第六章：Java开发领域的知识图谱

import java.util.*;

// 实体类
class Entity {
    private String id;
    private String name;
    private String type;
    private Map<String, String> properties = new HashMap<>();
    
    public Entity(String id, String name, String type) {
        this.id = id;
        this.name = name;
        this.type = type;
    }
    
    // Getters, setters and other methods
}

// 关系类
class Relation {
    private String id;
    private Entity source;
    private Entity target;
    private String relationType;
    
    public Relation(String id, Entity source, Entity target, String relationType) {
        this.id = id;
        this.source = source;
        this.target = target;
        this.relationType = relationType;
    }
    
    // Getters, setters and other methods
}

// 知识图谱类
class KnowledgeGraph {
    private Map<String, Entity> entities = new HashMap<>();
    private Map<String, Relation> relations = new HashMap<>();
    
    // 添加实体
    public void addEntity(Entity entity) {
        entities.put(entity.getId(), entity);
    }
    
    // 添加关系
    public void addRelation(Relation relation) {
        relations.put(relation.getId(), relation);
    }
    
    // 查询与实体相关的所有关系
    public List<Relation> getRelatedRelations(String entityId) {
        List<Relation> result = new ArrayList<>();
        Entity entity = entities.get(entityId);
        if (entity != null) {
            for (Relation relation : relations.values()) {
                if (relation.getSource().equals(entity) || relation.getTarget().equals(entity)) {
                    result.add(relation);
                }
            }
        }
        return result;
    }
    
    // 查询特定类型的实体
    public List<Entity> getEntitiesByType(String type) {
        List<Entity> result = new ArrayList<>();
        for (Entity entity : entities.values()) {
            if (entity.getType().equals(type)) {
                result.add(entity);
            }
        }
        return result;
    }
    
    // 知识推理示例：找出所有子类
    public List<Entity> getAllSubclasses(String classEntityId) {
        List<Entity> result = new ArrayList<>();
        Queue<String> queue = new LinkedList<>();
        queue.offer(classEntityId);
        
        while (!queue.isEmpty()) {
            String currentId = queue.poll();
            for (Relation relation : relations.values()) {
                if (relation.getRelationType().equals("继承") && 
                    relation.getTarget().getId().equals(currentId)) {
                    Entity subclass = relation.getSource();
                    result.add(subclass);
                    queue.offer(subclass.getId());
                }
            }
        }
        return result;
    }
}

// 使用示例
public class JavaKnowledgeGraphExample {
    public static void main(String[] args) {
        // 创建知识图谱
        KnowledgeGraph javaKG = new KnowledgeGraph();
        
        // 创建实体
        Entity javaCore = new Entity("java001", "Java核心", "语言");
        Entity collection = new Entity("java002", "Java集合", "框架");
        Entity list = new Entity("java003", "List", "接口");
        Entity arrayList = new Entity("java004", "ArrayList", "类");
        Entity linkedList = new Entity("java005", "LinkedList", "类");
        
        // 添加实体到图谱
        javaKG.addEntity(javaCore);
        javaKG.addEntity(collection);
        javaKG.addEntity(list);
        javaKG.addEntity(arrayList);
        javaKG.addEntity(linkedList);
        
        // 创建关系
        Relation rel1 = new Relation("r001", collection, javaCore, "属于");
        Relation rel2 = new Relation("r002", list, collection, "属于");
        Relation rel3 = new Relation("r003", arrayList, list, "实现");
        Relation rel4 = new Relation("r004", linkedList, list, "实现");
        
        // 添加关系到图谱
        javaKG.addRelation(rel1);
        javaKG.addRelation(rel2);
        javaKG.addRelation(rel3);
        javaKG.addRelation(rel4);
        
        // 使用知识图谱进行查询
        System.out.println("List接口的所有实现类：");
        List<Relation> listImplementations = javaKG.getRelatedRelations("java003");
        for (Relation rel : listImplementations) {
            if (rel.getRelationType().equals("实现") && rel.getTarget().getId().equals("java003")) {
                System.out.println(" - " + rel.getSource().getName());
            }
        }
    }
}