項目結構
PolicyController
package com.example.policyquerysystem.controller;

import com.example.policyquerysystem.dto.PolicyQueryDto;
import com.example.policyquerysystem.dto.PolicyTypeTreeDTO;
import com.example.policyquerysystem.dto.TypeNodeDTO;
import com.example.policyquerysystem.entity.Policy;
import com.example.policyquerysystem.entity.PolicyType;
import com.example.policyquerysystem.service.PolicyService;
import com.example.policyquerysystem.service.PolicyTypeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

@Controller
@RequestMapping("/policy")
public class PolicyController {

@Autowired
private PolicyService policyService;

@Autowired
private PolicyTypeService policyTypeService;

@GetMapping("/")
public String index(Model model) {
    // 獲取分類樹數據
    List<PolicyTypeTreeDTO> typeTree = policyTypeService.getFullTypeTree();
    model.addAttribute("typeTree", typeTree);

    // 添加空白查詢DTO
    model.addAttribute("queryDto", new PolicyQueryDto());

    return "index";
}


@GetMapping("/detail/{id}")
public String detail(@PathVariable Long id, Model model) {
    Policy policy = policyService.getPolicyById(id);
    if (policy != null) {
        String typeName = policyTypeService.getTypeNameById(policy.getType());
        model.addAttribute("policy", policy);
        model.addAttribute("typeName", typeName);
    }
    return "policy-detail";
}

@GetMapping("/search")
public String searchForm(Model model) {
    List<TypeNodeDTO> typeTree = policyTypeService.getTypeTreeAsDTO();
    model.addAttribute("typeTree", typeTree);
    model.addAttribute("queryDto", new PolicyQueryDto());
    return "search-form";
}

@PostMapping("/search")
public String search(PolicyQueryDto queryDto, Model model) {
    List<Policy> policies = policyService.advancedSearchWithSpecification(queryDto);
    String typeName = queryDto.getType() != null && !queryDto.getType().isEmpty()
            ? policyTypeService.getTypeNameById(queryDto.getType())
            : "";

    model.addAttribute("policies", policies);
    model.addAttribute("queryDto", queryDto);
    model.addAttribute("typeName", typeName);
    return "policy-list";
}

@GetMapping("/types")
public String showTypeTree(Model model) {
    model.addAttribute("typeTree", policyTypeService.getFullTypeTree());
    return "policy-type-tree";
}

@GetMapping("/type/{typeId}")
public String listByType(@PathVariable String typeId, Model model) {
    // 先獲取分類名稱
    String typeName = policyTypeService.getTypeNameById(typeId);

    // 使用分類名稱查詢政策
    List<Policy> policies = policyService.findByTypeName(typeName);

    model.addAttribute("policies", policies);
    model.addAttribute("typeName", typeName);
    return "policy-list";
}

@GetMapping("/advanced-search")
public String advancedSearchForm(Model model) {
    model.addAttribute("typeTree", policyTypeService.getSelectableTypeTree());
    model.addAttribute("queryDto", new PolicyQueryDto());
    return "advanced-search";
}

}
package com.example.policyquerysystem.repository;

import com.example.policyquerysystem.entity.Policy;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;

import java.util.Collections;
import java.util.List;

@Repository
public interface PolicyRepository extends JpaRepository<Policy, Long>, JpaSpecificationExecutor {

List<Policy> findByType(String type);
// 如果需要查詢該分類及其所有子分類的政策

@Query("SELECT p FROM Policy p WHERE p.type LIKE :typeId%")
List<Policy> findByTypeAndSubTypes(@Param("typeId") String typeId);

@Query("SELECT p FROM Policy p WHERE " +
        "(:name IS NULL OR p.name LIKE %:name%) AND " +
        "(:type IS NULL OR p.type = :type) AND " +
        "(:organ IS NULL OR p.organ LIKE %:organ%) AND " +
        "(:document IS NULL OR p.document LIKE %:document%) AND " +
        "(:text IS NULL OR p.text LIKE %:text%)")
List<Policy> advancedSearch(String name, String type, String organ, String document, String text);

