官方文档：https://spring.io/projects/spring-boot
底层注解
1、@Configuration
表示这是一个配置类
springboot的bean默认是单例的还是多例的？
@Configuration
public class MyConfig {
@Bean
public User user() {
return new User("张三", 4);
}
@Bean
public Pet pet() {
return new Pet("小强");
}
}
测试一下：
Object user01 = run.getBean("user");
Object user02 = run.getBean("user");
System.out.println(user01 == user02);
//输入：true
proxyBeanMethods：该参数是用来代理bean的
首先引出两个概念：Full 全模式，Lite 轻量级模式
Full(proxyBeanMethods = true) :proxyBeanMethods参数设置为true时即为：Full 全模式。 该模式下注入容器中的同一个组件无论被取出多少次都是同一个bean实例，即单实例对象，在该模式下SpringBoot每次启动都会判断检查容器中是否存在该组件
Lite(proxyBeanMethods = false) :proxyBeanMethods参数设置为false时即为：Lite 轻量级模式。该模式下注入容器中的同一个组件无论被取出多少次都是不同的bean实例，即多实例对象，在该模式下SpringBoot每次启动会跳过检查容器中是否存在该组件
测试一下
//proxyBeanMethods=true
MyConfig myConfig = run.getBean(MyConfig.class);
System.out.println(myConfig);//输出：com.link.boot.config.MyConfig$EnhancerBySpringCGLIB$5a8a306@143d9a93
User user01 = myConfig.user();
User user02 = myConfig.user();
System.out.println(user01 == user02);//输出：true
//proxyBeanMethods=false
MyConfig myConfig = run.getBean(MyConfig.class);//输出：com.link.boot.config.MyConfig@6e28bb87
System.out.println(myConfig);
User user01 = myConfig.user();
User user02 = myConfig.user();
System.out.println(user01 == user02);//输出：false
什么时候用Full全模式，什么时候用Lite轻量级模式？
2、@Bean、@Component、@Controller、@Service
3、@ConfigurationProperties
@Data
@ToString
@ConfigurationProperties(prefix = "person")
@Component
public class Person {
private String name;
private Integer age;
}
4、@EnableConfigurationProperties
@Data
@ConfigurationProperties(prefix = "car")
public class Car {
private String brand;
private int price;
}
@Configuration
@EnableConfigurationProperties(Car.class)
public class MyConfig {
}
5、@PropertiesSource与@ImportSource
/**
* 将配置文件中没一个属性的值都映射都这个实体中
*
* @ConfigurationProperties(prefix = "person")告诉SpringBoot把本类中的属性和配置文件中的属性进行绑定
*
* @PropertySource：加载指定的配置文件
*/
@PropertySource(value = "classpath:person.properties")
@Data
@ToString
@ConfigurationProperties(prefix = "person")
@Component
public class Person {
private String name;
private Integer age;
}
/**
* @SpringBootApplication 标注这是一个SpringBoot应用
*
* @ImportResource 注入spring的配置文件
*/
@SpringBootApplication
@ImportResource(locations = {"classpath:beans.xml"})
public class SpringBootDemo1Application {
public static void main(String[] args) {
SpringApplication.run(SpringBootDemo1Application.class, args);
}
}
6、@Import
三种用法：
直接填class数组方式
@Configuration
@Import({User.class, Car.class})
public class MyConfig {
}
ImportSelector方式【重点】
//这种方式的前提就是一个类要实现ImportSelector接口
public class MyTest implements ImportSelector {
@Override
public String[] selectImports(AnnotationMetadata importingClassMetadata) {
return new String[]{"com.link.boot.bean.Car"};
}
}
@Configuration
@Import(MyTest.class)
public class MyConfig {
}
ImportBeanDefinitionRegistrar方式
public class MyTest2 implements ImportBeanDefinitionRegistrar {
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(Car.class);
registry.registerBeanDefinition("car123", rootBeanDefinition);
}
}
7、@Conditional注解
| @Conditional拓展注解 | 作用（判断是否满足当前指定条件） |
|---|---|
| @ConditionalOnJava | 系统的java版本是否符合要求 |
| @ConditionalOnBean | 容器中存在指定Bean |
| @ConditionalOnMissingBean | 容器中不存在指定的Bean |
| @ConditionalOnExpression | 满足指定的SpEl表达式 |
| @ConditionalOnClass | 系统中有指定的类 |
| @ConditionalOnMissingClass | 系统中没有指定的类 |
| @ConditionalOnSingleCandidate | 容器中只有一个指定的Bean，或者这个Bean是首选Bean |
| @ConditionalOnProperty | 系统中指定的属性是否有指定的值 |
| @ConditionalOnResource | 类路径下是否存在指定的资源文件 |
| @ConditionalOnWebApplication | 当前是Web环境 |
| @ConditionalOnNotWebApplication | 当前不是Web环境 |
| @ConditionalOnJndi | JNDI存在指定项 |
自动配置原理：
引导加载自动配置类
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {
...
