无法将数据写入到Excel文件细胞

Question

我想写一个字符串到现有的Excel文件细胞，这里是我的方法：

public void setSuccessMessageInExcellFile(File uploadFile, HttpServletResponse response) { 


     try { 
      FileInputStream fileInputStream = new FileInputStream(uploadFile); 

      HSSFWorkbook workbook = new HSSFWorkbook(fileInputStream); 
      HSSFSheet excelSheet = workbook.getSheetAt(0); 
      HSSFCell cell = excelSheet.getRow(0).getCell(0); 
      cell.setCellValue("Imported"); 

      fileInputStream.close(); 
      FileOutputStream out = new FileOutputStream(uploadFile); 
      workbook.write(out); 
      out.close(); 
     } catch(Exception ex) { 
      ex.getCause().printStackTrace(); 
     } 

    } 

没有错误，但“进口”文字不可用在我的Excel文件中。

Answer 1

确保您的文件存在，可写且具有正确的Excel版本。之后，你应该改变你的代码一样，因为你得到一个NullPointerException否则：

public void setSuccessMessageInExcellFile(File uploadFile, HttpServletResponse response) { 


    try { 
     FileInputStream fileInputStream = new FileInputStream(uploadFile); 

     HSSFWorkbook workbook = new HSSFWorkbook(fileInputStream); 
     HSSFSheet excelSheet = workbook.getSheetAt(0); 
     HSSFCell cell = excelSheet.createRow(0).createCell(0); 
     cell.setCellValue("Imported"); 

     fileInputStream.close(); 
     FileOutputStream out = new FileOutputStream(uploadFile); 
     workbook.write(out); 
     out.close(); 
    } catch(Exception ex) { 
     ex.getCause().printStackTrace(); 
    } 
} 

，更好的将被把closables在尝试像这样的说法：

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