注解开发-定义bean

• 使用@Component定义bean

  // BookDaoImpl.java
  @Component("bookDao")
  public class BookDaoImpl implements BookDao {
      @Override
      public void save() {
          System.out.println("book dao save ...");
      }
  }
  
  // BookServiceImpl.java
  @Component
  public class BookServiceImpl implements BookService {
      @Override
      public void save() {
          System.out.println("book service save ...");
      }
  }
  

• 核心配置文件中通过组件扫描加载bean

  <?xml version="1.0" encoding="UTF-8"?>
  <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:context="http://www.springframework.org/schema/context"
      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
              http://www.springframework.org/schema/context
              http://www.springframework.org/schema/context/spring-context.xsd
          ">
      <context:component-scan base-package="com.charley"/>
  </beans>
  

• Spring提供@Component注解的三个衍生注解

  • @Controller：用于表现层bean定义

  • @Service：用于业务层bean定义

  • @Reposiitory：用于数据层bean定义

        // BookDaoImpl.java
        @Repository("bookDao")
        public class BookDaoImpl implements BookDao {
            @Override
            public void save() {
                System.out.println("book dao save ...");
            }
        }
    
        // BookServiceImpl.java
        @Service
        public class BookServiceImpl implements BookService {
            @Override
            public void save() {
                System.out.println("book service save ...");
            }
        }