1.以Hello类为例改为用注解方式

• Hello类，采用@Component注解：

  import org.springframework.stereotype.Component;
  
  /**
   * Created by Administrator on 2019/2/28.
    * @Component用于类级别注解，标注本类为一个可被Spring容器托管的
          */
      @Component
        public class Hello {
           public String gethello(){
              return "Hello World";
   }
  }
  

• HelloApp类，则采用@ComponentScan来注解：

  import org.springframework.context.ApplicationContext;
  import org.springframework.context.annotation.ComponentScan;
  import org.springframework.stereotype.Component;
  import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  
  /**
   * Created by Administrator on 2019/2/28.
   * @Component
   */
  
  @Component
  public class HelloApp {
      public static void main(String[] args) {
          //1.通过注解创建上下文对象
          ApplicationContext context = new AnnotationConfigApplicationContext(HelloApp.class);
          //2.读取bean
          Hello hello = context.getBean(Hello.class);
          //3.运行
          System.out.println(hello.gethello());
      }
  }
  

• 运行结果为：

  
  
  运行结果

2.以Student和Phone为例

• 首先学会如何使用Lombok插件

• 按照下面步骤安装并记得需要重启IDEA

  
  
  File-Settings...

找到Plugins

• 接下来添加依赖：

  <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.16.18</version>
        <scope>provided</scope>
    </dependency>
  

• Phone类

  import lombok.Data;
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.stereotype.Component;
  
  /**
   * Created by Administrator on 2019/2/28.
   * 采用注解和Lombok开发的Phone类
   */
  @Component
  @Data
  public class Phone {
      @Value("华为")
      private String brand;
  
      @Value("1888.88")
      private double price;
  }
  

• Student类

  import lombok.Data;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.stereotype.Component;
  
  /**
   * Created by Administrator on 2019/2/28.
   */
  @Component
  @Data
  public class Student {
      @Value("Sunming")
      private String name;
  
      @Value("21")
      private int age;
  
      //注入@Autowired注入
      @Autowired
      private Phone phone;
  }
  

• StudentApp类：

  import org.springframework.context.ApplicationContext;
  import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  import org.springframework.context.annotation.ComponentScan;
  
  /**
   * Created by Administrator on 2019/2/28.
   */
  @ComponentScan
  public class StudentApp {
      public static void main(String[] args) {
          ApplicationContext context = new AnnotationConfigApplicationContext(StudentApp.class);
          Student student=context.getBean(Student.class);
          System.out.println(student);
      }
  }
  

• 运行结果：

  
  
  运行结果

也可以看一下Spring的@Bean注解使用，加深理解。
Spring的@Bean注解使用