的OutOfMemoryError：Java堆

Question

public class seventhma { 

    XSSFSheet m_sheet; 
    int m_iNbRows; 
    int m_iCurrentRow = 0; 
    private static final String JAVA_TOSTRING = "EEE MMM dd HH:mm:ss zzz yyyy"; 

    public seventhma(XSSFSheet sheet) { 
     m_sheet = sheet; 
     m_iNbRows = sheet.getPhysicalNumberOfRows(); 
    } 

    /* 
    * Returns the contents of an Excel row in the form of a String array. 
    * 
    * @see com.ibm.ccd.common.parsing.Parser#splitLine() 
    */ 
    public String[] splitLine() throws Exception { 
     // if (m_iCurrentRow == m_iNbRows) 
     // return null; 

     XSSFRow row = m_sheet.getRow(m_iCurrentRow); 
     if (row == null) { 
      return null; 
     } else { 
      int cellIndex = 0; 
      int noOfCells = row.getPhysicalNumberOfCells(); 
      String[] values = new String[noOfCells]; 
      short firstCellNum = row.getFirstCellNum(); 
      short lastCellNum = row.getLastCellNum(); 

      if (firstCellNum >= 0 && lastCellNum >= 0) { 
       for (short iCurrent = firstCellNum; iCurrent < lastCellNum; iCurrent++) { 
        XSSFCell cell = (XSSFCell) row.getCell(iCurrent); 
        if (cell == null) { 
         values[iCurrent] = ""; 
         cellIndex++; 
         continue; 
        } else { 
         switch (cell.getCellType()) { 
          case XSSFCell.CELL_TYPE_NUMERIC: 
           double value = cell.getNumericCellValue(); 
           if (DateUtil.isCellDateFormatted(cell)) 

           { 
            if (DateUtil.isValidExcelDate(value)) { 
             Date date = DateUtil.getJavaDate(value); 
             SimpleDateFormat dateFormat = new SimpleDateFormat(JAVA_TOSTRING); 
             values[iCurrent] = dateFormat.format(date); 
            } else { 
             // throw new 
             // Exception("Invalid Date value found at row number " 
             // + 
             // row.getRowNum()+" and column number "+cell.getCellNum()); 
            } 
           } else { 
            values[iCurrent] = value + ""; 
           } 
           break; 

          case XSSFCell.CELL_TYPE_STRING: 
           values[iCurrent] = cell.getStringCellValue(); 
           break; 

          case XSSFCell.CELL_TYPE_BLANK: 
           values[iCurrent] = null; 
           break; 

          default: 
           values[iCurrent] = null; 
         } 
        } 
       } 
      } 
      m_iCurrentRow++; 
      return values; 
     } 

    } 

    public static void main(String args[]) { 
     XSSFWorkbook workBook = null; 
     File file = new File("E:\\Local\\Local2.xlsx"); 
     InputStream excelDocumentStream = null; 
     try { 
      excelDocumentStream = new FileInputStream(file); 
      // POIFSFileSystem fsPOI = new POIFSFileSystem(new 
      // BufferedInputStream(excelDocumentStream)); 
      BufferedInputStream bfs = new BufferedInputStream(excelDocumentStream); 
      workBook = new XSSFWorkbook(bfs); 
      seventhma parser = new seventhma(workBook.getSheetAt(0)); 
      String[] res = null; 
      while ((res = parser.splitLine()) != null) { 
       for (int i = 0; i < res.length; i++) { 
        System.out.println("[" + res[i] + "]" + "\t"); 

       } 
       System.out.println(res.length); 

      } 
      bfs = null; 
      excelDocumentStream.close(); 

     } catch (Exception e) { 
      System.out.println(e); 
      e.printStackTrace(); 
     } 

    } 
} 

這個節目給Java堆的空間不足和當含有列excel工作表被上傳它給ArrayIndexOutOfBoundException。
我已經增加了日食記憶至-Xmx1600m，但這也沒有奏效。

Answer 1

由於使用row.getPhysicalNumberOfCells()來確定其大小，因此您在values陣列上得到ArrayIndexOutOfBoundException。但row.getPhysicalNumberOfCells()只會計算文件中實際填充的單元格。

例如，如果你創建一個Excel工作表，並填寫僅列A，C和F，不碰其他細胞的功能row.getPhysicalNumberOfCells()將返回3
但你通過得到row.getFirstCellNum()遍歷所有的細胞和row.getLastCellNum()。因此，values[iCurrent]肯定會在您到達單元格F後出界。

關於OutOfMemory問題： XSSF使用大量內存。嘗試將虛擬機推到儘可能多的內存中，或者，如果您只是閱讀文件，請嘗試使用eventmodel API而不是usermodel（請考慮SAX與DOM）。