1. HelloWorld的例子改成用注解来实现

• HelloWorld类，采用@Component注解

  package com.spring.annotation;
  import org.springframework.stereotype.Component;
  @Component
  public class HelloWorld {
     public String getHello() {
          return "Hello World";
     }
  }
  

• HelloWorldApp类，采用@ComponentScan注解

  package com.spring.annotation;
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  import org.springframework.context.annotation.ComponentScan;
  
  @ComponentScan
  public class HelloApp {
  
  public static void main(String[] args) {
    ApplicationContext context = new AnnotationConfigApplicationContext(HelloApp.class);
    HelloWorld  helloWorld = context.getBean(HelloWorld.class);
    System.out.println(helloWorld.getHello());
      }
  }
  

• 运行结果

  
  image.png

2、Student和Phone的例子改成用注解的方法实现

• Lombok插件的使用
  打开Settings,选择Plugins，搜索Lombok，安装，重启IDEA
  添加依赖

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

• Phone类

   package com.spring.annotation;
  import lombok.Data;
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.stereotype.Component;
  
  /**
  * 采用注解和Lombok开发的Phone类
  */
  @Component
  @Data
  public class Phone {
  @Value("iPhoneX")
  private String brand;
  
  @Value("6666.66")
  private double price;
  }
  

• Student类

  package com.spring.annotation;
  
  import lombok.Data;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.stereotype.Component;
  
  @Component
  @Data
  public class Student {
  @Value("Tom")
  private  String name;
  
  @Value("20")
  private int age;
  //使用@Autowired注入一个Phone类型的bean
  @Autowired
  private Phone phone;
  }
  

• StudentApp类

  package com.spring.annotation;
  
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  import org.springframework.context.annotation.ComponentScan;
  @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

  
  image.png

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