SpringBoot2.0之@Configuration注解

SpringBoot2.0之@Configuration注解

在讲解

@Configuration

我们有一个User的bean和一个Dog的bean

• 现在我们通过原始的spring的方式去管理这两个bean

1. 通过配置文件beans.xml配置user和dog的bean

   <?xml version="1.0" encoding="UTF-8"?>
   <beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
   
   <bean id="user01" class="com.dashi.bean.User">
   <property name="name" value="zhangsan"/>
   <property name="age" value="18"/>
   </bean>
   
   <bean id="dog01" class="com.dashi.bean.Pet">
   <property name="name" value="哈利"/>
   </bean>
   
   </beans>

2. 创建ApplicationContext获取user bean

   /**
   * spring方式通过getbean
   /*
   public static void main(String[] args) {
   ApplicationContext ac = new FileSystemXmlApplicationContext("classpath:beans.xml");
   User user01 = (User) ac.getBean("user01");
   }现在我们通过原始的spring的方式去管理这两个bean**

• 接下来我们通过spring boot的@Configuration注解来实现bean的管理

  创建配置类

  MyConfig

  （该名称可以自定义）,该类通过@Configuration注解

  通过

  @Configuration

  注解的类就相当于spring的beans.xml文件，通过@Bean注解的方法即为一个个的bean。bean中的属性即为spring中的property属性

  /**
  * 相当于spring中的bean.xml的<bean id="user01"></bean>
  */
  @Configuration
  public class Myconfig {
  
  //方法的名称就是spring bean中的bean id 该方法为”user01“,属性为property
  @Bean
  public User user01(){
  return new User("zhangsan",18);
  }
  
  //方法的名称就是spring bean中的bean id 该方法为”dogPet“ 属性为property
  @Bean
  public Pet dogPet(){
  return new Pet("tom");
  }
  }

  1. 得到user和Pet的实体类

     @SpringBootApplication
     public class MainApplication {
     public static void main(String[] args) {
     //SpringApplication.run(MainApplication.class);
     ConfigurableApplicationContext run = SpringApplication.run(MainApplication.class);
     //        String[] names = run.getBeanDefinitionNames();
     //        for(String name:names){
     //            System.out.println(name);
     //        }
     
     User user01 = run.getBean("user01", User.class);
     System.out.println(user01.getName());
     Pet dogPet = run.getBean("dogPet", Pet.class);
     System.out.println(dogPet.getName());
     
     }
     }

  2. 运行结果如下：

     .   ____          _            __ _ _
     /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
     ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
     \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
     '  |____| .__|_| |_|_| |_\__, | / / / /
     =========|_|==============|___/=/_/_/_/
     :: Spring Bo
     56c
     ot ::        (v2.0.6.RELEASE)
     
     2021-05-09 10:45:08.692  INFO 15880 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
     2021-05-09 10:45:08.692  INFO 15880 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
     2021-05-09 10:45:09.136  INFO 15880 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
     2021-05-09 10:45:09.758  INFO 15880 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8888 (http) with context path ''
     2021-05-09 10:45:09.786  INFO 15880 --- [           main] com.dashi.MainApplication                : Started MainApplication in 4.501 seconds (JVM running for 7.13)
     
     zhangsan
     tom

最后

通过以上说明@Configuration使用SpringBoot的方式去创建一个Bean，以代替传统通过xml的方式声明Bean，简便了beans.xml的配置，具有实际的试用意义

转载自 https://www.javaman.cn/sb2/springboot-configuration