java spring boot 导出/下载文本文件操作（包含写文本文件）

内容简介

本文主要内容为使用java把内容写入文本文件，并实现下载/导出的功能。

实现步骤

1. controller层

    @ResponseBody
    @RequestMapping(value = "/exportLand2ndClassIndex", method = RequestMethod.GET)
    public ResponseEntity<byte[]> exportLand2ndClassIndex(){
        return extractTifService.exportLand2ndClassIndex();
    }

2. 服务实现层，请自行定义服务接口，这里不展示了

    /**
     * 导出
     * @return CallbackBody
     */
    @Override
    public ResponseEntity<byte[]> exportLand2ndClassIndex(){
        //查询表数据
        List<TswatLuc2ndClassIndex> list = tswatLuc2ndClassIndexDao.queryAllClassIndex();
        if (list == null || list.size() <= 0){
            return null;
        }
        List txtContentList = new ArrayList();
        txtContentList.add("\"value\",\"name\"");
        for(TswatLuc2ndClassIndex classIndex : list){
            String value = classIndex.getLevel2Code();
            String name = classIndex.getSwat();
            txtContentList.add(value + "," + name);
        }
        //导出的文件存储目录
        String fileSavePath = GisPathConfigurationUtil.getSwatLuc2ndClassIndexTxtFileSavePath();
        //保存文本文件
        writeToTxt(txtContentList, fileSavePath);
        //获取文本文件的ResponseEntity
        try{
            ResponseEntity<byte[]> fileByte = buildResponseEntity(new File(fileSavePath));
            return fileByte;
        }catch (Exception e){
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 将数据写入文本文件
     * @param list
     * @param path
     */
    private void writeToTxt(List list,String path) {

        String dir = path.substring(0,path.lastIndexOf("\\"));
        File parent = new File(dir);
        if (parent != null && !parent.exists()) {
            parent.mkdirs();
        }
        FileOutputStream outSTr = null;
        BufferedOutputStream Buff = null;
        String enter = "\r\n";
        StringBuffer write ;
        try {
            outSTr = new FileOutputStream(new File(path));
            Buff = new BufferedOutputStream(outSTr);
            for (int i = 0; i < list.size(); i++) {
                write = new StringBuffer();
                write.append(list.get(i));
                write.append(enter);
                Buff.write(write.toString().getBytes("UTF-8"));
            }
            Buff.flush();
            Buff.close();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                Buff.close();
                outSTr.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    //读取文件
    private ResponseEntity<byte[]> buildResponseEntity(File file) throws IOException {
        byte[] body = null;
        //获取文件
        InputStream is = new FileInputStream(file);
        body = new byte[is.available()];
        is.read(body);
        HttpHeaders headers = new HttpHeaders();
        //设置文件类型
        headers.add("Content-Disposition", "attchement;filename=" + file.getName());
        //设置Http状态码
        HttpStatus statusCode = HttpStatus.OK;
        //返回数据
        ResponseEntity<byte[]> entity = new ResponseEntity<byte[]>(body, headers, statusCode);
        return entity;
    }