带有命令模式的springbeans映射

Question

我有不同实现的< code>ProductHandler类，例如< code>ABCProductHandler、< code>DEFProductHandler等..它们是使用如下所示的命令模式从< code>ProductServiceImpl类调用的。

产品ServiceImpl类：

@Service
public class ProductServiceImpl implements ProductService {

    private Map<ProductType,ProductHandler> productHandlersMap = 
                                         new EnumMap<>(ProductType.class);

    private ABCProductHandler abcProductHandler;

    private DEFProductHandler defProductHandler;

    //....10 other product handlers goes here

    @Autowired
    public ProductServiceImpl(ABCProductHandler abcProductHandler, 
                                  DEFProductHandler defProductHandler, .....) {
        this.abcProductHandler = abcProductHandler;
        this.defProductHandler = defProductHandler;
        //....10 other product handlers goes here
    }

    @PostConstruct() 
    public void init() {
        productHandlersMap.put(ProductType.ABC, abcProductHandler);
        productHandlersMap.put(ProductType.DEF, defProductHandler);
        //....10 other product handlers goes here
    }

    @Override
    public ProductDetails calculateProductPrice(ProductType productType) {
        productHandlersMap.get(productType).calculate();
        //..some otehr code goes here
        return productDetails;
    }
}

但是，我对上面的 ProductServiceImpl 类不满意，因为有很多带有样板代码的产品处理程序Map.put 调用。

现在，我的问题是，有什么方法可以轻松加载productHandlersMap？

@Service
public class ProductServiceImpl implements ProductService {

    private Map<ProductType,ProductHandler> productHandlersMap = 
                        new EnumMap<>(ProductType.class);

    @PostConstruct() 
    public void init() {
         //How to laod productHandlersMap easily with 
         // different ProductHandler types here?
    }

    @Override
    public ProductDetails calculateProductPrice(ProductType productType) {
        productHandlersMap.get(productType).calculate();
        //..some other code goes here
        return productDetails;
    }
}

Answer 1

您可以创建Spring配置组件

@Configuration
public class CollectionConfig {

    @Bean
    public ProductHandler  getABC() {
        return new ABCProductHandler(ProductType.ABC);
    }

    @Bean
    public ProductHandler  getDEF() {
        return new DEFProductHandler(ProductType.DEF);
    }

    @Bean
    public ProductHandler  getXYZ() {
        return new XYZProductHandler(ProductType.XYZ);

    }
 

    // other factory methods

}

之后：

    @Service 
public class ProductServiceImpl implements ProductService { 
private Map<ProductType,ProductHandler> productHandlersMap = new EnumMap<>(ProductType.class); 

 @Autowired(required = false)
 private List<ProductHandler> beanList;

 @PostConstruct() 
public void init() { 
    beanList.foreach(b->
    productHandlersMap.put(b.getType(), b))
     }
}

Answer 2

Spring可以将实现接口< code>I的bean的不同实现自动连接到< code>Map类型的属性

public enum ProductType {
    ABC(ProductType.ABC_BEAN_NAME),
    DEF(ProductType.DEF_BEAN_NAME);

    public static final String ABC_BEAN_NAME = "abcProductHandler";
    public static final String DEF_BEAN_NAME = "defProductHandler";

    private String beanName;

    ProductType(String beanName) { this.beanName = beanName; }

    public String beanName() { return beanName; }
}

然后，在@Configuration工厂类中或通过@Service或 annotation定义不同的

@Service(ProductType.ABC_BEAN_NAME)
public class ABCProductHandler implements ProductHandler {

    // ...
}

@Service(ProductType.DEF_BEAN_NAME)
public class DEFProductHandler implements ProductHandler {

    // ...
}

现在，在您的< code > ProductServiceImpl bean中，只需自动连接一个< code >映射

@Service
public class ProductServiceImpl implements ProductService {

    private final Map<String, ProductHandler> productHandlersMap;

    @Autowired
    public ProductServiceImpl(Map<String, ProductHandler> productHandlersMap) {
        this.productHandlersMap = productHandlersMap;
    }

    @Override
    public ProductDetails calculateProductPrice(ProductType productType) {
        productHandlersMap.get(productType.beanName()).calculate();
        //..some otehr code goes here
        return productDetails;
    }
}

这样，您可以让Spring完成所有的注入工作，甚至不需要使用< code>@PostConstruct方法。

请注意< code > calculate product price 方法中< code > product type . bean name()的使用。这确保您使用正确的bean来计算价格。