java - 避免 Excel 中的文件内容被覆盖

Question

我只想有一个 FileOutputStream 将工作簿的内容写入应用程序中的文件，并在此 Excel 中创建多个工作表。我正在使用 Apache POI 读取/写入我的 Excel。我有以下方法来执行此操作 -

private static void writeToSpreadSheet(String test,Map<String,String> errorMap,Object object) throws IOException {
    HSSFWorkbook workbook = new HSSFWorkbook()
    HSSFSheet sheet = workbook.createSheet(test);
    FileOutputStream fis = new FileOutputStream("output/test.xls");
    //do stuff and finally write workbook contents to a file
    workbook.write(fis);
    if (fis != null)
        fis.close();
}

我在这里面临的问题是，每次调用writeToSpreadSheet时，都会创建一个新文件，并且现有数据会被覆盖。我只想要一个文件，并且需要将新工作表添加到我现有的文件中。我如何实现这一目标？

Answer 1

我不在我的机器附近，所以我无法为您提供确切的代码库，但如果您按照确切的步骤操作，那么您可以获得所需的结果。

我已经从这里和那里组装了代码，它不会按原样工作。您必须修改代码并使其按照您想要的方式工作。我把这部分留给你。

final File file = "/output/test.xls";
HSSFWorkbook workbook = null;
FileOutputStream fileOut = new FileOutputStream(file);

private static void writeToSpreadSheet(String test,
        Map<String, String> errorMap, Object object) throws IOException {
    // Check whether your file exist
    // if not then crate a workbook
    // something like below

    if (!file.exists()) {
        System.out.println("Creating a new workbook '" + file + "'");
        workbook = new HSSFWorkbook();
    } else {
        // create a method to get very last sheet number something like
        // following .
        int sheetIndex = getLastSheetIndex();
        // if you dont to go with find last sheet index idea then you can
        // create your unique name may be like timestamp or so
        // add the new sheet with new index
        HSSFSheet sheet = workbook.createSheet("Test Sheet " + sheetIndex);
        // Write your content
        workbook.write(fileOut);
        fileOut.close();
    }

}

private static int getLastSheetIndex() {
    int sheetIndex = 1;
    while (workbook.getSheet("Test Sheet " + sheetIndex) != null) {
        sheetIndex++;
    }
    return sheetIndex;
}

目前你在做什么:

private static void writeToSpreadSheet(String test,
        Map<String, String> errorMap, Object object) throws IOException {
    // Creating the new workbook every time you call this method
    HSSFWorkbook workbook = new HSSFWorkbook();

    // Adding the same sheet to newly created workbook
    HSSFSheet sheet = workbook.createSheet(test);
    FileOutputStream fis = new FileOutputStream("output/test.xls");
    // causing to overwrite your old workbook
    workbook.write(fis);
    if (fis != null)
        fis.close();
}