我在实际开发中遇到有一段公共的代码，几个方法都需要掉，但如果单独拉出来写一个方法的话，入参又不同，所以想到了用泛型。

比如这是一段公共代码：

//保存订单信息,需要多个方法调用OrderFilterRequest orderFilterRequest = new OrderFilterRequest();btOrderFilterRequest.setUserId("1");btOrderFilterRequest.setStatus("0");List
     
       orderResultList = orderService.findOrders(orderFilterRequest);Order result = null;	if(CollectionUtils.isEmpty(orderResultList )){    Order order = CopierUtils.convert(request, Order.class);    order.setRealName(customer.getRealName());    order.setIdcardNo(customer.getIdcardNo());    order.setOrderNo("order" + DateUtil.getYMDHMS());    order.setStatus("0");    order.setCreateTime(new Date());    order.setUpdateTime(new Date());    order.setUserId("1");    result = orderService.createOrder(Order);}else{    Order orderResult =  orderResultList.get(0);    CopierUtils.copy(request, orderResult);    orderResult.setUpdateTime(new Date());    result = orderService.updateOrder(btOrderResult);}
     

将这段代码提炼成泛型类：

@Transactional(readOnly = true)@Componentpublic class OrderRequest
     
      {		@Autowired	private OrderService orderService;	@Transactional	public Order orderInfoSave(T request) {		OrderFilterRequest orderFilterRequest = new OrderFilterRequest();                btOrderFilterRequest.setUserId("1");                btOrderFilterRequest.setStatus("0");                List
      
        orderResultList = orderService.findOrders(orderFilterRequest);                Order result = null;	                if(CollectionUtils.isEmpty(orderResultList )){                    Order order = CopierUtils.convert(request, Order.class);                    order.setRealName(customer.getRealName());                    order.setIdcardNo(customer.getIdcardNo());                    order.setOrderNo("order" + DateUtil.getYMDHMS());                    order.setStatus("0");                    order.setCreateTime(new Date());                    order.setUpdateTime(new Date());                    order.setUserId("1");                    result = orderService.createOrder(Order);                }else{                    Order orderResult =  orderResultList.get(0);                    CopierUtils.copy(request, orderResult);                    orderResult.setUpdateTime(new Date());                    result = orderService.updateOrder(btOrderResult);                }        return result;	}}
      
     

最开始我是这么调用的：

public void method1(Request1 request ) {     OrderRequest
     
       orderCreateRequest = new OrderRequest
      
       ();     Order result = OrderCreateRequest.orderInfoSave(request);}public void method2(Request2 request ) {     OrderRequest
       
         orderCreateRequest = new OrderRequest
        
         ();     Order result = OrderCreateRequest.orderInfoSave(request);}
        
       
      
     

但是OrderRequest中orderService为null。（在controller层中注入service接口，在service层中注入orderService是有值的），尝试可很多解决办法，最后发现，原来spring自定义的类实例化时也需要用注入的方式，不能用new，否则脱离了spring的管理。改成如下方式就可以了：

@Autowiredprivate OrderRequest
     
       request1;@Autowiredprivate OrderRequest
      
        request2;public void method1(Request1 request ) {     Order result = request1.orderInfoSave(request);}public void method2(Request2 request ) {     Order result = request2.orderInfoSave(request);}