Java Springboot 根据图片链接生成图片下载链接 及 多个图片打包zip下载链接

现有一些图片在服务器上的链接，在浏览器中打开这些链接是直接显示在浏览器页面的形式。

现在需要生成这些图片的单独下载以及打包下载链接，即在浏览器中打开下载链接后弹出下载框提示下载。由于前端存在跨域问题，所以图片下载由后台接口完成。

首先编写文件下载工具类：

 import java.net.URL;
 import java.net.MalformedURLException;
 import org.apache.commons.io.FileUtils;

 public class FileDownloadUtil {
 /**
      * 下载文件---返回下载后的文件存储路径
      *
      * @param url 文件路径
     * @param dir 目标存储目录
     * @param fileName 存储文件名
     * @return
     */
    public static void downloadHttpUrl(String url, String dir, String fileName) throws BusinessException {
        try {
        URL httpurl = new URL(url);
        File dirfile = new File(dir);
            if (!dirfile.exists()) {
                dirfile.mkdirs();
            }
            FileUtils.copyURLToFile(httpurl, new File(dir+fileName));
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();26         }
    }

     public static boolean deleteFile(File file) {
         if (file.exists()) {
             return file.delete();
         }
         return false;
     }
 ｝

单张图片下载

Controller层接口：

 import org.apache.commons.lang.StringUtils;
 import java.io.*;

 protected HttpServletResponse response;

 /**
      * 单张图片下载
      *
      * @param url 要下载的图片url
      * @author: nemowang
      */
     @ApiImplicitParams({
             @ApiImplicitParam(name = "url", value = "图片url", required = true, dataType = "String", paramType = "query"),
     })
     @ApiOperation(value = "单张图片下载", notes = "单张图片下载")
     @RequestMapping(value = "/downloadPicture", method = RequestMethod.GET)
     public void downloadPicture(String url) {

         // 拼接完整图片路径。这里填写图片链接
         String urlPath = "";

         // 获取图片文件后缀名
         String postfix = "." + StringUtils.substringAfterLast(url, ".");

         // 获取当前类的所在项目路径
         File directory = new File("");
         String courseFile;

         String srcPath;
         File srcFile = null;
         FileInputStream fileInputStream = null;
         InputStream fis = null;
         OutputStream out = null;
         try {
             courseFile = directory.getCanonicalPath();
             String fileName = "\\" + StringUtil.getUUID() + postfix;
             // 下载文件
             FileDownloadUtil.downloadHttpUrl(urlPath, courseFile, fileName);

             srcPath = courseFile + fileName;
             srcFile = new File(srcPath);

             fileInputStream = new FileInputStream(srcPath);
             fis = new BufferedInputStream(fileInputStream);
             byte[] buffer = new byte[fis.available()];
             fis.read(buffer);

             response.setContentType("application/octet-stream");
             response.setHeader("Content-disposition", "attachment;filename=" + fileName);
             out = response.getOutputStream();
             out.write(buffer);
             out.flush();
             out.close();
         } catch (Exception e) {
             e.printStackTrace();
         } finally {
             try {
                 if (fileInputStream != null) {
                     fileInputStream.close();
                 }
                 if (fis != null) {
                     fis.close();
                 }
                 if (out != null) {
                     out.close();
                 }
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }

         // 删除中间文件
         if (srcFile != null) {
             System.out.println(FileDownloadUtil.deleteFile(srcFile));
         }
     }

因为是GET请求，所以直接拼接接口路由+参数，用浏览器打开就能弹出下载。

至此单张图片下载接口结束。

多张图片打包下载

Controller层接口：

 /**
      * 图片打包下载
      */
     @ApiImplicitParams({
             @ApiImplicitParam(name = "urls", value = "图片url列表", required = true, dataType = "List", paramType = "query"),
     })
     @ApiOperation(value = "图片打包下载", notes = "图片打包下载")
     @RequestMapping(value = "/downloadPictureList", method = RequestMethod.GET)
     public void downloadPictureList(List urls) {
         List<String> fileNameList = new ArrayList<>();

         for (int i = 0; i < urls.size(); i++) {
             // 获取文件名
             fileNameList.add(StringUtils.substringAfterLast(urls.get(i), "/"));

             // 拼接完整图片路径
             urls.set(i, DOMAIN + urls.get(i));
         }

         // 获取当前类的所在项目路径
         File directory = new File("");
         String courseFile;

         String srcPath;
         File srcFile = null;

         // 要打包的文件列表
         List<File> fileList = new ArrayList<>();

         ZipOutputStream zos = null;
         OutputStream out = null;
         try {
             courseFile = directory.getCanonicalPath();

             // 下载文件
             for (int i = 0; i < urls.size(); i++) {
                 String fileName = "\\" + fileNameList.get(i);
                 FileDownloadUtil.downloadHttpUrl(urls.get(i), courseFile, fileName);
                 srcPath = courseFile + fileName;
                 srcFile = new File(srcPath);
                 fileList.add(srcFile);
             }

             long start = System.currentTimeMillis();

             response.setContentType("application/x-zip-compressed");
             response.setHeader("Content-disposition", "attachment;filename=" + StringUtil.getUUID() + ".zip");
             out = response.getOutputStream();
             zos = new ZipOutputStream(out);
             for (File file : fileList) {
                 byte[] buf = new byte[BUFFER_SIZE];
                 zos.putNextEntry(new ZipEntry(file.getName()));
                 int len;
                 FileInputStream in = new FileInputStream(file);
                 while ((len = in.read(buf)) != -1) {
                     zos.write(buf, 0, len);
                 }
                 zos.closeEntry();
                 in.close();
             }
             long end = System.currentTimeMillis();
             System.out.println("压缩完成，耗时：" + (end - start) + " ms");

             out.flush();
         } catch (IOException e) {
             e.printStackTrace();
         } catch (Exception e) {
                 throw new RuntimeException("zip error from ZipUtils", e);
         } finally {
             if (zos != null) {
                 try {
                     zos.close();
                 } catch (IOException e) {
                     e.printStackTrace();
                 }
             }
             if (out != null) {
                 try {
                     zos.close();
                 } catch (IOException e) {
                     e.printStackTrace();
                 }
             }
         }

         // 删除中间文件
         if (fileList != null) {
             for (File file : fileList) {
                 System.out.println(FileDownloadUtil.deleteFile(file));
             }
         }
     }

同样是GET请求，所以也是拼接接口路由+参数，用浏览器打开就能弹出下载。