spring学习4-spring管理对象之间的关联关系

MesasageService 类
    package hello;
     import org.springframework.stereotype.Component;
     //注解的加入
     @Component
     public class MesasageService {
         public MesasageService() {
             super();
             System.out.println("MessageService...");
         }
         /**
          * 执行打印功能
          * @return 返回要打印的字符串
          */
         public String getMessage(){
             return "Hello World";
         }
     }MessagePrinter类
    package hello;
     import org.springframework.beans.factory.annotation.Autowired;
     import org.springframework.stereotype.Component;
     //注解的加入
     @Component
     public class MessagePrinter {
         //无参构造方法的加入
         public MessagePrinter() {
             super();
             System.out.println("MessagePrinter...");
         }
         private MesasageService service;
         /*
         * 简历和MessageService的关系
         * */
         //设置service的值
         @Autowired
         //创建关联关系
         public void setService(MesasageService service){
             this.service =service;
         }
         public void printMessage(){
             System.out.println(this.service.getMessage());
         }
     }ApplicationSpring类
    package hello;
     import org.springframework.context.ApplicationContext;
     import org.springframework.context.annotation.AnnotationConfigApplicationContext;
     import org.springframework.context.annotation.ComponentScan;
     //加入扫描
     @ComponentScan
     public class ApplicationSpring {
         public static void main(String[] args){
             System.out.println("appliaction....");
             //初始化spring
             ApplicationContext context =new AnnotationConfigApplicationContext(ApplicationSpring.class);
             //获取messagePrinter对象
             MessagePrinter printer=context.getBean(MessagePrinter.class);
             //获取messafeService对象
             //MesasageService service=context.getBean(MesasageService.class);
             //System.out.println(printer);
            // System.out.println(service);
            // printer.setService(service);
             //打印消息
             printer.printMessage();
         }
     }运行结果
    appliaction....
     10月 27, 2019 6:45:12 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
     信息: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@3d012ddd: startup date [Sun Oct 27 18:45:12 CST 2019]; root of context hierarchy
     MessageService...
     MessagePrinter...
     Hello World