Question

我有两个服务类别。 WarehouseManagementService提供了管理仓库和库存的方法。 SalesManagementService提供了管理客户及其订单的方法。

要创建订单，必须检查订单项目数量是否足够。为此，我将使用WarehouseManagementService中的availableStock（Product p）方法。但我不知道如何正确调用此方法。

我是否必须在SalesManagementService中创建WarehouseManagementService的实例？还是应该将WarehouseManagementServiceInterface添加到SalesManagementService构造函数（依赖注入）？

一个好的架构看起来如何实现这两个类的松散耦合？

先谢谢了。

public class WarehouseManagementService implements WarehouseManagementServiceInterface {

    private DatabaseReadWarehouseInterface dbRead;
    private DatabaseWriteWarehouseInterface dbWrite;

    public int availableStock(Product p) {
    // returns available quantity of product
    }

}

public class SalesManagementService implements SalesManagementServiceInterface {

    private DatabaseReadSalesInterface dbRead;
    private DatabaseWriteSalesInterface dbWrite;

    public void addOrder(Order o) {
    // creates order, if product quantity is sufficient
    }

}

Answer 1

您有正确的感觉：应该注入依赖项。只要记住Single Responsibility Principle：“一堂课只有一个改变的理由”。

通过在WarehouseManagementService中构建SalesManagementService，您将添加SalesManagementService发生变化的第二个原因：当WarehouseManagementService的构建方式发生变化时。

要解决此问题，您可以使用成熟的Dependency Injection框架，也可以直接在SalesManagementService中添加构造函数参数开始：

public class SalesManagementService implements SalesManagementServiceInterface {

    private DatabaseReadSalesInterface dbRead;
    private DatabaseWriteSalesInterface dbWrite;
    private WarehouseManagementServiceInterface warehouseManagementService;

    constructor(DatabaseReadSalesInterface dbRead,
                DatabaseWriteSalesInterface dbWrite,
                WarehouseManagementServiceInterface warehouseManagementService) {
        this.dbRead = dbRead;
        this.dbWrite = dbWrite;
        this.warehouseManagementService = warehouseManagementService;
    }

    public void addOrder(Order o) {
    // creates order, if product quantity is sufficient
    }

}

然后在您的main方法中，注意实例化WarehouseManagementService并将其传递给SalesManagementService。

作为旁注，您可能希望将SalesManagementService和WarehouseManagementService的结构移入工厂，这些工厂为您提供SalesManagementServiceInterface和WarehouseManagementServiceInterface而不是具体的类（ “程序要接口，而不是实现”。

从另一个服务类调用服务方法

1 个答案: