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。