// 通過分類名稱查詢
@Query("SELECT p FROM Policy p WHERE p.type = :typeName")
List<Policy> findByTypeName(@Param("typeName") String typeName);

// 通過分類ID查詢（先獲取名稱再查詢）
default List<Policy> findByTypeId(PolicyTypeRepository typeRepo, String typeId) {
    return typeRepo.findById(typeId)
            .map(type -> findByTypeName(type.getTypeName()))
            .orElse(Collections.emptyList());
}

}
package com.example.policyquerysystem.repository;

import com.example.policyquerysystem.entity.PolicyType;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public interface PolicyTypeRepository extends JpaRepository<PolicyType, String> {

List<PolicyType> findByParentIdIsNull();

List<PolicyType> findByParentId(String parentId);

@Query("SELECT t FROM PolicyType t WHERE t.typeName LIKE %:keyword%")
List<PolicyType> searchByKeyword(String keyword);

}
package com.example.policyquerysystem.service;

import com.example.policyquerysystem.dto.PolicyQueryDto;
import com.example.policyquerysystem.entity.Policy;
import com.example.policyquerysystem.repository.PolicyRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Service;

import javax.persistence.criteria.Predicate;
import java.util.ArrayList;
import java.util.List;

@Service
public class PolicyService {

@Autowired
private PolicyRepository policyRepository;

@Autowired
private PolicyTypeService policyTypeService;

public List<Policy> findByType(String typeId) {
    return policyRepository.findByType(typeId);
}
public List<Policy> advancedSearch(PolicyQueryDto queryDto) {
    return policyRepository.advancedSearch(
            queryDto.getName(),
            queryDto.getType(),
            queryDto.getOrgan(),
            queryDto.getDocument(),
            queryDto.getText()
    );
}

public List<Policy> advancedSearchWithSpecification(PolicyQueryDto queryDto) {
    return policyRepository.findAll((Specification<Policy>) (root, query, criteriaBuilder) -> {
        List<Predicate> predicates = new ArrayList<>();

        if (queryDto.getName() != null && !queryDto.getName().isEmpty()) {
            predicates.add(criteriaBuilder.like(root.get("name"), "%" + queryDto.getName() + "%"));
        }

        if (queryDto.getType() != null && !queryDto.getType().isEmpty()) {
            predicates.add(criteriaBuilder.equal(root.get("type"), queryDto.getType()));
        }

        if (queryDto.getOrgan() != null && !queryDto.getOrgan().isEmpty()) {
            predicates.add(criteriaBuilder.like(root.get("organ"), "%" + queryDto.getOrgan() + "%"));
        }

        if (queryDto.getDocument() != null && !queryDto.getDocument().isEmpty()) {
            predicates.add(criteriaBuilder.like(root.get("document"), "%" + queryDto.getDocument() + "%"));
        }

        if (queryDto.getText() != null && !queryDto.getText().isEmpty()) {
            predicates.add(criteriaBuilder.like(root.get("text"), "%" + queryDto.getText() + "%"));
        }

        return criteriaBuilder.and(predicates.toArray(new Predicate[0]));
    });
}

public Policy getPolicyById(Long id) {
    return policyRepository.findById(id).orElse(null);
}


public List<Policy> findByTypeName(String typeName) {
    return policyRepository.findByTypeName(typeName);
}

}
package com.example.policyquerysystem.service;

import com.example.policyquerysystem.dto.PolicyTypeTreeDTO;
import com.example.policyquerysystem.dto.TypeNodeDTO;
import com.example.policyquerysystem.entity.PolicyType;
import com.example.policyquerysystem.repository.PolicyTypeRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.*;
import java.util.stream.Collectors;

