SpringBoot项目创建参考【SpringBoot】SpringBoot快速入门(一)
本文介绍SpringBoot项目的POM文件、配置与单元测试
POM文件
1、SpringBoot的pom文件中,看到都依赖一个springboot的父项目,如下
1 <parent> 2 <groupId>org.springframework.boot</groupId> 3 <artifactId>spring‐boot‐starter‐parent</artifactId> 4 <version>2.1.8.RELEASE</version> 5 </parent>
而springboot的父项目又有一个父项目,此项目才是真正管理Spring Boot应用里面的所有依赖版本
1 <parent> 2 <groupId>org.springframework.boot</groupId> 3 <artifactId>spring-boot-dependencies</artifactId> 4 <version>2.1.8.RELEASE</version> 5 <relativePath>../../spring-boot-dependencies</relativePath> 6 </parent>
以后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)
依赖关系如下:
2、SpringBoot的启动器
spring-boot-starter: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
1 <dependencies> 2 <!-- 不需要写版本号,版本号依赖父项目(spring-boot-starter-parent)管理 --> 3 <!-- SpringBoot 将所有的功能场景抽取出来,做成一个个starter(启动器), 4 只需要在项目中引入这些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启动器--> 5 <dependency> 6 <groupId>org.springframework.boot</groupId> 7 <artifactId>spring-boot-starter-web</artifactId> 8 </dependency> 9 </dependencies>
主程序类,主入口类
1、主程序类,入口类
1 /** 2 * @SpringBootApplication 用来标注一个主程序,说明这是一个Spring Boot应用 3 */ 4 @SpringBootApplication 5 public class Application { 6 7 public static void main(String[] args) { 8 9 // Spring应用启动 10 SpringApplication.run(Application.class, args); 11 } 12 }
2、SpringBoot注解
a、@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;
1 @Target(ElementType.TYPE) 2 @Retention(RetentionPolicy.RUNTIME) 3 @Documented 4 @Inherited 5 @SpringBootConfiguration 6 @EnableAutoConfiguration 7 @ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class), 8 @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) }) 9 public @interface SpringBootApplication {
b、@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;
c、@SpringBootApplication > @SpringBootConfiguration > @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
d、@SpringBootApplication > @EnableAutoConfiguration: 开启自动配置功能; Spring配置的东西,SpringBoot开启自动配置功能;这样自动配置才能生效;
1 @Target(ElementType.TYPE) 2 @Retention(RetentionPolicy.RUNTIME) 3 @Documented 4 @Inherited 5 @AutoConfigurationPackage 6 @Import(AutoConfigurationImportSelector.class) 7 public @interface EnableAutoConfiguration {
e、@SpringBootApplication > @EnableAutoConfiguration > @AutoConfigurationPackage: 自动配置包
f、@SpringBootApplication > @EnableAutoConfiguration > @AutoConfigurationPackage > @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;
g、@SpringBootApplication > @EnableAutoConfiguration > @Import(EnableAutoConfigurationImportSelector.class); 选择要导入容器的组件,
EnableAutoConfigurationImportSelector: 导入哪些组件的选择器; 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;
有了自动配置类,免去了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
J2EE的整体整合解决方案和自动配置都在spring-boot-autoconfigure-2.1.8.RELEASE.jar;
SpringBoot自动配置原理
1、SpringBoot启动的时候加载主配置类,在主配置类@SpringBootApplication注解中,
开启了自动配置功能 @EnableAutoConfiguration
2、@EnableAutoConfiguration的作用
a、利用EnableAutoConfigurationImportSelector给容器中导入一些组件
b、EnableAutoConfigurationImportSelector类中,可以查看getAutoConfigurationEntry()方法的内容,代码逻辑如下
1 // 获取候选的配置 2 List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes); 3 4 5 // getCandidateConfigurations此方法中调用了 6 SpringFactoriesLoader.loadFactoryNames(getSpringFactoriesLoaderFactoryClass(), 7 getBeanClassLoader()); 8 9 // loadFactoryNames方法就会返回所有配置类名称 10 // 扫描所有jar包类路径下 META‐INF/spring.factories 11 // 把扫描到的这些文件的内容包装成properties对象 12 // 从properties中获取到EnableAutoConfiguration.class类(类名)对应的值,然后把他们添加在容器中
c、将 类路径下 META-INF/spring.factories 里面配置的所有EnableAutoConfiguration的值加入到了容器中; spring.factories内容如下:
1 # Auto Configure 2 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ 3 org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\ 4 org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\ 5 org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration,\ 6 org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration,\ 7 org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration,\ 8 org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration,\ 9 org.springframework.boot.autoconfigure.cloud.CloudServiceConnectorsAutoConfiguration,\ 10 org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration,\ 11 org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\ 12 org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration,\ 13 org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration,\ 14 org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,\ 15 org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration,\ 16 org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration,\ 17 org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveRepositoriesAutoConfiguration,\ 18 org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration,\ 19 org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration,\ 20 org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveDataAutoConfiguration,\ 21 org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveRepositoriesAutoConfiguration,\ 22 org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration,\ 23 org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchAutoConfiguration,\ 24 org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration,\ 25 org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\ 26 