Question

我有两个构建器类，分别返回Tree和Set。第二个构建器的执行只是第一个构建器的执行，具有额外的步骤和不同的返回类型。我真的不想在两个不同的类中复制相同的步骤，因为如果Tree - 构建过程发生了变化，我必须在两个类中更改代码。以下是两位建设者：

public class TreeBuilder {

    private NodeHelper nodeHelper;

    public TreeBuilder(NodeHelper nodeHelper) {
        this.nodeHelper = nodeHelper;
    }

    public Tree<EquipmentDetails> buildTree() {

        Tree<EquipmentDetails> tree = new Tree<>(nodeHelper.getEquipmentDetails(nodeHelper.getModelName()));

        return buildTree(tree);
    }

    private Tree<EquipmentDetails> buildTree(Tree<EquipmentDetails> parentTree) {

        Map<String, NativeSlotDisplayLabel> childSubTypeMap = nodeHelper.getChildSubTypeMap(parentTree);

        if (CommonUtils.nullOrEmpty(childSubTypeMap))
            return parentTree;

        for (String holderCommonName : childSubTypeMap.keySet()) {

            NativeSlotDisplayLabel nativeSlotDisplayLabel = childSubTypeMap.get(holderCommonName);

            EquipmentDetails equipmentDetails = nodeHelper.constructEqptDetails(holderCommonName, nativeSlotDisplayLabel, parentTree);

            Tree<EquipmentDetails> childTree = new Tree<>(equipmentDetails);

            parentTree.addChild(childTree);

            String equipmentCommonName = equipmentDetails.getModelEquipType();

            if (equipmentCommonName == null)
                continue;

            buildTree(childTree);
        }

        return parentTree;
    }
}

第二个构建器再使用一个依赖项并返回Set而不是Tree：

public class FreePortsBuilder {

    private NodeHelper nodeHelper;

    private PortLabelGenerator portLabelGenerator;

    public FreePortsBuilder(NodeHelper nodeHelper, PortLabelGenerator portLabelGenerator) {
        this.nodeHelper = nodeHelper;
        this.portLabelGenerator = portLabelGenerator;
    }

    public Set<PortNameAndLabel> collectFreePorts(){

        Tree<EquipmentDetails> tree = new Tree<>(nodeHelper.getEquipmentDetails(nodeHelper.getModelName()));

        Set<PortNameAndLabel> portNameAndLabels = new HashSet<>();

        return collectFreePorts(tree, portNameAndLabels);
    }

    private Set<PortNameAndLabel> collectFreePorts(Tree<EquipmentDetails> parentTree, Set<PortNameAndLabel> portNameAndLabels) {

        Map<String, NativeSlotDisplayLabel> childSubTypeMap = nodeHelper.getChildSubTypeMap(parentTree);

        if (CommonUtils.nullOrEmpty(childSubTypeMap))
            return portNameAndLabels;

        Set<PortNameAndLabel> generatedPortNameAndLabel = portLabelGenerator.getPortNameAndLabel(childSubTypeMap, parentTree.getUserObject());

        portNameAndLabels.addAll(generatedPortNameAndLabel);

        for (String holderCommonName : childSubTypeMap.keySet()) {

            NativeSlotDisplayLabel nativeSlotDisplayLabel = childSubTypeMap.get(holderCommonName);

            EquipmentDetails equipmentDetails = nodeHelper.constructEqptDetails(holderCommonName, nativeSlotDisplayLabel, parentTree);

            Tree<EquipmentDetails> childTree = new Tree<>(equipmentDetails);

            parentTree.addChild(childTree);

            String equipmentCommonName = equipmentDetails.getModelEquipType();

            if (equipmentCommonName == null)
                continue;

            collectFreePorts(childTree, portNameAndLabels);
        }

        return portNameAndLabels;
    }
}

我正在寻找避免重复的方法。有什么建议吗？

Answer 1

FreePortsBuilder同时做两件事：

构建Tree：如您所知，这与TreeBuilder的内容相同。
构建Set<PortNameAndLabel>，其中每个PortNameAndLabel似乎与最终Tree中的节点或子项（本身为Tree）相关联。

不是同时执行上述两项操作，而是按顺序执行。也就是说，在FreePortsBuilder，首先使用TreeBuilder来构建Tree，然后遍历此Tree来构建Set<PortNameAndLabel>。一种方法是执行此操作（我假设您的Tree类有一个方法，如getChildren()，返回List<Tree<EquipmentDetails>>）。

首先，允许客户通过添加getter获取TreeBuilder的{{1}}：

NodeHelper

然后，将public class TreeBuilder { private NodeHelper nodeHelper; public NodeHelper getNodeHelper() { return this.nodeHelper; } ... }而不是TreeBuilder注入NodeHelper（FreePortsBuilder，可以使用FreePortsBuilder中的NodeHelper，因为我们刚刚添加的吸气剂：

TreeBuilder

现在，public class FreePortsBuilder { private TreeBuilder treeBuilder; private PortLabelGenerator portLabelGenerator; public FreePortsBuilder(TreeBuilder treeBuilder, PortLabelGenerator portLabelGenerator) { this.treeBuilder = treeBuilder; this.portLabelGenerator = portLabelGenerator; } public Set<PortNameAndLabel> collectFreePorts() { Tree<EquipmentDetails> tree = treeBuilder.buildTree(); return collectFreePorts(tree); } private Set<PortNameAndLabel> collectFreePorts(Tree<EquipmentDetails> tree) { Set<PortNameAndLabel> portNameAndLabels = new HashSet<>(); for (Tree<EquipmentDetails> child : tree.getChildren()) { Map<String, NativeSlotDisplayLabel> childSubTypeMap = treeBuilder.getNodeHelper().getChildSubTypeMap(child); if (CommonUtils.nullOrEmpty(childSubTypeMap)) continue; Set<PortNameAndLabel> generatedPortNameAndLabel = portLabelGenerator.getPortNameAndLabel(childSubTypeMap, child.getUserObject()); portNameAndLabels.addAll(generatedPortNameAndLabel); } return portNameAndLabels; } }可以真正使用FreePortsBuilder实现，并删除代码重复。

Answer 2

您可以在此处使用Strategy design pattern或Template Method。你有一个算法，只有某些步骤改变（collectFreePorts＆amp; buildTree）。

如果您无法使用继承，则可以使用类似的解决方案：https://softwareengineering.stackexchange.com/questions/187872/template-method-within-one-class-without-subclasses-or-inheritance

避免具有不同返回类型的方法的代码重复

2 个答案: