[英]How can i load the strategy map using spring and annotations?
我正在使用spring實現策略模式,並加載正確的策略實現,請遵循以下示例:
public class ShippingServiceImpl implements ShippingService {
// Map of strategies
private Map<ShippingType,ShippingCostStrategy> shippingCostStrategies;
@Required
public void setShippingCostStrategies(Map<ShippingType,ShippingCostStrategy> strategies) {
this.shippingCostStrategies = strategies;
}
@Override
public BigDecimal calculateShippingCost(ShoppingCart cart) {
return shippingCostStrategies.get(cart.getShippingType()).shippingCost(cart);
}
// ...other business logic...
}
加載此策略圖的最佳方法是什么? 我想要一種加載地圖並傳遞給setShippingCostStrategies的特定方法? 我可以使用Spring注釋嗎? 因為在此示例中,作者使用配置進行此操作:
<bean id="shippingService" class="it.nicus.springstrategy.ShippingServiceImpl">
<property name="shippingCostStrategies">
<map>
<entry>
<key><util:constant static- field="it.nicus.springstrategy.ShippingType.NORMAL"/></key>
<bean class="it.nicus.springstrategy.PerItemCostStrategyImpl">
<property name="baseCost" value="5.00"/>
<property name="costPerItem" value="2.00"/>
</bean>
</entry>
<entry>
<key><util:constant static- field="it.nicus.springstrategy.ShippingType.PRIME"/></key>
<bean class="it.nicus.springstrategy.FixedCostStrategyImpl">
<property name="fixedCost" value="3.00" />
</bean>
</entry>
</map>
</property>
</bean>
您可以使用<util:map>
標記將map
注冊為bean,然后使用@Resource
批注自動裝配該地圖。
<util:map id="strategyMap">
<entry>
<key>
<util:constant static-field="it.nicus.springstrategy.ShippingType.NORMAL" />
</key>
<bean class="it.nicus.springstrategy.PerItemCostStrategyImpl">
<property name="baseCost" value="5.00" />
<property name="costPerItem" value="2.00" />
</bean>
</entry>
<entry>
<key>
<util:constant static-field="it.nicus.springstrategy.ShippingType.PRIME" />
</key>
<bean class="it.nicus.springstrategy.FixedCostStrategyImpl">
<property name="fixedCost" value="3.00" />
</bean>
</entry>
</util:map>
然后,在ShippingServiceImpl
類中,將其像這樣注入:
public class ShippingServiceImpl implements ShippingService {
// Map of strategies
@Resource(name="strategyMap")
private Map<ShippingType,ShippingCostStrategy> shippingCostStrategies;
}
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