feat: 增加获取流域树形结构

backend/src/main/java/com/yfd/platform/env/controller/SdRvcdDicController.java

@@ -71,6 +71,14 @@ public class SdRvcdDicController {
         return ResponseResult.successData(rvcdDicService.getById(rvcd));
     }
 
+    @GetMapping("/tree")
+    @Operation(summary = "获取流域树形结构")
+    public ResponseResult getTree(
+            @RequestParam(required = false) String rvcd,
+            @RequestParam(required = false) String rvnm) {
+        return ResponseResult.successData(rvcdDicService.getTree(rvcd, rvnm));
+    }
+
 //    @Log(module = "流域管理", value = "新增流域")
     @PostMapping("/add")
     @Operation(summary = "新增流域")

backend/src/main/java/com/yfd/platform/env/domain/SdRvcdDic.java

@@ -6,6 +6,7 @@ import lombok.EqualsAndHashCode;
 
 import java.io.Serializable;
 import java.util.Date;
+import java.util.List;
 
 /**
  * <p>
@@ -114,4 +115,10 @@ public class SdRvcdDic implements Serializable {
      * 地图专题流域标识：1=是 0否
      */
     private Integer ismap;
+
+    /**
+     * 子节点（用于树形结构，不映射数据库字段）
+     */
+    @TableField(exist = false)
+    private List<SdRvcdDic> children;
 }

backend/src/main/java/com/yfd/platform/env/service/ISdRvcdDicService.java

@@ -42,4 +42,11 @@ public interface ISdRvcdDicService extends IService<SdRvcdDic> {
      * 删除流域
      */
     boolean deleteRvcdDic(String rvcd);
+
+    /**
+     * 获取流域树形结构
+     * @param rvcd 流域编码（可选，为空则返回全部）
+     * @param rvnm 流域名称（可选，用于模糊搜索）
+     */
+    List<SdRvcdDic> getTree(String rvcd, String rvnm);
 }

backend/src/main/java/com/yfd/platform/env/service/impl/SdRvcdDicServiceImpl.java

@@ -6,8 +6,10 @@ import com.yfd.platform.env.domain.SdRvcdDic;
 import com.yfd.platform.env.mapper.SdRvcdDicMapper;
 import com.yfd.platform.env.service.ISdRvcdDicService;
 import org.springframework.stereotype.Service;
+import org.springframework.util.StringUtils;
 
-import java.util.List;
+import java.util.*;
+import java.util.stream.Collectors;
 
 /**
  * <p>
@@ -58,4 +60,58 @@ public class SdRvcdDicServiceImpl extends ServiceImpl<SdRvcdDicMapper, SdRvcdDic
     public boolean deleteRvcdDic(String rvcd) {
         return this.removeById(rvcd);
     }
-}
+
+    @Override
+    public List<SdRvcdDic> getTree(String rvcd, String rvnm) {
+        List<SdRvcdDic> result = new ArrayList<>();
+
+        List<SdRvcdDic> rootList;
+        Set<String> rootRvcdSet = new HashSet<>();
+
+        if (StringUtils.hasText(rvcd)) {
+            SdRvcdDic singleRvcd = this.getById(rvcd);
+            if (singleRvcd != null) {
+                rootList = new ArrayList<>();
+                rootList.add(singleRvcd);
+                rootRvcdSet.add(singleRvcd.getRvcd());
+            } else {
+                return result;
+            }
+        } else {
+            rootList = getRootList();
+            for (SdRvcdDic root : rootList) {
+                rootRvcdSet.add(root.getRvcd());
+            }
+        }
+
+        List<SdRvcdDic> allList = this.lambdaQuery()
+                .like(StringUtils.hasText(rvnm), SdRvcdDic::getRvnm, rvnm)
+                .orderByAsc(SdRvcdDic::getOrderIndex)
+                .list();
+
+        Map<String, List<SdRvcdDic>> childrenMap = allList.stream()
+                .filter(item -> item.getPrvcd() != null)
+                .collect(Collectors.groupingBy(SdRvcdDic::getPrvcd));
+
+        for (SdRvcdDic root : rootList) {
+            if (rootRvcdSet.contains(root.getRvcd())) {
+                buildTreeRecursive(root, childrenMap, rootRvcdSet);
+                result.add(root);
+            }
+        }
+
+        return result;
+    }
+
+    private void buildTreeRecursive(SdRvcdDic parent, Map<String, List<SdRvcdDic>> childrenMap, Set<String> rootRvcdSet) {
+        List<SdRvcdDic> children = childrenMap.get(parent.getRvcd());
+        if (children != null && !children.isEmpty()) {
+            for (SdRvcdDic child : children) {
+                buildTreeRecursive(child, childrenMap, rootRvcdSet);
+            }
+            parent.setChildren(children);
+        } else {
+            parent.setChildren(new ArrayList<>());
+        }
+    }
+}