Java web实现文件打包下载功能（转载）

Dear 丶 2023-02-18 08:20 42阅读 0赞

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。