org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration,\ 27 org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\ 28 org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration,\ 29 org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration,\ 30 org.springframework.boot.autoconfigure.data.mongo.MongoReactiveDataAutoConfiguration,\ 31 org.springframework.boot.autoconfigure.data.mongo.MongoReactiveRepositoriesAutoConfiguration,\ 32 org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\ 33 org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration,\ 34 org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\ 35 org.springframework.boot.autoconfigure.data.solr.SolrRepositoriesAutoConfiguration,\ 36 org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\ 37 org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration,\ 38 org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration,\ 39 org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration,\ 40 org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,\ 41 org.springframework.boot.autoconfigure.elasticsearch.jest.JestAutoConfiguration,\ 42 org.springframework.boot.autoconfigure.elasticsearch.rest.RestClientAutoConfiguration,\ 43 org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\ 44 org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\ 45 org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\ 46 org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration,\ 47 org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\ 48 org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration,\ 49 org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration,\ 50 org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\ 51 org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\ 52 org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration,\ 53 org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration,\ 54 org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration,\ 55 org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\ 56 org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\ 57 org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\ 58 org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration,\ 59 org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration,\ 60 org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\ 61 org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration,\ 62 org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration,\ 63 org.springframework.boot.autoconfigure.jms.JndiConnectionFactoryAutoConfiguration,\ 64 org.springframework.boot.autoconfigure.jms.activemq.ActiveMQAutoConfiguration,\ 65 org.springframework.boot.autoconfigure.jms.artemis.ArtemisAutoConfiguration,\ 66 org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\ 67 org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration,\ 68 org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\ 69 org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\ 70 org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\ 71 org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration,\ 72 org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration,\ 73 org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\ 74 org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration,\ 75 org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration,\ 76 org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration,\ 77 org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\ 78 org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration,\ 79 org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\ 80 org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\ 81 org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration,\ 82 org.springframework.boot.autoconfigure.reactor.core.ReactorCoreAutoConfiguration,\ 83 org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration,\ 84 org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration,\ 85 org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration,\ 86 org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration,\ 87 org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration,\ 88 org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\ 89 org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\ 90 org.springframework.boot.autoconfigure.security.oauth2.client.servlet.OAuth2ClientAutoConfiguration,\ 91 org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration,\ 92 org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration,\ 93 org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration,\ 94 org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\ 95 org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration,\ 96 org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration,\ 97 org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\ 98 org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration,\ 99 org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration,\ 100 org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\ 101 org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration,\ 102 org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration,\ 103 