Spring Boot自动配置
简而言之， Spring Boot的自动配置是一个运行时（更准确地说，是应用程序启动时）的过程，考虑了众多因素，才决定Spring配置应该用哪个，不该用哪个。举几个例子，下面这些情况都是Spring Boot的自动配置要考虑的。
①Spring的JdbcTemplate是不是在Classpath里？如果是，并且有DataSource的Bean，则自动配置一个JdbcTemplate的Bean。
②Thymeleaf是不是在Classpath里？如果是，则配置Thymeleaf的模板解析器、视图解析器以及模板引擎。
③Spring Security是不是在Classpath里？如果是，则进行一个非常基本的Web安全设置。每当应用程序启动的时候， Spring Boot的自动配置都要做将近200个这样的决定，涵盖安全、集成、持久化、 Web开发等诸多方面。所有这些自动配置就是为了尽量不让你自己写配置。有意思的是，自动配置的东西很难写在书本里。如果不能写出配置，那又该怎么描述并讨论它们呢？
在向应用程序加入Spring Boot时，有个名为spring-boot-autoconfigure的JAR文件，其中包含了很多配置类。每个配置类都在应用程序的Classpath里，都有机会为应用程序的配置添砖加瓦。这些配置类里有用于Thymeleaf的配置，有用于Spring Data JPA的配置，有用于Spiring MVC的配置，还有很多其他东西的配置，你可以自己选择是否在Spring应用程序里使用它们。所有这些配置如此与众不同，原因在于它们利用了Spring的条件化配置，这是Spring 4.0引入的新特性。条件化配置允许配置存在于应用程序中，但在满足某些特定条件之前都忽略这个配置。在Spring里可以很方便地编写你自己的条件，你所要做的就是实现Condition接口，覆盖它的matches()方法。举例来说，下面这个简单的条件类只有在Classpath里存在JdbcTemplate时才会生效
虽然本例中的条件相当简单，但Spring Boot定义了很多更有趣的条件，并把它们运用到了配置类上，这些配置类构成了Spring Boot的自动配置。 Spring Boot运用条件化配置的方法是，定义多个特殊的条件化注解，并将它们用到配置类上。表2-1列出了Spring Boot提供的条件化注解。
Spring Boot提供多少自动配置模块(org.springframework.boot.autoconfigure META-INF/spring.factories)
# Initializers
org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer,\
org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener
# Application Listeners
org.springframework.context.ApplicationListener=\
org.springframework.boot.autoconfigure.BackgroundPreinitializer
# Auto Configuration Import Listeners
org.springframework.boot.autoconfigure.AutoConfigurationImportListener=\
org.springframework.boot.autoconfigure.condition.ConditionEvaluationReportAutoConfigurationImportListener
# Auto Configuration Import Filters
org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
org.springframework.boot.autoconfigure.condition.OnClassCondition
# 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.CloudAutoConfiguration,\
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.jpa.JpaRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.ldap.LdapDataAutoConfiguration,\
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.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.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
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.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
# Failure analyzers
org.springframework.boot.diagnostics.FailureAnalyzer=\
org.springframework.boot.autoconfigure.diagnostics.analyzer.NoSuchBeanDefinitionFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.DataSourceBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.HikariDriverConfigurationFailureAnalyzer,\
org.springframework.boot.autoconfigure.session.NonUniqueSessionRepositoryFailureAnalyzer
# Template availability providers
org.springframework.boot.autoconfigure.template.TemplateAvailabilityProvider=\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.mustache.MustacheTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.web.servlet.JspTemplateAvailabilityProvider
Spring Boot封装好的Condition在这里(org.springframework.boot.autoconfigure.condition)
下面举个简单例子来说明
4.0.0
vip.fkandy
springboot
0.0.1-SNAPSHOT
jar
springboot
Demo project for Spring Boot
org.springframework.boot
spring-boot-starter-parent
2.0.5.RELEASE
UTF-8
UTF-8
1.8
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-test
test
org.springframework.boot
spring-boot-maven-plugin
package vip.fkandy.condition;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
public class GBKCondition implements Condition {
@Override
public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
String encoding = System.getProperty("file.encoding");
if (null != encoding) {
return "gbk".equals(encoding.toLowerCase());
}
return false;
}
}
package vip.fkandy.condition;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
public class UTF8Condition implements Condition {
@Override
public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
String encoding = System.getProperty("file.encoding");
if (null != encoding) {
return "utf-8".equals(encoding.toLowerCase());
}
return false;
}
}
package vip.fkandy.config;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import vip.fkandy.condition.GBKCondition;
import vip.fkandy.condition.UTF8Condition;
import vip.fkandy.convert.EncodingConvert;
import vip.fkandy.convert.GBKEncodingConvert;
import vip.fkandy.convert.UTF8EncodingConvert;
/**
* @Condition 基于条件的配置，一般配合Condition接口一起使用，
* 只有接口的实现类返回true才装配，否则不装配
* @author chenjianfei
*/
@SpringBootConfiguration
public class EncodingConvertConfig {
@Bean
@Conditional(GBKCondition.class)
public EncodingConvert createGBKEncodingConvert() {
return new GBKEncodingConvert();
}
@Bean
@Conditional(UTF8Condition.class)
public EncodingConvert createUTF8EncodingConvert() {
return new UTF8EncodingConvert();
}
}
package vip.fkandy.convert;
public interface EncodingConvert {
}
package vip.fkandy.convert;
public class GBKEncodingConvert implements EncodingConvert {
}
package vip.fkandy.convert;
public class UTF8EncodingConvert implements EncodingConvert{
}
package vip.fkandy;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import vip.fkandy.convert.EncodingConvert;
/**
* Condition实现接口boolean matches(ConditionContext context, AnnotatedTypeMetadata
* metadata);方法
*
* @Condition 基于条件的配置，一般配合Condition接口一起使用，
* 只有接口的实现类返回true才装配，否则不装配；这个注解可以使用在方法上也可以使用在类是哪个
*
*
*
* @author chenjianfei
*
*/
@SpringBootApplication
public class Application {
public static void main(String[] args) {
ConfigurableApplicationContext context = SpringApplication.run(Application.class, args);
System.out.println(context.getBeansOfType(EncodingConvert.class));
}
}
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.0.5.RELEASE)
2018-10-02 09:00:54.686 INFO 12696 --- [ main] vip.fkandy.Application : Starting Application on DESKTOP-6FVEB35 with PID 12696 (C:\eclipse-workspace\00\springboot-1\target\classes started by chenjianfei in C:\eclipse-workspace\00\springboot-1)
2018-10-02 09:00:54.689 INFO 12696 --- [ main] vip.fkandy.Application : No active profile set, falling back to default profiles: default
2018-10-02 09:00:54.730 INFO 12696 --- [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@5a955565: startup date [Tue Oct 02 09:00:54 CST 2018]; root of context hierarchy
2018-10-02 09:00:56.078 INFO 12696 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8181 (http)
2018-10-02 09:00:56.093 INFO 12696 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2018-10-02 09:00:56.094 INFO 12696 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.34
2018-10-02 09:00:56.097 INFO 12696 --- [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: [D:\jdk1.8.0_161\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;D:/jdk1.8.0_161/bin/../jre/bin/server;D:/jdk1.8.0_161/bin/../jre/bin;D:/jdk1.8.0_161/bin/../jre/lib/amd64;D:\app\chenjianfei\product\11.2.0\client_1\bin;C:\Program Files (x86)\Intel\iCLS Client\;C:\Program Files\Intel\iCLS Client\;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;D:\jdk1.8.0_161\bin;D:\apache-maven-3.5.2\bin;D:\Git\cmd;D:\gradle-4.5\bin;D:\scala-2.12.6\bin;D:\zookeeper-3.4.12\bin;D:\Program Files\TortoiseSVN\bin;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\;C:\WINDOWS\System32\OpenSSH\;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\;C:\Users\chenjianfei\AppData\Local\Microsoft\WindowsApps;C:\Users\chenjianfei\AppData\Local\GitHubDesktop\bin;D:\STS_4.0;;.]
2018-10-02 09:00:56.173 INFO 12696 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2018-10-02 09:00:56.173 INFO 12696 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1445 ms
2018-10-02 09:00:56.223 INFO 12696 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/]
2018-10-02 09:00:56.227 INFO 12696 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-10-02 09:00:56.228 INFO 12696 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-10-02 09:00:56.228 INFO 12696 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-10-02 09:00:56.228 INFO 12696 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2018-10-02 09:00:56.355 INFO 12696 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-10-02 09:00:56.571 INFO 12696 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@5a955565: startup date [Tue Oct 02 09:00:54 CST 2018]; root of context hierarchy
2018-10-02 09:00:56.629 INFO 12696 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-10-02 09:00:56.631 INFO 12696 --- [ 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)
2018-10-02 09:00:56.653 INFO 12696 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-10-02 09:00:56.653 INFO 12696 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-10-02 09:00:56.803 INFO 12696 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2018-10-02 09:00:56.850 INFO 12696 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8181 (http) with context path ''
2018-10-02 09:00:56.853 INFO 12696 --- [ main] vip.fkandy.Application : Started Application in 2.406 seconds (JVM running for 3.121)
{createUTF8EncodingConvert=vip.fkandy.convert.UTF8EncodingConvert@69adf72c}
再举个例子：使用Spring Boot提供的@ConditionalOnJava
package vip.fkandy.config;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnJava;
import org.springframework.boot.autoconfigure.condition.ConditionalOnJava.Range;
import org.springframework.boot.system.JavaVersion;
import org.springframework.context.annotation.Bean;
@SpringBootConfiguration
public class JDKVersionConfig {
@Bean
@ConditionalOnJava(range = Range.EQUAL_OR_NEWER, value = JavaVersion.EIGHT)
public Runnable createJDKVersion1() {
System.out.println("testJDKVersion1");
return () -> {
};
}
@ConditionalOnJava(range = Range.OLDER_THAN, value = JavaVersion.EIGHT)
public Runnable createJDKVersion2() {
System.out.println("testJDKVersion2");
return () -> {
};
}
}
以上这个例子会输出testJDKVersion1，因为当前编译环境的jdk版本为1.8
再举个例子：
①属性文件中server.port=8181的时候加载
②类路径下包含指定类才加载
③根据容器中是否存在某个Bean才加载
package vip.fkandy.config;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.annotation.Bean;
/**
* 两个小例子
*
* @author chenjianfei
*
*/
@SpringBootConfiguration
public class ConfigurationConfig {
/**
* 属性文件包含server.port=8181的时候加载bean
*
* @return
*/
@Bean
@ConditionalOnProperty(name = "server.port", havingValue = "8181")
public Runnable createRunnable() {
return () -> {
};
}
/**
* 类路径下(是否在pom中包含依赖)包含指定的类才加载
*
* @return
*/
@Bean
@ConditionalOnClass(name = "com.google.gson.Gson")
public Runnable createGsonRunnable() {
return () -> {
};
}
/**
* Spring容器中包含指定的Bean才加载(只有创建了User类，并使其加入到容器中)
*
* @return
*/
@Bean
@ConditionalOnBean(name = "user")
public Runnable createBeannRunnable() {
return () -> {
};
}
}
更多资料：
https://yq.aliyun.com/articles/66455
https://www.cnblogs.com/hafiz/p/9155017.html