Java web实现文件打包下载功能（转载）

转自：https://blog.csdn.net/onesilver/article/details/78181745

首先需要实现一个文件打包下载的辅助类

public class CustomFileUtil {

    /** 
     *  
     * @param inputFileName 
     *            输入一个文件夹 
     * @param zipFileName 
     *            输出一个压缩文件夹，打包后文件名字 
     * @throws Exception 
     */  
    public static void zip(String inputFileName, String zipFileName) throws Exception {  
        zip(zipFileName, new File(inputFileName));  
    }  

    private static void zip(String zipFileName, File inputFile) throws Exception {  
        ZipOutputStream out = new ZipOutputStream(new FileOutputStream(zipFileName));  
        zip(out, inputFile, "");  
        out.close();  
    }  

    private static void zip(ZipOutputStream out, File f, String base) throws Exception {  
        if (f.isDirectory()) { // 判断是否为目录  
            File[] fl = f.listFiles();  
            out.putNextEntry(new ZipEntry(base + "/"));  
            base = base.length() == 0 ? "" : base + "/";  
            for (int i = 0; i < fl.length; i++) {  
                zip(out, fl[i], base + fl[i].getName());  
            }  
        } else { // 压缩目录中的所有文件  
            out.putNextEntry(new ZipEntry(base));  
            FileInputStream in = new FileInputStream(f);  
            int b;  
            while ((b = in.read()) != -1) {  
                out.write(b);
            }  
            in.close();  
        }  
    }  

    /** 
     * 下载文件 
     *  
     * @param file 文件路径
     * @param response 
     * @param isDelete 是否删除生成的压缩包
     */  
    public static void downloadFile(File file,HttpServletResponse response,boolean isDelete) {
        try {
            // 以流的形式下载文件。
            BufferedInputStream fis = new BufferedInputStream(new FileInputStream(file.getPath()));
            byte[] buffer = new byte[fis.available()];
            fis.read(buffer);
            fis.close();
            // 清空response
            response.reset();
            OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
            response.setContentType("application/octet-stream");
            response.setHeader("Content-Disposition", "attachment;filename=" + new String(file.getName().getBytes("UTF-8"),"ISO-8859-1"));
            toClient.write(buffer);
            toClient.flush();
            toClient.close();
            if(isDelete)
            {
                file.delete();        //是否将生成的服务器端文件删除
            }
         } 
         catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    public static void zipFile(List<File> files, ZipOutputStream outputStream) throws IOException, ServletException {
        try {
            int size = files.size();
            // 压缩列表中的文件
            for (int i = 0; i < size; i++) {
                File file = (File) files.get(i);
                zipFile(file, outputStream);
            }
        } catch (IOException e) {
            throw e;
        }
    }
    public static void zipFile(File inputFile, ZipOutputStream outputstream) throws IOException, ServletException {
        try {
            if (inputFile.exists()) {
                if (inputFile.isFile()) {
                    FileInputStream inStream = new FileInputStream(inputFile);
                    BufferedInputStream bInStream = new BufferedInputStream(inStream);
                    ZipEntry entry = new ZipEntry(inputFile.getName());
                    outputstream.putNextEntry(entry);

                    final int MAX_BYTE = 10 * 1024 * 1024; // 最大的流为10M
                    long streamTotal = 0; // 接受流的容量
                    int streamNum = 0; // 流需要分开的数量
                    int leaveByte = 0; // 文件剩下的字符数
                    byte[] inOutbyte; // byte数组接受文件的数据

                    streamTotal = bInStream.available(); // 通过available方法取得流的最大字符数
                    streamNum = (int) Math.floor(streamTotal / MAX_BYTE); // 取得流文件需要分开的数量
                    leaveByte = (int) streamTotal % MAX_BYTE; // 分开文件之后,剩余的数量

                    if (streamNum > 0) {
                        for (int j = 0; j < streamNum; ++j) {
                            inOutbyte = new byte[MAX_BYTE];
                            // 读入流,保存在byte数组
                            bInStream.read(inOutbyte, 0, MAX_BYTE);
                            outputstream.write(inOutbyte, 0, MAX_BYTE); // 写出流
                        }
                    }
                    // 写出剩下的流数据
                    inOutbyte = new byte[leaveByte];
                    bInStream.read(inOutbyte, 0, leaveByte);
                    outputstream.write(inOutbyte);
                    outputstream.closeEntry(); // Closes the current ZIP entry
                    // and positions the stream for
                    // writing the next entry
                    bInStream.close(); // 关闭
                    inStream.close();
                }
            } else {
                throw new ServletException("文件不存在！");
            }
        } catch (IOException e) {
            throw e;
        }
    }
}

控制器实现下载功能，其中File.separatorChar是File类的静态字段，由于windows系统和linux系统下的路径分割符是不一样的，所以在此使用File.separatorChar，来默认在windows中为\分隔符,Linux下为/分割符

@RequestMapping(value ="/BatchDownload", method = RequestMethod.GET)
@ResponseBody
public void BatchDownload(
    @RequestParam(value = "ids", required = true) String ids,
    HttpServletRequest request, HttpServletResponse response)  throws ServletException, IOException{
    //文件路径最后带分隔符"/"
    String inputFileName = request.getSession().getServletContext().getRealPath("upload")+File.separatorChar+"qrcode"+File.separatorChar+ids+File.separatorChar; 
       List<File> files = new ArrayList<File>();
       File Allfile = new File(inputFileName);
       if (Allfile.exists()) {
           File[] fileArr = Allfile.listFiles();
           for (File file2 : fileArr) {
               files.add(file2);
           }
       } 
       //压缩包名字
       String fileName =this_ResListService.selectById(ids).getName()+".zip";
       // 在服务器端创建打包下载的临时文件
       String outFilePath = inputFileName;
       File fileZip = new File(outFilePath + fileName);
       FileOutputStream outStream = new FileOutputStream(fileZip); // 文件输出流
       ZipOutputStream toClient = new ZipOutputStream(outStream);// 压缩流
       CustomFileUtil.zipFile(files, toClient);
       outStream.close();
       CustomFileUtil.downloadFile(fileZip, response, true);   
}

最后需要在前台请求打包下载，在这也把代码贴上

/*批量下载二维码*/
function BatchDownload()
{
    var url='/ResSeat/BatchDownload.do?ids='+resrantid;
    if(url){
       location.href = url;
    }
}

前台请求时一定注意，一定要写上

location.href = url;  //如果不写这一行代码，打包的文件只会缓存在Response里，不会下载下来

贴代码的原因，也是如此，作为一个新手，我第一次实现打包下载功能时，前台是用ajax请求的，并且没有跳转，来来去去修改了好几次打包下载的后台代码，最后打开浏览器查看才发现，文件是缓存到浏览器了，但是没有跳转下载。
至此，打包下载的功能已完全实现，适用于所有文件。