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SpringBoot Starter介绍以及实例

热度:96   发布时间:2023-09-07 04:05:58

一.Spring Boot Starter简介

Starter是Spring Boot中的一个非常重要的概念,Starter相当于模块,它能将模块所需的依赖整合起来并对模块内的Bean根据环境( 条件)进行自动配置。使用者只需要依赖相应功能的Starter,无需做过多的配置和依赖,Spring Boot就能自动扫描并加载相应的模块。

例如在Maven的依赖中加入spring-boot-starter-web就能使项目支持Spring MVC,并且Spring Boot还为我们做了很多默认配置,无需再依赖spring-web、spring-webmvc等相关包及做相关配置就能够立即使用起来。

二.Starter的开发步骤

编写Starter非常简单,与编写一个普通的Spring Boot应用没有太大区别,总结如下:

1.新建Maven项目,在项目的POM文件中定义使用的依赖;
2.新建配置类,写好配置项和默认的配置值,指明配置项前缀;
3.新建自动装配类,使用@Configuration和@Bean来进行自动装配;
4.新建spring.factories文件,指定Starter的自动装配类;

三.Starter的开发示例

下面,我就以创建一个自动配置并连接ElasticSearch的Starter来讲一下各个步骤及细节。 1.新建Maven项目,在项目的POM文件中定义使用的依赖。

<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.0.4.RELEASE</version></parent><modelVersion>4.0.0</modelVersion><artifactId>es-starter</artifactId><version>1.0.0.SNAPSHORT</version><dependencies><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.16.18</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId><version>2.0.4.RELEASE</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-configuration-processor</artifactId><optional>true</optional></dependency><dependency><groupId>org.elasticsearch.client</groupId><artifactId>x-pack-transport</artifactId><version>5.6.4</version></dependency></dependencies></project>

由于本starter主要是与ElasticSearch建立连接,获得TransportClient对象,所以需要依赖x-pack-transport包。

2.新建配置类,写好配置项和默认的配置值,指明配置项前缀。

package cn.sxw.commons.data.es.starter;import org.springframework.boot.context.properties.ConfigurationProperties;import lombok.Data;/*** Created by William on 2018/8/7.*/
@Data
@ConfigurationProperties(prefix = "sxw.elasticsearch")
public class ElasticSearchProperties {private String clusterName = "elasticsearch";private String clusterNodes = "127.0.0.1:9300";private String userName = "elastic";private String password = "changeme";}

指定配置项前缀为sxw.elasticsearch,各配置项均有默认值,默认值可以通过模块使用者的配置文件进行覆盖。

3.新建自动装配类,使用@Configuration@Bean来进行自动装配。

package cn.sxw.commons.data.es.starter;import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.transport.InetSocketTransportAddress;
import org.elasticsearch.common.transport.TransportAddress;
import org.elasticsearch.xpack.client.PreBuiltXPackTransportClient;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Arrays;
import java.util.stream.Collectors;import javax.annotation.Resource;import lombok.extern.slf4j.Slf4j;/*** Created by William on 2018/8/7.*/
@Slf4j
@Configuration
@EnableConfigurationProperties(ElasticSearchProperties.class)
public class ElasticSearchAutoConfiguration implements DisposableBean{private TransportClient transportClient;@Resourceprivate ElasticSearchProperties properties;@Bean@ConditionalOnMissingBean(TransportClient.class)public TransportClient transportClient() {log.debug("=======" + properties.getClusterName());log.debug("=======" + properties.getClusterNodes());log.debug("=======" + properties.getUserName());log.debug("=======" + properties.getPassword());log.info("开始建立es连接");transportClient = new PreBuiltXPackTransportClient(settings());TransportAddress[] transportAddresses= Arrays.stream(properties.getClusterNodes().split(",")).map (t->{String[] addressPortPairs = t.split(":");String address = addressPortPairs[0];Integer port = Integer.valueOf(addressPortPairs[1]);try {return new InetSocketTransportAddress(InetAddress.getByName(address), port);} catch (UnknownHostException e) {log.error("连接ElasticSearch失败", e);throw new RuntimeException ("连接ElasticSearch失败",e);}}).collect (Collectors.toList ()).toArray (new TransportAddress[0]);transportClient.addTransportAddresses(transportAddresses);return transportClient;}private Settings settings() {return Settings.builder().put("cluster.name", properties.getClusterName()).put("xpack.security.user", properties.getUserName() +":" + properties.getPassword()).build();}@Overridepublic void destroy() throws Exception {log.info("开始销毁Es的连接");if (transportClient != null) {transportClient.close();}}
}

