1. 讀取txt檔案：

使用ClassPathResource的原因在https://blog.csdn.net/nnnora/article/details/80734326中闡述過，因為是springboot內建web容器所以不能使用FileInputStream的方式獲取檔案流。

            //讀取txt檔案
            ClassPathResource classPathResource = new ClassPathResource("test.txt");
            InputStreamReader inputStreamReader = new InputStreamReader(classPathResource.getInputStream());
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            StringBuffer buffer = new StringBuffer();
            String line = null;
            while( (line = bufferedReader.readLine()) != null ){
                buffer.append(line);
            }
            bufferedReader.close();
            String buffer = buffer.toString();
 

2. 寫入txt檔案：

            //寫入txt
            BufferedWriter bufw = new BufferedWriter(new FileWriter("D:\\test\\result.txt"));
            for(Map.Entry<String, Integer> me : list){
                bufw.write(me+"");
                bufw.newLine();
            }
            bufw.close();

3. 讀取word文件

1. 首先需要引入以下jar包：

分別是操作doc和docx格式需要的jar包，關於引入jar包的語句格式可以去http://jareye.com/查詢，可以匯出maven或者gradle等工具下的compile語句。

2. 讀取word文件：

        try {
            //讀取word檔案
            String path = "Shocking level of sexual harassment at music festivals.docx";
            String buffer = "";
            if (path.endsWith(".doc")) {
                ClassPathResource classPathResource = new ClassPathResource(path);
                WordExtractor wordExtractor = new WordExtractor(classPathResource.getInputStream());
                buffer = wordExtractor.getText();
            } else if (path.endsWith("docx")) {
                ClassPathResource classPathResource = new ClassPathResource(path);
                XWPFDocument xdoc = new XWPFDocument(classPathResource.getInputStream());
                POIXMLTextExtractor extractor = new XWPFWordExtractor(xdoc);
                buffer = extractor.getText();
            } else {
                System.out.println("此檔案不是word檔案！");
            }
        }catch (Exception e){
            logger.error("@@ReadFileError", e);
        }
 

4. 寫入excel文件

            //寫入excel
            //第一步，建立一個workbook對應一個excel檔案
            HSSFWorkbook workbook = new HSSFWorkbook();
            //第二步，在workbook中建立一個sheet對應excel中的sheet
            HSSFSheet sheet = workbook.createSheet("詞頻檔案");
            //第三步，在sheet表中新增表頭第0行，老版本的poi對sheet的行列有限制
            HSSFRow row = sheet.createRow(0);
            //第四步，建立單元格，設定表頭
            HSSFCell cell = row.createCell(0);
            cell.setCellValue("單詞");
            cell = row.createCell(1);
            cell.setCellValue("頻次");

            //第五步，寫入實體資料
            int i = 0;
            for(Map.Entry<String, Integer> entity : list){
                HSSFRow row1 = sheet.createRow(i + 1);
                row1.createCell(0).setCellValue(entity.getKey());
                row1.createCell(1).setCellValue(entity.getValue());
                i++;
            }
            //將檔案儲存到指定的位置
            try {
                fos = new FileOutputStream("wordsResult.xls");
                workbook.write(fos);
                logger.info("寫入成功");
                fos.close();
            } catch (IOException e) {
                logger.error("@@WriteFileError", e);
            }