创建工作簿 Apache POI 的通用方式

Question

我有一个使用 Apache POI 库读取 excel 表的方法。为了使该方法通用，我需要在 catch 块中编写一些代码。方法如下：

private List<String[]> readFile(String filePath) throws IOException{
        List<String[]> sheetValues = new ArrayList<String[]>();
        //Two types of fileInputStreams for both the types of workbook i am about to use
        //
        FileInputStream fileInputStream = new FileInputStream(new File(filePath));
        FileInputStream fileInputStream2 = new FileInputStream(new File(filePath));
        LineItemFileReader fileReader = new LineItemFileReaderImpl();
        //If the file is in xls format i should use HSSFWorkbook
        //If the file is in xlsx format i should use XSSFWorkbook
        try {
        //If the file is in xlsx format then the below line will throw the
        //Exception and catch block code will be executed
            HSSFWorkbook workbook = new HSSFWorkbook(fileInputStream);
            FormulaEvaluator evaluator = workbook.getCreationHelper().createFormulaEvaluator();
            sheetValues = fileReader.ParseSheet(workbook.getSheetAt(1),evaluator);
        } catch (OfficeXmlFileException exception){
            XSSFWorkbook workbook = new XSSFWorkbook(fileInputStream2);
            FormulaEvaluator evaluator = workbook.getCreationHelper().createFormulaEvaluator();
            sheetValues = fileReader.ParseSheet(workbook.getSheetAt(1),evaluator);
        } finally{
            fileInputStream.close();
            fileInputStream2.close();
        }
        return sheetValues;
    }

所以这里发生的事情是我不知道我正在提供什么类型的文件。我是根据上面给出的 try/catch 块来决定的。那么是否有任何通用的方法来决定使用哪个工作簿？由于上述代码在 catch 块中编写了流控制逻辑，因此这是一种不好的做法。

Answer 1

使用WorkbookFactory.create(...) 打开Workbook。它将在内部创建适当的子类：

Workbook workbook = WorkbookFactory.create(new File(filePath));
// ...
workbook.close();