使用Apache POI操作Excel文件---在已有的Excel文件中插入一行新的数据

package org.test;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;  

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;  

public class PoiTesst {
    //当前文件已经存在
    private String excelPath = "F:\\123abcdefg.xlsx";
    //从第几行插入进去
    private int insertStartPointer = 3;
    //在当前工作薄的那个工作表单  （sheet页名称）
    private String sheetName = "sheet1";  

    /**
     * 总的入口方法
     */
    public static void main(String[] args) {
        PoiTesst crt = new PoiTesst();
        crt.insertRows();
    }  

    /**
     * 在已有的Excel文件中插入一行新的数据的入口方法
     */
    public void insertRows() {
        XSSFWorkbook wb = returnWorkBookGivenFileHandle();
        XSSFSheet sheet1 = wb.getSheet(sheetName);
        XSSFRow row = createRow(sheet1, insertStartPointer);
        createCell(row);
        saveExcel(wb);  

    } 

    /**
     * 找到需要插入的行数，并新建一个POI的row对象
     * @param sheet
     * @param rowIndex
     * @return
     */
     private XSSFRow createRow(XSSFSheet sheet, Integer rowIndex) {
         XSSFRow row = null;
         if (sheet.getRow(rowIndex) != null) {
             int lastRowNo = sheet.getLastRowNum();
             sheet.shiftRows(rowIndex, lastRowNo, 1);
         }
         row = sheet.createRow(rowIndex);
         return row;
     }  

     /**
      * 创建要出入的行中单元格
      * @param row
      * @return
      */
     private XSSFCell createCell(XSSFRow row) {
         XSSFCell cell = row.createCell((short) 0);
         cell.setCellValue(999999);
         row.createCell(1).setCellValue(1.2);
         row.createCell(2).setCellValue("This is a string cell");
         return cell;
     } 

    /**
     * 保存工作薄
     * @param wb
     */
    private void saveExcel(XSSFWorkbook wb) {
        FileOutputStream fileOut;
        try {
            fileOut = new FileOutputStream(excelPath);
            wb.write(fileOut);
            fileOut.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }  

    }  

   /**
    * 得到一个已有的工作薄的POI对象
    * @return
    */
    private XSSFWorkbook returnWorkBookGivenFileHandle() {
        XSSFWorkbook wb = null;
        FileInputStream fis = null;
        File f = new File(excelPath);
        try {
            if (f != null) {
                fis = new FileInputStream(f);
                wb = new XSSFWorkbook(fis);
            }
        } catch (Exception e) {
            return null;
        } finally {
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return wb;
    }  

}