@Service
public class PolicyTypeService {

@Autowired
private PolicyTypeRepository policyTypeRepository;

public List<PolicyType> getRootTypes() {
    return policyTypeRepository.findByParentIdIsNull();
}

public List<PolicyType> getChildrenTypes(String parentId) {
    return policyTypeRepository.findByParentId(parentId);
}

public Map<String, List<PolicyType>> getTypeTree() {
    List<PolicyType> rootTypes = getRootTypes();
    Map<String, List<PolicyType>> typeTree = new HashMap<>();

    for (PolicyType rootType : rootTypes) {
        List<PolicyType> children = getChildrenTypes(rootType.getTypeId());
        typeTree.put(rootType.getTypeId(), children);
    }

    return typeTree;
}

public String getTypeNameById(String typeId) {
    return policyTypeRepository.findById(typeId)
            .map(PolicyType::getTypeName)
            .orElse("未知分類");
}

public List<PolicyType> searchTypes(String keyword) {
    return policyTypeRepository.searchByKeyword(keyword);
}
public Map<String, String> getAllTypeNames() {
    return policyTypeRepository.findAll()
            .stream()
            .collect(Collectors.toMap(PolicyType::getTypeId, PolicyType::getTypeName));
}

public Map<String, Object> getTypeTreeWithNames() {
    List<PolicyType> rootTypes = getRootTypes();
    Map<String, Object> typeTree = new LinkedHashMap<>();

    for (PolicyType rootType : rootTypes) {
        Map<String, Object> node = new HashMap<>();
        node.put("name", rootType.getTypeName());

        List<Map<String, String>> children = getChildrenTypes(rootType.getTypeId()).stream()
                .map(child -> {
                    Map<String, String> childMap = new HashMap<>();
                    childMap.put("id", child.getTypeId());
                    childMap.put("name", child.getTypeName());
                    return childMap;
                })
                .collect(Collectors.toList());

        node.put("children", children);
        typeTree.put(rootType.getTypeId(), node);
    }

    return typeTree;
}
public List<TypeNodeDTO> getTypeTreeAsDTO() {
    // 獲取所有根節點
    List<PolicyType> rootTypes = policyTypeRepository.findByParentIdIsNull();

    return rootTypes.stream()
            .map(root -> {
                TypeNodeDTO rootNode = new TypeNodeDTO(root);
                // 獲取子節點
                List<PolicyType> children = policyTypeRepository.findByParentId(root.getTypeId());
                rootNode.setChildren(
                        children.stream()
                                .map(TypeNodeDTO::new)
                                .collect(Collectors.toList())
                );
                return rootNode;
            })
            .collect(Collectors.toList());
}

private TypeNodeDTO convertToDTO(PolicyType policyType) {
    TypeNodeDTO dto = new TypeNodeDTO(policyType);
    List<PolicyType> children = getChildrenTypes(policyType.getTypeId());
    dto.setChildren(children.stream()
            .map(this::convertToDTO)
            .collect(Collectors.toList()));
    return dto;
}


    public List<PolicyTypeTreeDTO> getFullTypeTree() {
        // 獲取所有分類數據
        List<PolicyType> allTypes = policyTypeRepository.findAll();

        // 構建ID到DTO的映射
        Map<String, PolicyTypeTreeDTO> dtoMap = new HashMap<>();
        allTypes.forEach(type -> dtoMap.put(type.getTypeId(), new PolicyTypeTreeDTO(type)));

        // 構建樹形結構
        List<PolicyTypeTreeDTO> result = new ArrayList<>();
        for (PolicyType type : allTypes) {
            PolicyTypeTreeDTO dto = dtoMap.get(type.getTypeId());
            if (type.getParentId() == null || type.getParentId().isEmpty()) {
                result.add(dto);
            } else {
                PolicyTypeTreeDTO parentDto = dtoMap.get(type.getParentId());
                if (parentDto != null) {
                    parentDto.getChildren().add(dto);
                }
            }
        }

        return result;
    }
public List<PolicyTypeTreeDTO> getSelectableTypeTree() {
    List<PolicyTypeTreeDTO> fullTree = this.getFullTypeTree();

    // 確保所有節點都可選（包括一級分類）
    fullTree.forEach(root -> {
        root.setSelectable(true);
        root.getChildren().forEach(child -> child.setSelectable(true));
    });

    return fullTree;
}

}
package com.example.policyquerysystem;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class PolicyQuerySystemApplication {

public static void main(String[] args) {
    SpringApplication.run(PolicyQuerySystemApplication.class, args);
}

}