmlunit.version>2.21</htmlunit.version>

<httpasyncclient.version>4.1.3</httpasyncclient.version>

<httpclient.version>4.5.3</httpclient.version>

<httpcore.version>4.4.8</httpcore.version>

<infinispan.version>8.2.8.Final</infinispan.version>

<jackson.version>2.8.10</jackson.version>

<janino.version>2.7.8</janino.version>

<javassist.version>3.21.0-GA</javassist.version>

<javax-cache.version>1.0.0</javax-cache.version>

<javax-mail.version>1.5.6</javax-mail.version>

<javax-transaction.version>1.2</javax-transaction.version>

<javax-validation.version>1.1.0.Final</javax-validation.version>

<jaxen.version>1.1.6</jaxen.version>

<jaybird.version>2.2.13</jaybird.version>

<jboss-logging.version>3.3.1.Final</jboss-logging.version>

<jboss-transaction-spi.version>7.6.0.Final</jboss-transaction-spi.version>

<jdom2.version>2.0.6</jdom2.version>

<jedis.version>2.9.0</jedis.version>

<jersey.version>2.25.1</jersey.version>

<jest.version>2.0.4</jest.version>

<jetty.version>9.4.7.v20170914</jetty.version>

<jetty-jsp.version>2.2.0.v201112011158</jetty-jsp.version>

<jetty-el.version>8.0.33</jetty-el.version>

<jms-api.version>1.1-rev-1</jms-api.version>

<jmustache.version>1.13</jmustache.version>

<jna.version>4.2.2</jna.version>

<joda-time.version>2.9.9</joda-time.version>

<jolokia.version>1.3.7</jolokia.version>

<jooq.version>3.9.6</jooq.version>

<json.version>20140107</json.version>

<jsonassert.version>1.4.0</jsonassert.version>

<json-path.version>2.2.0</json-path.version>

<jstl.version>1.2</jstl.version>

<jtds.version>1.3.1</jtds.version>

<junit.version>4.12</junit.version>

<liquibase.version>3.5.3</liquibase.version>

<log4j2.version>2.7</log4j2.version>

<logback.version>1.1.11</logback.version>

<lombok.version>1.16.18</lombok.version>

<mariadb.version>1.5.9</mariadb.version>

<mssql-jdbc.version>6.1.0.jre7</mssql-jdbc.version>

<mockito.version>1.10.19</mockito.version>

<mongodb.version>3.4.3</mongodb.version>

<mysql.version>5.1.44</mysql.version>

<narayana.version>5.5.30.Final</narayana.version>

<nekohtml.version>1.9.22</nekohtml.version>

<neo4j-ogm.version>2.1.5</neo4j-ogm.version>

<postgresql.version>9.4.1212.jre7</postgresql.version>

<querydsl.version>4.1.4</querydsl.version>

<reactor.version>2.0.8.RELEASE</reactor.version>

<reactor-spring.version>2.0.7.RELEASE</reactor-spring.version>

<selenium.version>2.53.1</selenium.version>

<selenium-htmlunit.version>2.21</selenium-htmlunit.version>

<sendgrid.version>2.2.2</sendgrid.version>

<servlet-api.version>3.1.0</servlet-api.version>

<simple-json.version>1.1.1</simple-json.version>

<slf4j.version>1.7.25</slf4j.version>

<snakeyaml.version>1.17</snakeyaml.version>

<solr.version>5.5.5</solr.version>

<spock.version>1.0-groovy-2.4</spock.version>

<spring.version>4.3.13.RELEASE</spring.version>

<spring-amqp.version>1.7.4.RELEASE</spring-amqp.version>

<spring-cloud-connectors.version>1.2.5.RELEASE</spring-cloud-connectors.version>

<spring-batch.version>3.0.8.RELEASE</spring-batch.version>

<spring-data-releasetrain.version>Ingalls-SR9</spring-data-releasetrain.version>

<spring-hateoas.version>0.23.0.RELEASE</spring-hateoas.version>

<spring-integration.version>4.3.12.RELEASE</spring-integration.version>

<spring-integration-java-dsl.version>1.2.3.RELEASE</spring-integration-java-dsl.version>

