新增文件下载功能

know_sub_business/src/main/java/com/supervision/knowsub/controller/FileController.java

@@ -3,6 +3,7 @@ package com.supervision.knowsub.controller;
 import com.supervision.knowsub.service.FileService;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.servlet.http.HttpServletResponse;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.web.bind.annotation.*;
@@ -31,4 +32,12 @@ public class FileController {
     public void deleteFileById(String fileId){
         fileService.deleteFileById(fileId);
     }
+
+    @Operation(summary = "下载文件")
+    @GetMapping("/downloadFile")
+    public void downloadFile(@RequestParam String fileId, HttpServletResponse response) {
+
+        fileService.downloadFile(fileId, response);
+
+    }
 }

know_sub_business/src/main/java/com/supervision/knowsub/service/FileService.java

@@ -1,7 +1,7 @@
 package com.supervision.knowsub.service;
 
 import com.supervision.knowsub.model.FileInfo;
-import org.springframework.web.multipart.MultipartFile;
+import jakarta.servlet.http.HttpServletResponse;
 
 import java.util.List;
 
@@ -12,4 +12,6 @@ public interface FileService {
     void deleteFileById(String fileId);
 
     List<FileInfo> listByFileId(List<String> fileIdList);
+
+    void downloadFile(String fileId, HttpServletResponse response);
 }

know_sub_business/src/main/java/com/supervision/knowsub/service/impl/FileServiceImpl.java

@@ -1,22 +1,26 @@
 package com.supervision.knowsub.service.impl;
 
 import cn.hutool.core.collection.CollUtil;
-import cn.hutool.core.convert.Convert;
 import cn.hutool.core.io.FileUtil;
 import cn.hutool.core.io.unit.DataSizeUtil;
+import cn.hutool.core.lang.Assert;
 import cn.hutool.core.util.ObjectUtil;
-import com.baomidou.mybatisplus.annotation.TableField;
+import cn.hutool.core.util.StrUtil;
+import com.supervision.knowsub.exception.BusinessException;
 import com.supervision.knowsub.model.FileBlob;
 import com.supervision.knowsub.model.FileInfo;
 import com.supervision.knowsub.service.FileBlobService;
 import com.supervision.knowsub.service.FileInfoService;
 import com.supervision.knowsub.service.FileService;
+import jakarta.servlet.ServletOutputStream;
+import jakarta.servlet.http.HttpServletResponse;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
-import java.math.BigDecimal;
+import java.net.URLEncoder;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -68,4 +72,27 @@ public class FileServiceImpl implements FileService {
         }
         return fileInfoService.lambdaQuery().in(FileInfo::getId, fileIdList).list();
     }
+
+    @Override
+    public void downloadFile(String fileId, HttpServletResponse response) {
+        Assert.notEmpty(fileId, "文件id不能为空");
+
+        FileInfo fileInfo = fileInfoService.getById(fileId);
+        Assert.notNull(fileInfo, "文件不存在");
+        FileBlob fileBlob = fileBlobService.getById(fileInfo.getFileBlobId());
+        Assert.notNull(fileBlob, "文件内容不存在");
+
+        if (StrUtil.isNotEmpty(fileInfo.getFileName())){
+            response.setHeader("Content-Disposition", "attachment;filename=" +
+                    URLEncoder.encode(fileInfo.getFileName(), StandardCharsets.UTF_8));
+        }
+        try (ServletOutputStream outputStream = response.getOutputStream()){
+            response.setContentType("application/octet-stream");
+            outputStream.write(fileBlob.getBlobByte());
+            outputStream.flush();
+        }catch (Exception e){
+            log.error("文件下载失败",e);
+            throw new BusinessException("下载文件失败",e);
+        }
+    }
 }