poi解析excel（含有公式）

 /**
  * Jun 25, 2012
  */

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;

 import org.apache.commons.io.FilenameUtils;
 import org.apache.poi.hssf.usermodel.HSSFWorkbook;
 import org.apache.poi.ss.usermodel.*;
 import org.apache.poi.xssf.usermodel.XSSFWorkbook;

 /**
  * Excel组件
  *
  * @author Snowolf
  * @version 1.0
  * @since 1.0
  */
 public abstract class ExcelHelper {

     /**
      * Excel 2003
      */
     private final static String XLS = "xls";
     /**
      * Excel 2007
      */
     private final static String XLSX = "xlsx";
     /**
      * 分隔符
      */
     private final static String SEPARATOR = "|";

     /**
      * 由Excel文件的Sheet导出至List
      *
      * @param file
      * @param sheetNum
      * @return
      */
     public static List<String> exportListFromExcel(File file, int sheetNum)
             throws IOException {
         return exportListFromExcel(new FileInputStream(file),
                 FilenameUtils.getExtension(file.getName()), sheetNum);
     }

     /**
      * 由Excel流的Sheet导出至List
      *
      * @param is
      * @param extensionName
      * @param sheetNum
      * @return
      * @throws IOException
      */
     public static List<String> exportListFromExcel(InputStream is,
                                                    String extensionName, int sheetNum) throws IOException {

         Workbook workbook = null;

         if (extensionName.toLowerCase().equals(XLS)) {
             workbook = new HSSFWorkbook(is);
         } else if (extensionName.toLowerCase().equals(XLSX)) {
             workbook = new XSSFWorkbook(is);
         }

         return exportListFromExcel(workbook, sheetNum);
     }

     /**
      * 由指定的Sheet导出至List
      *
      * @param workbook
      * @param sheetNum
      * @return
      * @throws IOException
      */
     private static List<String> exportListFromExcel(Workbook workbook,
                                                     int sheetNum) {

         Sheet sheet = workbook.getSheetAt(sheetNum);

         // 解析公式结果
         FormulaEvaluator evaluator = workbook.getCreationHelper()
                 .createFormulaEvaluator();

         List<String> list = new ArrayList<String>();

         int minRowIx = sheet.getFirstRowNum();
         int maxRowIx = sheet.getLastRowNum();
         for (int rowIx = minRowIx; rowIx <= maxRowIx; rowIx++) {
             Row row = sheet.getRow(rowIx);
             StringBuilder sb = new StringBuilder();

             short minColIx = row.getFirstCellNum();
             short maxColIx = row.getLastCellNum();
             for (short colIx = minColIx; colIx <= maxColIx; colIx++) {
                 Cell cell = row.getCell(new Integer(colIx));
                 CellValue cellValue = evaluator.evaluate(cell);
                 if (cellValue == null) {
                     continue;
                 }
                 // 经过公式解析，最后只存在Boolean、Numeric和String三种数据类型，此外就是Error了
                 // 其余数据类型，根据官方文档，完全可以忽略http://poi.apache.org/spreadsheet/eval.html
                 switch (cellValue.getCellTypeEnum()) {
                     case BOOLEAN:
                         sb.append(SEPARATOR + cellValue.getBooleanValue());
                         break;
                     case NUMERIC:
                         // 这里的日期类型会被转换为数字类型，需要判别后区分处理
                         if (DateUtil.isCellDateFormatted(cell)) {
                             sb.append(SEPARATOR + cell.getDateCellValue());
                         } else {
                             sb.append(SEPARATOR + cellValue.getNumberValue());
                         }
                         break;
                     case STRING:
                         sb.append(SEPARATOR + cellValue.getStringValue());
                         break;
                     case FORMULA:
                         break;
                     case BLANK:
                         break;
                     case ERROR:
                         break;
                     default:
                         break;
                 }
             }
             list.add(sb.toString());
         }
         return list;
     }
 }

由于Excel中的数据有日期、公式等等格式，参考http://poi.apache.org/spreadsheet/eval.html做了修改，完全兼容。

当前的Excel，C列是根据A、B相乘计算而来，D列是日期格式： 

测试：

 /**
  * Jun 25, 2012
  */

 import java.io.File;
 import java.io.IOException;
 import java.util.List;

 import static org.junit.Assert.*;
 import org.junit.Test;

 /**
  *
  * @author Snowolf
  * @version 1.0
  * @since 1.0
  */
 public class ExcelHelperTest {

     @Test
     public void test() {
         String path = "d://MavenProject//usingGit//src//main//java//excel.xlsx";
         List<String> list = null;
         try {
             list = ExcelHelper.exportListFromExcel(new File(path), 0);
             assertNotNull(list);
         } catch (IOException e) {
             fail();
         }

     }
 }

结果：

参考https://snowolf.iteye.com/blog/1569252