org.springframework.boot.autoconfigure.web.reactive.HttpHandlerAutoConfiguration,\ 104 org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration,\ 105 org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\ 106 org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration,\ 107 org.springframework.boot.autoconfigure.web.reactive.function.client.ClientHttpConnectorAutoConfiguration,\ 108 org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration,\ 109 org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\ 110 org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\ 111 org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration,\ 112 org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration,\ 113 org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration,\ 114 org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\ 115 org.springframework.boot.autoconfigure.websocket.reactive.WebSocketReactiveAutoConfiguration,\ 116 org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration,\ 117 org.springframework.boot.autoconfigure.websocket.servlet.WebSocketMessagingAutoConfiguration,\ 118 org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration,\ 119 org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration
3、每一个自动配置类进行自动配置功能,每一个这样的 xxxAutoConfiguration类都是容器中的一个组件,都加入到容器中; 用他们来做自动配置;
4、以HttpEncodingAutoConfiguration(Http编码自动配置)为例解释自动配置原理;
1 @Configuration //表示这是一个配置类,以前编写的配置文件一样,也可以给容器中添加组件 2 @EnableConfigurationProperties(HttpEncodingProperties.class) //启动指定类的 3 ConfigurationProperties功能;将配置文件中对应的值和HttpEncodingProperties绑定起来;并把 4 HttpEncodingProperties加入到ioc容器中 5 6 7 //表示这是一个配置类,以前编写的配置文件一样,也可以给容器中添加组件 8 @Configuration 9 //启动指定属性类的,相当于将HttpProperties注入容器 10 @EnableConfigurationProperties(HttpProperties.class) 11 12 // Spring底层@Conditional注解,根据不同的条件,如果 满足指定的条件,整个配置类里面的配置就会生效; 13 // 判断当前应用是否是web应用,如果是,当前配置类生效 14 @ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.SERVLET) 15 16 // 判断当前项目有没有这个类 17 // CharacterEncodingFilter; SpringMVC中进行乱码解决的过滤器; 18 @ConditionalOnClass(CharacterEncodingFilter.class) 19 20 // 判断配置文件中是否存在某个配置 spring.http.encoding.enabled;如果不存在,判断也是成立的 21 // 即使配置文件中不配置pring.http.encoding.enabled=true,也是默认生效的; 22 @ConditionalOnProperty(prefix = "spring.http.encoding", value = "enabled", matchIfMissing = true) 23 public class HttpEncodingAutoConfiguration { 24 25 // 类已经和SpringBoot的配置文件映射了 26 private final HttpProperties.Encoding properties; 27 28 // 只有一个有参构造器的情况下,参数的值就会从容器中拿 29 public HttpEncodingAutoConfiguration(HttpProperties properties) { 30 this.properties = properties.getEncoding(); 31 } 32 33 // 给容器中添加一个组件,这个组件的某些值需要从properties中获取 34 @Bean 35 //判断容器没有这个组件? 没有则注入 36 @ConditionalOnMissingBean 37 public CharacterEncodingFilter characterEncodingFilter() { 38 CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter(); 39 filter.setEncoding(this.properties.getCharset().name()); 40 filter.setForceRequestEncoding(this.properties.shouldForce(Type.REQUEST)); 41 filter.setForceResponseEncoding(this.properties.shouldForce(Type.RESPONSE)); 42 return filter; 43 } 44 45 @Bean 46 public LocaleCharsetMappingsCustomizer localeCharsetMappingsCustomizer() { 47 return new LocaleCharsetMappingsCustomizer(this.properties); 48 } 49 50 private static class LocaleCharsetMappingsCustomizer 51 implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory>, Ordered { 52 53 private final HttpProperties.Encoding properties; 54 55 LocaleCharsetMappingsCustomizer(HttpProperties.Encoding properties) { 56 this.properties = properties; 57 } 58 59 @Override 60 public void customize(ConfigurableServletWebServerFactory factory) { 61 if (this.properties.getMapping() != null) { 62 factory.setLocaleCharsetMappings(this.properties.getMapping()); 63 } 64 } 65 66 @Override 67 public int getOrder() { 68 return 0; 69 } 70 71 } 72 73 }
根据当前不同的条件判断,决定这个配置类是否生效?
一但这个配置类生效;这个配置类就会给容器中添加各种组件;这些组件的属性是从对应的properties类中获取 的,这些类里面的每一个属性又是和配置文件绑定的;
5、所有在配置文件中能配置的属性都是在xxxxProperties类中封装着;配置文件能配置什么就可以参照某个功 能对应的这个属性类
1 // 从配置文件中获取指定的值和bean的属 性进行绑定 2 @ConfigurationProperties(prefix = "spring.http") 3 public class HttpProperties {
6、在配置文件中设置 debug = true,可以在控制台查看springboot自动配置的服务,启动了那些自动配置类。
精髓
1)、SpringBoot启动会加载大量的自动配置类
2)、使用时,查看需要的功能有没有SpringBoot默认写好的自动配置类;
3)、再来看这个自动配置类中到底配置了哪些组件; (只要我们要用的组件有,我们就不需要再来配置了)
4)、给容器中自动配置类添加组件的时候,会从properties类中获取某些属性。我们就可以在配置文件中指定这些属性的值;
xxxxAutoConfigurartion:自动配置类; 给容器中添加组件
SpringBoot单元测试
1、引入SpringBoot测试依赖
1 <dependency> 2 <groupId>org.springframework.boot</groupId> 3 <artifactId>spring-boot-starter-test</artifactId> 4 <scope>test</scope> 5 </dependency>
2、编辑测试类。TestSpringbootApplicationTests.java
1 package com.test.springboot; 2 3 import org.junit.Test; 4 import org.junit.runner.RunWith; 5 import org.springframework.beans.factory.annotation.Autowired; 6 import org.springframework.boot.test.context.SpringBootTest; 7 import org.springframework.context.ApplicationContext; 8 import org.springframework.test.context.junit4.SpringRunner; 9 10 /** 11 * SpringBoot单元测试 12 * 13 * 可以在测试期间很方便的类似编码一样的自动注入 14 */ 15 @RunWith(SpringRunner.class) 16 @SpringBootTest 17 public class TestSpringbootApplicationTests { 18 19 @Autowired 20 ApplicationContext context; 21 22 @Test 23 public void contextLoads(){ 24 boolean b = context.containsBean("helloController"); 25 System.out.println(b); 26 } 27 28 29 }
3、运行测试类测试方法,运行结果如下: