1、单文件下载

//文件下载测试
    @GetMapping("/download")
    public void fileDownload(HttpServletResponse response){
        //文件路径
        String filePath = "D:\\文件下载测试\\实验6打印.docx";
        //文件名
        String fileName = "实验6.docx";

        File file  = new File(filePath);

        //设置headers
        response.setHeader("Content-Type","application/octet-stream");
        //设置下载文件的名称，解决中文文件名乱码问题
        response.setHeader("Content-Disposition","attachment;filename="+ URLEncoder.encode(fileName, StandardCharsets.UTF_8));

        //创建流
        FileInputStream is = null;
        BufferedInputStream bs = null;
        ServletOutputStream os = null;

        //流到客户端
        try{
            is = new FileInputStream(file);
            bs =new BufferedInputStream(is);
            os = response.getOutputStream();
            byte[] buffer = new byte[1024];
            int len = 0;
            while((len = bs.read(buffer)) != -1){
                os.write(buffer,0,len);
            }
        }catch (IOException ex){
            ex.printStackTrace();
        }finally {
            try{
                if(is != null){
                    is.close();
                }
                if( bs != null ){
                    bs.close();
                }
                if( os != null){
                    os.flush();
                    os.close();
                }
            }catch (IOException e){
                e.printStackTrace();
            }
        }

    }

2、多文件下载

//文件打包下载测试
    @GetMapping("/download/package")
    public void compressedDownload(HttpServletResponse response){
        //伪造文件名数组
        String[] names = {"10.png","实验报告.docx"};
        //伪造文件所在路径数组
        String[] paths = {"D:\\文件下载测试\\6z10.png","D:\\文件下载测试\\实验6打印.docx"};

        //创建临时目录以存放生成的压缩包文件
        String directory = "D:\\文件压缩包临时目录";
        File directoryFile = new File(directory);

        //设置最终输出zip文件的目录+文件名
        SimpleDateFormat formatter  = new SimpleDateFormat("yyyy年MM月dd日HH时mm分ss秒");
        String zipFileName = formatter.format(new Date())+".zip";
        String strZipPath = directory+"\\"+zipFileName;

        //创建流
        ZipOutputStream zipStream = null;
        FileInputStream zipSource = null;
        BufferedInputStream bufferStream = null;
        File zipFile = new File(strZipPath);
        try{
            //构造最终压缩包的输出流
            zipStream = new ZipOutputStream(new FileOutputStream(zipFile));
            for(int i = 0; i<paths.length ;i++){
                //解码获取真实路径与文件名
                String realFileName = java.net.URLDecoder.decode(names[i],"UTF-8");
                String realFilePath = java.net.URLDecoder.decode(paths[i],"UTF-8");
                File file = new File(realFilePath);
                if(file.exists()){
                    zipSource = new FileInputStream(file);//将需要压缩的文件格式化为输入流
                    ZipEntry zipEntry = new ZipEntry(realFileName);//在压缩目录中文件的名字
                    zipStream.putNextEntry(zipEntry);//定位该压缩条目位置，开始写入文件到压缩包中
                    bufferStream = new BufferedInputStream(zipSource, 1024 * 10);
                    int read = 0;
                    byte[] buf = new byte[1024 * 10];
                    while((read = bufferStream.read(buf, 0, 1024 * 10)) != -1){
                        zipStream.write(buf, 0, read);
                    }
                }
            }

        }catch(Exception e){
            e.printStackTrace();
        }finally {
            //关闭流
            try{
                if(null != bufferStream) bufferStream.close();
                if(null != zipStream){
                    zipStream.flush();
                    zipStream.close();
                }
                if(null != zipSource) zipSource.close();
            }catch (IOException exception){
                exception.printStackTrace();
            }
        }

        if(zipFile.exists()){
            downImg(response,zipFileName,strZipPath);
            zipFile.delete();
        }
    }
    
    public void downImg(HttpServletResponse response,String filename,String path ){
        if (filename != null) {
            FileInputStream is = null;
            BufferedInputStream bs = null;
            OutputStream os = null;
            try {
                File file = new File(path);
                if (file.exists()) {
                    //设置Headers
                    response.setHeader("Content-Type","application/octet-stream");
                    //设置下载的文件的名称-该方式已解决中文乱码问题
                    response.setHeader("Content-Disposition","attachment;filename=" +  new String( filename.getBytes("gb2312"), "ISO8859-1" ));
                    is = new FileInputStream(file);
                    bs =new BufferedInputStream(is);
                    os = response.getOutputStream();
                    byte[] buffer = new byte[1024];
                    int len = 0;
                    while((len = bs.read(buffer)) != -1){
                        os.write(buffer,0,len);
                    }
                }else{
                    String error = Base64Util.encode("下载的文件资源不存在");
                    response.sendRedirect("/imgUpload/imgList?error="+error);
                }
            }catch(IOException ex){
                ex.printStackTrace();
            }finally {
                try{
                    if(is != null){
                        is.close();
                    }
                    if( bs != null ){
                        bs.close();
                    }
                    if( os != null){
                        os.flush();
                        os.close();
                    }
                }catch (IOException e){
                    e.printStackTrace();
                }
            }
        }
    }