更新Java Apache POI中的现有Excel文件

我正在尝试编写一个每天运行的Java程序（使用任务计划程序），并在每次运行时将一列添加到Excel电子表格中。 我遇到的问题是它只是重新写入文件，而不是附加到它。 我正在使用Apache POI，这里是相关的代码：

public static void toExcel(List<String> results, List<Integer> notActive)throws IOException{ try { FileInputStream fIPS= new FileInputStream("test.xls"); //Read the spreadsheet that needs to be updated HSSFWorkbook wb; HSSFSheet worksheet; if(fIPS.available()>=512) { wb = new HSSFWorkbook(fIPS); //If there is already data in a workbook worksheet = wb.getSheetAt(0); }else{ wb = new HSSFWorkbook(); //if the workbook was just created worksheet = wb.createSheet("Data"); } //Access the worksheet, so that we can update / modify it HSSFRow row1 = worksheet.createRow(0); //0 = row number int i=0; Cell c = row1.getCell(i); while (!(c == null || c.getCellType() == Cell.CELL_TYPE_BLANK)) { //cell is empty i++; c=row1.getCell(i); } HSSFRow rowx; int x=0; for(String s : results) { rowx = worksheet.createRow(x); HSSFCell cellx = rowx.createCell(i); //0 = column number cellx.setCellValue(s); x++; } fIPS.close(); //Close the InputStream FileOutputStream output_file =new FileOutputStream("test.xls");//Open FileOutputStream to write updates wb.write(output_file); //write changes output_file.close(); //close the stream } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } 

Answer 1

我想你是一次又一次地创build新的行和单元格，导致重写excel。

本质上你需要获取行和单元格，而不是在程序中创build它们。

 HSSFRow row1 = worksheet.createRow(0); 

您可能需要获取行而不是创build它。

 HSSFRow row1 = worksheet.getRow(0); 

https://poi.apache.org/apidocs/org/apache/poi/ss/usermodel/Sheet.html#getRow(int）

这个小例子更新第二行的第二个单元格：

 //Read the spreadsheet that needs to be updated FileInputStream fsIP= new FileInputStream(new File("C:\\Excel.xls")); //Access the workbook HSSFWorkbook wb = new HSSFWorkbook(fsIP); //Access the worksheet, so that we can update / modify it. HSSFSheet worksheet = wb.getSheetAt(0); // declare a Cell object Cell cell = null; // Access the second cell in second row to update the value cell = worksheet.getRow(1).getCell(1); // Get current cell value value and overwrite the value cell.setCellValue("OverRide existing value"); //Close the InputStream fsIP.close(); //Open FileOutputStream to write updates FileOutputStream output_file =new FileOutputStream(new File("C:\\Excel.xls")); //write changes wb.write(output_file); //close the stream output_file.close();