我如何讀取excel文件並將值設置爲空

Question

我想讀取excel文件，如果有任何數據，我想將其設置爲null，然後開始寫入。這是我將Excel表單數據設置爲null的原因。我能夠寫入成功，但在寫之前，我想將值設置爲null。

FileOutputStream out = null; 

try{ 
      FileInputStream file = new FileInputStream(new File("/test.xls")); 
      HSSFWorkbook oldFile = new HSSFWorkbook(file); 
      HSSFSheet sheet = oldFile.getSheetAt(0); 
      file.close(); 

      oldFile.write(null); 
      outFile.close(); 

     } catch(Exception e){ 
      e.printStackTrace(); 
     } 

Answer 1

一個簡單的解決方法是刪除並創建一個sheet：

File destFile = new File("/test.xls"); 
FileInputStream fileStream = new FileInputStream(destFile); 
POIFSFileSystem fsPoi = new POIFSFileSystem(fileStream); 

HSSFWorkbook workbook = new HSSFWorkbook(fsPoi); 

int index = 0; 

HSSFSheet sheet = workbook.getSheet("Setup"); 
if(sheet != null) { 
    index = workbook.getSheetIndex(sheet); 
    workbook.removeSheetAt(index); 
} 
workbook.createSheet("Setup"); 
FileOutputStream output = new FileOutputStream(destFile); 
workbook.write(output); 
output.close();