Java annotation injection problem

1. The
problem of injecting Service at the Controller layer:
There are two common ways to obtain a bean without obtaining a bean:
1. Inject through annotations
2. Configure
annotation injection through xml : scan the Controller layer, and then inject the Service object

   @Controller  //web层



   //@Autowired
    private RoleService roleService;// RoleService 必须先创建bean 然后在注入
 public void setRoleService(RoleService roleService) {
    
    
	  this.roleService = roleService;}

xml placement

   <bean id="roleController" class="com.itheima.controller.RoleController">  <!--不采用注解  必须有set方法无参构造 -->

       <property name="roleService" ref="roleService"></property>

    </bean>