<spring-kafka.version>1.1.7.RELEASE</spring-kafka.version>

<spring-ldap.version>2.3.2.RELEASE</spring-ldap.version>

<spring-loaded.version>1.2.8.RELEASE</spring-loaded.version>

<spring-mobile.version>1.1.5.RELEASE</spring-mobile.version>

<spring-plugin.version>1.2.0.RELEASE</spring-plugin.version>

<spring-restdocs.version>1.1.3.RELEASE</spring-restdocs.version>

<spring-retry.version>1.2.1.RELEASE</spring-retry.version>

<spring-security.version>4.2.3.RELEASE</spring-security.version>

<spring-security-jwt.version>1.0.8.RELEASE</spring-security-jwt.version>

<spring-security-oauth.version>2.0.14.RELEASE</spring-security-oauth.version>

<spring-session.version>1.3.1.RELEASE</spring-session.version>

<spring-social.version>1.1.4.RELEASE</spring-social.version>

<spring-social-facebook.version>2.0.3.RELEASE</spring-social-facebook.version>

<spring-social-linkedin.version>1.0.2.RELEASE</spring-social-linkedin.version>

<spring-social-twitter.version>1.1.2.RELEASE</spring-social-twitter.version>

<spring-ws.version>2.4.2.RELEASE</spring-ws.version>

<sqlite-jdbc.version>3.15.1</sqlite-jdbc.version>

<statsd-client.version>3.1.0</statsd-client.version>

<sun-mail.version>${javax-mail.version}</sun-mail.version>

<thymeleaf.version>2.1.6.RELEASE</thymeleaf.version>

<thymeleaf-extras-springsecurity4.version>2.1.3.RELEASE</thymeleaf-extras-springsecurity4.version>

<thymeleaf-extras-conditionalcomments.version>2.1.2.RELEASE</thymeleaf-extras-conditionalcomments.version>

<thymeleaf-layout-dialect.version>1.4.0</thymeleaf-layout-dialect.version>

<thymeleaf-extras-data-attribute.version>1.3</thymeleaf-extras-data-attribute.version>

<thymeleaf-extras-java8time.version>2.1.0.RELEASE</thymeleaf-extras-java8time.version>

<tomcat.version>8.5.23</tomcat.version>

<undertow.version>1.4.21.Final</undertow.version>

<unboundid-ldapsdk.version>3.2.1</unboundid-ldapsdk.version>

<webjars-hal-browser.version>9f96c74</webjars-hal-browser.version>

<webjars-locator.version>0.32-1</webjars-locator.version>

<wsdl4j.version>1.6.3</wsdl4j.version>

<xml-apis.version>1.4.01</xml-apis.version>

<build-helper-maven-plugin.version>1.10</build-helper-maven-plugin.version>

<exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>

<git-commit-id-plugin.version>2.2.3</git-commit-id-plugin.version>

<maven-antrun-plugin.version>1.8</maven-antrun-plugin.version>

<maven-assembly-plugin.version>2.6</maven-assembly-plugin.version>

<maven-clean-plugin.version>2.6.1</maven-clean-plugin.version>

<maven-compiler-plugin.version>3.1</maven-compiler-plugin.version>

<maven-dependency-plugin.version>2.10</maven-dependency-plugin.version>

<maven-deploy-plugin.version>2.8.2</maven-deploy-plugin.version>

<maven-eclipse-plugin.version>2.10</maven-eclipse-plugin.version>

<maven-enforcer-plugin.version>1.4</maven-enforcer-plugin.version>

<maven-failsafe-plugin.version>2.18.1</maven-failsafe-plugin.version>

<maven-install-plugin.version>2.5.2</maven-install-plugin.version>

<maven-invoker-plugin.version>1.10</maven-invoker-plugin.version>

<maven-help-plugin.version>2.2</maven-help-plugin.version>

<maven-jar-plugin.version>2.6</maven-jar-plugin.version>

<maven-javadoc-plugin.version>2.10.4</maven-javadoc-plugin.version>

<maven-resources-plugin.version>2.7</maven-resources-plugin.version>

<maven-shade-plugin.version>2.4.3</maven-shade-plugin.version>

<maven-site-plugin.version>3.5.1</maven-site-plugin.version>

<maven-source-plugin.version>2.4</maven-source-plugin.version>

<maven-surefire-plugin.version>2.18.1</maven-surefire-plugin.version>

<maven-war-plugin.version>2.6</maven-war-plugin.version>

<versions-maven-plugin.version>2.2</versions-maven-plugin.version>

</properties>

??Spring Boot的版本中心；

??以后我们导入依赖默认是不需要写版本；（没有在dependencies里面管理的依赖自然需要声明版本号）

(2).启动器

????<dependencies>

????????<dependency>

????????????<groupId>org.springframework.boot</groupId>

????????????<artifactId>spring-boot-starter-web</artifactId>

????????</dependency>

????</dependencies>

??spring-boot-starter-web：Spring-boot场景启动器,帮我们导入了web模块正常运行所依赖的组件.

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-tomcat</artifactId>

</dependency>

<groupId>org.hibernate</groupId>

<artifactId>hibernate-validator</artifactId>

</dependency>

<groupId>com.fasterxml.jackson.core</groupId>

<artifactId>jackson-databind</artifactId>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-web</artifactId>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-webmvc</artifactId>

</dependency>

??Spring Boot将所有的功能场景都抽取出来，做成一个个的starters（启动器），只需要在项目里面引入这些starter相关场景的所有依赖都会导入进来。要用什么功能就导入什么场景的启动器

[2].主程序类(主入口类)

/**

?* @SpringBootApplication 来标注一个主程序类说明这是一个Spring boot应用

?*/

@SpringBootApplication

public class HelloWorldMainApplication {

????public static void main(String[] args) {

????????//Spring应用启动起来

????????SpringApplication.run(HelloWorldMainApplication.class,args);

????}

}

@SpringBootApplication: Spring Boot应用标注在某个类上说明这个类是SpringBoot的主配置类，SpringBoot就应该运行这个类的main方法来启动SpringBoot应用；

@Target(ElementType.TYPE)

@Retention(RetentionPolicy.RUNTIME)

@Documented

@Inherited

@SpringBootConfiguration

@EnableAutoConfiguration

@ComponentScan(excludeFilters = {

??????@Filter(type = FilterType.CUSTOM,classes = TypeExcludeFilter.class),

??????@Filter(type = FilterType.CUSTOM,classes = AutoConfigurationExcludeFilter.class) })

public @interface SpringBootApplication {

@SpringBootConfiguration：Spring Boot的配置类；

??标注在某个类上，表示这是一个Spring Boot的配置类

????|- @Configuration:配置类上来标注这个注解；

??????配置类 ----- ?配置文件；

???配置类也是容器中的一个组件；

??|- @Component

@EnableAutoConfiguration：开启自动配置功能；

??以前我们需要配置的东西，Spring Boot帮我们自动配置；@EnableAutoConfiguration告诉SpringBoot开启自动配置功能；这样自动配置才能生效；

@AutoConfigurationPackage

@Import(EnableAutoConfigurationImportSelector.class)

public @interface EnableAutoConfiguration {}

@AutoConfigurationPackage：自动配置包；

??|- @Import(AutoConfigurationPackages.Registrar.class)

????Spring的底层注解@Import，给容器中导入一个组件；导入的组件由AutoConfigurationPackages.Registrar.class；

?将主配置类（@SpringBootApplication标注的类）的所在包及下面所有子包里面的所有组件扫描到Spring容器；

????????public void registerBeanDefinitions(AnnotationMetadata metadata,BeanDefinitionRegistry registry) {

????????????AutoConfigurationPackages.register(registry,(new AutoConfigurationPackages.PackageImport(metadata)).getPackageName());

????????}

@Import({EnableAutoConfigurationImportSelector.class})：给容器中导入组件;

??|- EnableAutoConfigurationImportSelector:导入那些组件的选择器

????将所有需要导入的组件以全类名的方式返回；这些组件就会被添加到容器中；

????会给容器中导入非常多的自动配置类（xxxAutoConfiguration）；就是给容器中导入这个场景需要的所有组件，并配置好这些组件；

????public String[] selectImports(AnnotationMetadata annotationMetadata) {

????????if (!this.isEnabled(annotationMetadata)) {

????????????return NO_IMPORTS;

????????} else {

????????????try {

????????????????AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader.loadMetadata(this.beanClassLoader);

????????????????AnnotationAttributes attributes = this.getAttributes(annotationMetadata);

????????????????List<String> configurations = this.getCandidateConfigurations(annotationMetadata,attributes);

????????????????configurations = this.removeDuplicates(configurations);

????????????????configurations = this.sort(configurations,autoConfigurationMetadata);

????????????????Set<String> exclusions = this.getExclusions(annotationMetadata,attributes);

????????????????this.checkExcludedClasses(configurations,exclusions);

????????????????configurations.removeAll(exclusions);

????????????????configurations = this.filter(configurations,autoConfigurationMetadata);

????????????????this.fireAutoConfigurationImportEvents(configurations,exclusions);

????????????????return (String[])configurations.toArray(new String[configurations.size()]);

????????????} catch (IOException var6) {

????????????????throw new IllegalStateException(var6);

????????????}

????????}

????}

??有了自动配置类，免去了我们手动编写配置注入功能组件等的工作； ????

SpringFactoriesLoader.loadFactoryNames(EnableAutoConfiguration.class,classLoader)；

??Spring Boot在启动的时候从类路径下的META-INF/spring.factories中获取EnableAutoConfiguration指定的值，将这些值作为自动配置类导入到容器中，自动配置类就生效，帮我们进行自动配置工作；以前我们需要自己配置的东西，自动配置类都帮我们；

??J2EE的整体整合解决方案和自动配置都在spring-boot-autoconfigure-1.5.9.RELEASE.jar；

6.使用Spring Initializer快速创建Spring Boot项目

[1].IDEA：使用 Spring Initializer快速创建项目

IDE都支持使用Spring的项目创建向导快速创建一个Spring Boot项目；

选择我们需要的模块；向导会联网创建Spring Boot项目；

默认生成的Spring Boot项目；

- 主程序已经生成好了，我们只需要我们自己的逻辑

- resources文件夹中目录结构

??- static：保存所有的静态资源； js css ?images；

??- templates：保存所有的模板页面；（Spring Boot默认jar包使用嵌入式的Tomcat，默认不支持JSP页面）；可以使用模板引擎（freemarker、thymeleaf）；

??- application.properties：Spring Boot应用的配置文件；可以修改一些默认设置；

[2].STS使用Spring Starter Project快速创建项目

参考文档：https://docs.spring.io/spring-boot/docs/1.5.9.RELEASE/reference/htmlsingle/

（编辑：李大同）

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