Spring boot下@Autowired 注入为 NULL的问题 或者 WebSocket功能下 @Autowired 注入为 NULL的问题

错误写法

@ClientEndpoint
@Component
public class WebSocket{
	private static Map<String, String> sysUserMap = new HashMap<String, String>();

    @Autowired
    private ISysUserService sysUserService;
    
    @OnOpen
    public void onOpen(Session session, @PathParam(value = "userId") String userId) {
        // 你的业务逻辑
         SysUser sysUser = sysUserService.getById(this.userId);  // 这里sysUserService 变成了null
    }
}

正确写法

@RestController
@Slf4j
@ServerEndpoint("/websocket/{userId}") //此注解相当于设置访问URL
public class WebSocket{
	private static Map<String, String> sysUserMap = new HashMap<String, String>();

    private ISysUserService sysUserService;
    
	@Autowired
	public void setRepository(ISysUserService sysUserService) {
	      WebSocket.sysUserService = sysUserService;
	}
    
    @OnOpen
    public void onOpen(Session session, @PathParam(value = "userId") String userId) {
        // 你的业务逻辑
         SysUser sysUser = sysUserService.getById(this.userId);  // 这里sysUserService 就正常了
    }
}

亲测有效 感觉写法有点诡异，希望有大佬可以帮忙指出。