本类主要对TransportClient类进行自动配置; @ConditionalOnMissingBean 当Spring容器中没有TransportClient类的对象时,调用transportClient()创建对象; 关于更多Bean的条件装配用法请自行查阅Spring Boot相关文档;

4.新建spring.factories文件,指定Starter的自动装配类。

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\cn.sxw.commons.data.es.starter.ElasticSearchAutoConfiguration

spring.factories文件位于resources/META-INF目录下,需要手动创建;org.springframework.boot.autoconfigure.EnableAutoConfiguration后面的类名说明了自动装配类,如果有多个 ,则用逗号分开; 使用者应用(SpringBoot)在启动的时候,会通过org.springframework.core.io.support.SpringFactoriesLoader读取classpath下每个Starter的spring.factories文件,加载自动装配类进行Bean的自动装配;

至此,整个Starter开发完毕,Deploy到中央仓库或Install到本地仓库后即可使用。

四.Starter的使用

1.创建Maven项目,依赖刚才发布的es-starter包。

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><parent><artifactId>spring-boot-parent</artifactId><groupId>org.springframework.boot</groupId><version>2.0.4.RELEASE</version></parent><modelVersion>4.0.0</modelVersion><artifactId>es-example</artifactId><version>1.0.0-SNAPSHOT</version><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>es-starter</artifactId><version>1.0.0.SNAPSHORT</version></dependency></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><configuration><source>1.8</source><target>1.8</target></configuration></plugin></plugins></build>
</project>

只需依赖刚才开发的es-starter即可

2.编写应用程序启动类。

package cn.sxw.commons.data.es.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;/*** Created by William on 2018/8/7.*/
@SpringBootApplication
@ComponentScan("cn.sxw.commons.data.es.example")
public class ExampleApplication {public static void main(String[] args) {SpringApplication.run(ExampleApplication.class, args);}
}

3.编写查询ElasticSearch的使用类

package cn.sxw.commons.data.es.example;import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;import java.util.Map;import lombok.extern.slf4j.Slf4j;/*** Created by William on 2018/8/7.*/
@Slf4j
@Component
public class ExampleRunner implements ApplicationRunner {private static final String INDEX_NAME = "tb_question";@Autowiredprivate TransportClient transportClient;@Overridepublic void run(ApplicationArguments applicationArguments) throws Exception {SearchResponse response = transportClient.prepareSearch(INDEX_NAME).setTypes(INDEX_NAME).setQuery(QueryBuilders.matchAllQuery()).setFrom(0).setSize(5).execute().actionGet();SearchHits hits = response.getHits();log.info(String.format("=======总共找到%d条记录", hits.getTotalHits()));log.info("=======第一页数据:");for (SearchHit searchHit : hits) {Map<String, Object> source = searchHit.getSource();String question = source.get("question").toString();log.info(question);}}
}

通过实现ApplicationRunner或CommandLineRunner接口,可以实现应用程序启动完成后自动运行run方法,达到测试es-starter模块目的。 索引名称tb_question是公司测试环境ElasticSearch中的索引,已存在数据。

4.应用程序配置

sxw:elasticsearch:cluster-name: docker-clustercluster-nodes: 192.168.2.180:9300,192.168.2.181:9300user-name: elasticpassword: changeme