1、@SpringBootConfiguration
2、@ComponentScan
3、@EnableAutoConfiguration
@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {
@AutoConfigurationPackage
@Import(AutoConfigurationPackages.Registrar.class)
public @interface AutoConfigurationPackage {
//利用Registrar给容器导入一些列的组件
//将指定包下的所有组件导进来
@Import
@Import(AutoConfigurationImportSelector.class)
* SpringFactoriesLoader.loadFactoryNames()
扫描所有jar包的类路径下的 META-INF/spring.factories
把扫描到的这些文件的内容包装成properties对象
从properties中获取到EnableAutoConfiguration.class类对应的值，然后把他们添加到容器中
# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\
org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration,\
org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration,\
org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration,\
org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration,\
org.springframework.boot.autoconfigure.cloud.CloudServiceConnectorsAutoConfiguration,\
org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration,\
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration,\
org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration,\
org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.solr.SolrRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,\
org.springframework.boot.autoconfigure.elasticsearch.jest.JestAutoConfiguration,\
org.springframework.boot.autoconfigure.elasticsearch.rest.RestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration,\
org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration,\
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration,\
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration,\
org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration,\
org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JndiConnectionFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.activemq.ActiveMQAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.artemis.ArtemisAutoConfiguration,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration,\
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\
org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration,\
org.springframework.boot.autoconfigure.reactor.core.ReactorCoreAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityRequestMatcherProviderAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.servlet.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration,\
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\
org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.HttpHandlerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.ClientHttpConnectorAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.reactive.WebSocketReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration
@Configuration //表示这是一个配置类，跟以前在配置文件里面配置一样，也可以给容器中添加组件
@EnableConfigurationProperties(HttpProperties.class) //开启指定类的ConfigurationProperties功能；将配置文件配置对应的值和HttpProperties绑定起来
@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.SERVLET) //判断当前应用是否是基于servlet的web应用，如果是，则当前配置生效
@ConditionalOnClass(CharacterEncodingFilter.class) //判断当前项目是否存在这个类
@ConditionalOnProperty(prefix = "spring.http.encoding", value = "enabled", matchIfMissing = true) //判断配置文件中是否存在某个配置，matchIfMissing = true：如果不存在，spring.http.encoding.enabled=true 也是成立的
public class HttpEncodingAutoConfiguration {
private final HttpProperties.Encoding properties;
public HttpEncodingAutoConfiguration(HttpProperties properties) {
this.properties = properties.getEncoding();
}
@Bean //向容器中添加一个组件
@ConditionalOnMissingBean
public CharacterEncodingFilter characterEncodingFilter() {
CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
filter.setEncoding(this.properties.getCharset().name());
filter.setForceRequestEncoding(this.properties.shouldForce(Type.REQUEST));
filter.setForceResponseEncoding(this.properties.shouldForce(Type.RESPONSE));
return filter;
}
@ConfigurationProperties(prefix = "spring.http")//从配置文件中获取指定的值和Bean的属性进行绑定
public class HttpProperties {
private boolean logRequestDetails;
private final Encoding encoding = new Encoding();
============================
CONDITIONS EVALUATION REPORT
============================
Positive matches:(启用的自动配置类)
-----------------
CodecsAutoConfiguration matched:
- @ConditionalOnClass found required class 'org.springframework.http.codec.CodecConfigurer' (OnClassCondition)
CodecsAutoConfiguration.JacksonCodecConfiguration matched:
- @ConditionalOnClass found required class 'com.fasterxml.jackson.databind.ObjectMapper' (OnClassCondition)
Negative matches:(没有启用的自动配置类)
-----------------
ActiveMQAutoConfiguration:
Did not match:
- @ConditionalOnClass did not find required class 'javax.jms.ConnectionFactory' (OnClassCondition)
AopAutoConfiguration:
Did not match:
- @ConditionalOnClass did not find required class 'org.aspectj.lang.annotation.Aspect' (OnClassCondition)
总结：
- springboot先加载所有的自动配置类；
- 每个自动配置类按条件进行生效；
- 生效的配置类就会给容器中装配很多组件；
- 只要容器中有这些组件，功能就有了；
- 只有用户有自己的配置，就以用户的优先；
