java下載模板文件

1. 在pom.xml中引入 poi 和common-io的包

<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 -->
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-lang3</artifactId>
      <version>3.9</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/commons-io/commons-io -->
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.6</version>
    </dependency>

    <dependency>
      <groupId>org.apache.poi</groupId>
      <artifactId>poi-ooxml</artifactId>
      <version>3.14</version>
    </dependency>

2. 在resourse文件夾下引入文件
   

3. 在項目啓動時，獲得模板文件的相關信息

@Component
@Slf4j
public class ProjectConfiguration {

  @Autowired
  private ResourceLoader resourceLoader;

  public  byte[] fileBytes;
  public  String fileName;

  @PostConstruct
  public void init(){
    log.info("在啓動方法之前執行");
    Resource resource = resourceLoader.getResource("classpath:template/customer_template.xls");
    try {
      InputStream inputStream = resource.getInputStream();
      fileName = "customer_template.xls";
      fileBytes = IOUtils.toByteArray(inputStream);

      log.info("byte:{}",fileBytes);
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

4. 引入文件工具類 ExcelUtils

/**
 * @Description: excel 處理工具類
 */
public class ExcelUtils {

  private static final Pattern NUMBER_PATTERN = Pattern.compile("[-]?[\\d.]+");
  private static final FastDateFormat FDF = FastDateFormat.getInstance("yyyy-MM-dd HH:mm:ss");
  private static final DecimalFormat DF = new DecimalFormat("0.00");


  public static SXSSFWorkbook createWorkBook(String sheetName, List<String> titles,
      List<List> contents) throws Exception {

    SXSSFWorkbook wb = new SXSSFWorkbook();
    SXSSFSheet sheet = null;

    // 對每個表生成一個新的sheet,並以表名命名
    if (sheetName == null) {
      sheetName = "sheet1";
    }
    sheet = wb.createSheet(sheetName);
    sheet.setDefaultColumnWidth(10 * 256);
    // 設置表頭的說明
    SXSSFRow topRow = sheet.createRow(0);
    for (int i = 0; i < titles.size(); i++) {
      setCellGBKValue(topRow.createCell(i), titles.get(i));
      sheet.setColumnWidth(i, titles.get(i).getBytes().length * 258);
    }

    XSSFCellStyle wrapStyle = (XSSFCellStyle) wb.createCellStyle();
    // 設置單元格內容是否自動換行
    wrapStyle.setWrapText(true);

    Map columnWidth = new HashMap<Integer, Integer>();
    for (int i = 0; i < contents.size(); i++) {
      List one = contents.get(i);
      SXSSFRow row = sheet.createRow(i + 1);
      // 行高
      int height = 1;
      for (int j = 0; j < titles.size(); j++) {
        Object cellValue = one.get(j);
        /**
         * 數字按照數字樣式處理 2018/1/18 王斌
         */
        if (cellValue == null) {
          setCellGBKValue(row.createCell(j), "");
        } else {
          String cellStringValue = cellValue.toString();
          SXSSFCell cell = row.createCell(j);
          /*if (NUMBER_PATTERN.matcher(cellStringValue).matches()
              && cellStringValue.length() < 11) {// 非11位的數字、設置數字格式
            setCellGBKValue(cell, Double.valueOf(cellStringValue));
          } else {
            setCellGBKValue(cell, cellStringValue);
          }*/
          setCellGBKValue(cell, cellStringValue);
          if (cellStringValue.length() > 4) {// 內容長度大於4做自適應處理
            int width = (cellStringValue.getBytes().length + 4) * 256;
            sheet.setColumnWidth(j, width < 3000 ? 3000 : width < 255 * 256 ? width : 6000);
            int old = columnWidth.get(j) != null ? (int) columnWidth.get(j) : 0;
            if (width > old) {
              columnWidth.put(j, width);
              sheet.setColumnWidth(j, width < 3000 ? 3000 : width < 255 * 256 ? width : 60000);
            }
          }
          if (cellStringValue.contains("\n")) {
            cell.setCellStyle(wrapStyle);
            int newH = StringUtils.countMatches(cellStringValue, "\n") + 1;
            if (height < newH) {
              height = newH;
            }
          }
        }
        if (height != 1) {
          row.setHeightInPoints(height * 20);
        }
      }
    }
    return wb;
  }

  /**
   * excel導出
   *
   * @param fileNamePath 導出的文件名稱
   * @param sheetName 導出的sheet名稱
   * @param titles 第一行表頭
   * @param contents 數據集合
   */
  public static <T> File export(String fileNamePath, String sheetName, List<String> titles,
      List<List> contents)
      throws Exception {

    SXSSFWorkbook wb = createWorkBook(sheetName, titles, contents);
    File file = null;
    OutputStream os = null;
    file = new File(fileNamePath);
    try {
      os = new FileOutputStream(file);
      wb.write(os);
    } catch (Exception e) {
      throw new Exception("write excel file error!", e);
    } finally {
      if (null != os) {
        os.flush();
        os.close();
      }
    }
    return file;
  }

  public static void export(Workbook wb, String fileName, List<String> titles,
       HttpServletResponse response) throws Exception {
    try {
      if(!CollectionUtils.isEmpty(titles)){
        wb = appendTitles(wb, titles);
      }
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      wb.write(baos);
      baos.flush();
      byte[] aa = baos.toByteArray();
      response.addHeader("Content-Disposition",
          "attachment;filename*=utf-8'zh_cn'" + fileName);
      response.setHeader("Content-Type", "application/vnd.ms-excel");
      response.setCharacterEncoding("UTF-8");
      response.getOutputStream().write(aa);
      response.setContentLength(aa.length);
    } catch (Exception e) {
      e.printStackTrace();
      throw new Exception("write excel to stream error!", e);
    } finally {
      if (response.getOutputStream() != null) {
        response.getOutputStream().flush();
      }
    }
  }

  private static Workbook appendTitles(Workbook wb, List<String> titles) throws Exception {

    Sheet sheet = wb.getSheetAt(0);
    // 設置表頭的說明
    Row topRow = sheet.getRow(1);
    for (int i = 0; i < titles.size(); i++) {
      Cell cell = topRow.createCell(i + 6);
      cell.setCellType(HSSFCell.CELL_TYPE_NUMERIC);
      cell.setCellValue(titles.get(i));
      sheet.setColumnWidth( i + 6, titles.get(i).getBytes().length * 258);
    }
    return wb;
  }

  private static void setCellGBKValue(SXSSFCell cell, String value) {
    cell.setCellType(HSSFCell.CELL_TYPE_STRING);
    cell.setCellValue(value);
  }

  private static void setCellGBKValue(SXSSFCell cell, double value) {
    cell.setCellType(HSSFCell.CELL_TYPE_NUMERIC);
    cell.setCellValue(value);
  }

}

6. 在Service中寫下載文件的邏輯方法

public void downloadSample(HttpServletResponse response) {
    byte[] fileSource = projectConfiguration.fileBytes;
//防止對原數據進行操作
    byte[] fileBytes = Arrays.copyOf(fileSource, fileSource.length);
    //下載模板
    try {
      Workbook wb = WorkbookFactory.create(new ByteArrayInputStream(fileBytes));
      List<String> titleList = new ArrayList();
      titleList.add("興趣愛好");
      ExcelUtils.export(wb, projectConfiguration.fileName, titleList, response);
    } catch (Exception e) {
      log.info("下載模板出現問題");
      e.printStackTrace();
    }
  }