在application.yml文件中配置es-starter需要的配置信息,这里连接公司测试环境中的ElasticSearch。 这里配置的值可以覆盖es-starter中默认值,也就是之前ElasticSearchProperties文件中的默认值。

5.运行程序测试

/Library/Java/JavaVirtualMachines/jdk1.8.0_25.jdk/Contents/Home/bin/java "-javaagent:/Applications/开发/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=52434:/Applications/开发/IntelliJ IDEA.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath cn.sxw.commons.data.es.example.ExampleApplication
objc[2017]: Class JavaLaunchHelper is implemented in both /Library/Java/JavaVirtualMachines/jdk1.8.0_25.jdk/Contents/Home/bin/java (0x1022a24c0) and /Library/Java/JavaVirtualMachines/jdk1.8.0_25.jdk/Contents/Home/jre/lib/libinstrument.dylib (0x1023254e0). One of the two will be used. Which one is undefined..   ____          _            __ _ _/\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\\/  ___)| |_)| | | | | || (_| |  ) ) ) )'  |____| .__|_| |_|_| |_\__, | / / / /=========|_|==============|___/=/_/_/_/:: Spring Boot ::        (v2.0.4.RELEASE)2018-08-08 16:26:43.161  INFO 2017 --- [           main] c.s.c.d.es.example.ExampleApplication    : Starting ExampleApplication on William.local with PID 2017 (/Users/William/Git/sxw-java/es-spring-boot-starter/es-example/target/classes started by William in /Users/William/Git/sxw-java/es-spring-boot-starter)
2018-08-08 16:26:43.167  INFO 2017 --- [           main] c.s.c.d.es.example.ExampleApplication    : No active profile set, falling back to default profiles: default
2018-08-08 16:26:43.365  INFO 2017 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@635eaaf1: startup date [Wed Aug 08 16:26:43 CST 2018]; root of context hierarchy
2018-08-08 16:26:45.078  INFO 2017 --- [           main] s.c.d.e.s.ElasticSearchAutoConfiguration : =======docker-cluster
2018-08-08 16:26:45.079  INFO 2017 --- [           main] s.c.d.e.s.ElasticSearchAutoConfiguration : =======192.168.2.180:9300,192.168.2.181:9300
2018-08-08 16:26:45.081  INFO 2017 --- [           main] s.c.d.e.s.ElasticSearchAutoConfiguration : =======elastic
2018-08-08 16:26:45.081  INFO 2017 --- [           main] s.c.d.e.s.ElasticSearchAutoConfiguration : =======changeme
2018-08-08 16:26:45.082  INFO 2017 --- [           main] s.c.d.e.s.ElasticSearchAutoConfiguration : 开始建立es连接
2018-08-08 16:26:46.200  INFO 2017 --- [           main] o.elasticsearch.plugins.PluginsService   : no modules loaded
2018-08-08 16:26:46.201  INFO 2017 --- [           main] o.elasticsearch.plugins.PluginsService   : loaded plugin [org.elasticsearch.index.reindex.ReindexPlugin]
2018-08-08 16:26:46.202  INFO 2017 --- [           main] o.elasticsearch.plugins.PluginsService   : loaded plugin [org.elasticsearch.join.ParentJoinPlugin]
2018-08-08 16:26:46.202  INFO 2017 --- [           main] o.elasticsearch.plugins.PluginsService   : loaded plugin [org.elasticsearch.percolator.PercolatorPlugin]
2018-08-08 16:26:46.202  INFO 2017 --- [           main] o.elasticsearch.plugins.PluginsService   : loaded plugin [org.elasticsearch.script.mustache.MustachePlugin]
2018-08-08 16:26:46.202  INFO 2017 --- [           main] o.elasticsearch.plugins.PluginsService   : loaded plugin [org.elasticsearch.transport.Netty3Plugin]
