翻看之前專案程式碼，發現一段這樣的注入，將抽象類PaymentPlugin所有的子類注入到集合中

    @Inject
    private List<PaymentPlugin> paymentPlugins = new ArrayList<>();
    @Inject
    private Map<String, PaymentPlugin> paymentPluginMap = new HashMap<>();

全域性搜尋之後並沒有發現關於這兩處的配置，這究竟是如何實現的？

後來在搜尋引擎和實踐的幫助下發現，spring可以將一個介面

//抽象父類
public abstract class PaymentPlugin {
}

//子類
@Component("weixinPublicPaymentPlugin")
public class WeixinPublicPaymentPlugin extends PaymentPlugin {
}

@Component("t")
public class T extends PaymentPlugin {
}

//介面
public interface PluginService {
}

//實現類
 

@Service
public class PluginServiceImpl implements PluginService {
}

測試程式碼如下

@Controller("testController")
public class Test {
    
    @Resource(name="weixinPublicPaymentPlugin")
    private PaymentPlugin paymentPlugin;
    @Inject
    private List<PaymentPlugin> paymentPlugins = new ArrayList<>();
    @Inject
 

    private Map<String, PaymentPlugin> paymentPluginMap = new HashMap<>();
    @Inject
    private List<PluginService> pluginServices = new ArrayList<>();
    @Inject
    private Map<String, PluginService> pluginServiceMap = new HashMap<>();
    
    @RequestMapping("/test")
    @ResponseBody
    public void test() {
        System.out.println("注入單例項:"+paymentPlugin);
        System.out.println("抽象集合list:"+paymentPlugins);
        System.out.println("抽象集合map:"+paymentPluginMap);
        System.out.println("介面集合list:"+pluginServices);
        System.out.println("介面集合map:"+pluginServiceMap);
    }
}

列印結果如下

注入單例項:com[email protected]e7fdf9a3
抽象集合list:[[email protected], com[email protected]e7fdf9a3]
抽象集合map:{[email protected], weixinPublicPaymentPlugin=com[email protected]e7fdf9a3}
介面集合list:[[email protected]]
介面集合map:{[email protected]055ec87}

我在上網查詢相關資料的時候發現，有的部落格說spring無法注入抽象類，實測上述配置下，spring可以對抽象類進行注入，多個實現類，用name指定需要注入的bean即可。