refactor: 根包由 com.bestsch.bschclassmanage 重命名为 com.yunhai.bschclassmanage

- git mv src/main/java/com/bestsch/bschclassmanage -> src/main/java/com/yunhai/bschclassmanage
- 255 个 Java 文件的 package/import 同步替换为 com.yunhai.bschclassmanage
- pom.xml 项目 groupId 设为 com.yunhai（与外部依赖 com.bestsch:bsch-* 无关，未改动）
- IDE 缓存 workspace.xml 路径同步更新（外部依赖坐标 com.bestsch:bsch-* 保持不动）

src/main/java/com/yunhai/bschclassmanage/utils/DownloadFileUtil.java

@@ -0,0 +1,56 @@
+package com.yunhai.bschclassmanage.utils;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.core.io.InputStreamResource;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+
+import java.io.*;
+
+@Slf4j
+public class DownloadFileUtil {
+
+    public static final String separator = File.separator;
+
+    /**
+     * 下载样表
+     * @param filePath 文件上级目录
+     * @param fileName 文件名
+     * @param newName  下载的展示文件名
+     * @return 响应
+     */
+    public static ResponseEntity<InputStreamResource> download(String filePath, String fileName, String newName) {
+//        String route = "static" + separator + "templates" + separator;
+//        String path = null;
+        ResponseEntity<InputStreamResource> response = null;
+        try {
+//            path = route + filePath + separator + fileName;
+
+            File file = new File(filePath);
+
+            System.out.println(file.exists());
+
+
+//            ClassPathResource classPathResource = new ClassPathResource(filePath);
+            InputStream inputStream = new FileInputStream(file);
+
+            HttpHeaders headers = new HttpHeaders();
+            headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
+            headers.add("Content-Disposition",
+                    "attachment; filename="
+                            + new String(newName.getBytes("gbk"), "iso8859-1"));
+            headers.add("Pragma", "no-cache");
+            headers.add("Expires", "0");
+            response = ResponseEntity.ok().headers(headers)
+                    .contentType(MediaType.parseMediaType("application/octet-stream"))
+                    .body(new InputStreamResource(inputStream));
+        } catch (FileNotFoundException e1) {
+            log.error("找不到指定的文件", e1);
+        } catch (IOException e) {
+            log.error("获取不到文件流", e);
+        }
+        return response;
+    }
+}
+