2018-08-08 16:26:46.202  INFO 2017 --- [           main] o.elasticsearch.plugins.PluginsService   : loaded plugin [org.elasticsearch.transport.Netty4Plugin]
2018-08-08 16:26:46.202  INFO 2017 --- [           main] o.elasticsearch.plugins.PluginsService   : loaded plugin [org.elasticsearch.xpack.XPackPlugin]
2018-08-08 16:26:49.137  INFO 2017 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-08-08 16:26:49.157  INFO 2017 --- [           main] c.s.c.d.es.example.ExampleApplication    : Started ExampleApplication in 6.6 seconds (JVM running for 7.915)
2018-08-08 16:26:49.215  INFO 2017 --- [           main] c.s.c.data.es.example.ExampleRunner      : =======总共找到907条记录
2018-08-08 16:26:49.215  INFO 2017 --- [           main] c.s.c.data.es.example.ExampleRunner      : =======第一页数据:
2018-08-08 16:26:49.230  INFO 2017 --- [           main] c.s.c.data.es.example.ExampleRunner      : <p>下列诗句朗读节奏有错误的一项是(  )</p>
2018-08-08 16:26:49.230  INFO 2017 --- [           main] c.s.c.data.es.example.ExampleRunner      : <p><span style=";font-family:宋体;color:rgb(0,0,0);font-size:14px"><span style="font-family:宋体">《卧薪尝胆》这个故事出自于(</span> A &nbsp;&nbsp;<span style="font-family:宋体">)</span></span></p><p><span style=";font-family:宋体;color:rgb(0,0,0);font-size:14px">A<span style="font-family:宋体">、司马迁《史记》 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="font-family:Times New Roman">B</span><span style="font-family:宋体">、司马光 《资治通鉴》</span></span></p><p><span style=";font-family:宋体;color:rgb(0,0,0);font-size:14px">C<span style="font-family:宋体">、孔子 &nbsp;&nbsp;《论语》 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="font-family:Times New Roman">D</span><span style="font-family:宋体">、司马迁《春秋》</span></span></p><p><br/></p>
2018-08-08 16:26:49.230  INFO 2017 --- [           main] c.s.c.data.es.example.ExampleRunner      : <p style="margin-bottom:7px;margin-bottom:auto;vertical-align:middle"><span style=";font-family:&#39;Cambria Math&#39;;font-size:14pxfont-family:宋体,新宋体">填空题</span></p><p style="margin-bottom:7px;margin-bottom:auto;vertical-align:middle"><span style=";font-family:&#39;Cambria Math&#39;;font-size:14pxfont-family:宋体,新宋体">该模式给当地带来的主要影响是 </span><span style=";font-family:&#39;Cambria Math&#39;;font-size:14px"><br/></span><br/></p><p><br/></p>
2018-08-08 16:26:49.231  INFO 2017 --- [           main] c.s.c.data.es.example.ExampleRunner      : <p>下列词语没有错别字的一项是(  )</p>
2018-08-08 16:26:49.231  INFO 2017 --- [           main] c.s.c.data.es.example.ExampleRunner      : <p>语文第16题</p>
2018-08-08 16:26:49.232  INFO 2017 --- [       Thread-2] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@635eaaf1: startup date [Wed Aug 08 16:26:43 CST 2018]; root of context hierarchy
2018-08-08 16:26:49.234  INFO 2017 --- [       Thread-2] o.s.j.e.a.AnnotationMBeanExporter        : Unregistering JMX-exposed beans on shutdown
2018-08-08 16:26:49.328  INFO 2017 --- [       Thread-2] s.c.d.e.s.ElasticSearchAutoConfiguration : 开始销毁Es的连接Process finished with exit code 0

运行程序,观察控制台输出,es-starter成功与ElasticSearch建立连接,且应用程序启动完后ExampleRunner的run方法查询出5条数据。