使用POI创建Excel工作簿时有哪些(陷阱和)限制？

Question

刚看到崩溃,我们超过了255列.也许这个问题应该直接转向POI,但是我可以说我不想打扰他们,以便进一步开发它已经具有的增长性有用的API.;-) 限制页面不会逐步详细说明.

那么:假设输出在Excel中可读,您对实际限制的体验是什么？有没有人使用POI来评估和探索POI生成的Excel文件的软硬限制？

我可以在POI界面中快速找到的唯一限制如下.Microsoft列出了Excel 中的其他限制,这些限制似乎没有在POI中涵盖.

编辑:哎呀.刚刚意识到我们在过去的5年里没有更新过POI,所以下面的代码可能已经被替换了100次.

编辑:以下代码自2008年10月19日版本3.2以来没有变化.

/**
 * @throws RuntimeException if the bounds are exceeded.
 */
private void checkBounds(int cellNum) {
  if (cellNum > 255) {
      throw new RuntimeException("You cannot have more than 255 columns "+
                "in a given row (IV).  Because Excel can't handle it");
  }
  else if (cellNum < 0) {
      throw new RuntimeException("You cannot reference columns with an index of less then 0.");
  }
}

Answer 1

Marliese,我对poi框架中的这个错误感到恼火,并且理解我需要一个styleManager.这些帖子让我觉得所有工作都已完成,直到我得出与你相同的结论.我不想重新发明轮子,所以我下载了他的框架的源代码并搜索了CellStyleManager.setCellStyle()的用法.事实是,在代码中,创建了两个初始HSSFCellStyle对象,defaultCellStyle和cellStyle.任何时候自定义样式使用cellStyle,然后使用CellStyleManager设置它.如果样式存在,则重用它,如果不存在,则创建它.任何其他尝试自定义另一种样式的尝试都是从使用CellStyleHelper的函数和defaultCellStyle重置cellStyle开始,该函数不受所有程序的影响.所以最终你会得到两个超出实际需要的样式,但到目前为止比使用另一个api更好.

正如paulgreg所说,代码遍布整个框架,但我加入所有代码只需要两个类.我把它们留在这里,直到我写信给paulgreg和poi开发团队将它合并到它的jar中,因为我认为对于在excel中写入的未知数据,你需要这种经理.

更改基本上是,管理器知道工作簿,提供样式对象,并实现CellStyleHelper的代码.(它们不太通用,因为管理器需要知道工作簿,总的来说,因为你必须只使用一次getGeneralStyle调用(因为它是在任何调用中重置的同一个对象,但是一般用途是代码适合)所以使用它:

... Creates a workbook
CellStyleManager styleManager = new CellStyleManager(workbook);
... Create a cell
HSSFCellStyle style = styleManager.getGeneralStyle();
styleManager.setCellStyle(cell, style); // no more 4000 styles error!

代码:谢谢PaulGreg!

// CellStyleCacheManager.java

public class CellStyleCacheManager {
    protected Set cellStyles;
    protected HSSFCellStyle cellStyle;
    protected HSSFCellStyle defaultValuesCellStyle;
    protected HSSFWorkbook workbook;

    public CellStyleCacheManager(HSSFWorkbook workbook) {
        this.workbook = workbook;
        this.cellStyles = new HashSet();
        // El desperdicio de estilos será pués de dos
        cellStyle = workbook.createCellStyle();
        // Estilo almacenado para reiniciar el que se va a usar
        defaultValuesCellStyle = workbook.createCellStyle();
    }

    /** Si el estilo se crea con createCellStyle, ya no podremos hacer nada */
    public void setCellStyle(HSSFCell cell, HSSFCellStyle cellStyle) {
        CellStyleWrapper cellStyleWrp = new CellStyleWrapper(cellStyle);
        CellStyleWrapper cachedCellStyleWrp = null;

        Iterator it = cellStyles.iterator();

        while(it.hasNext() && (cachedCellStyleWrp == null)) {
            CellStyleWrapper tmpCachedCellStyleWrp = (CellStyleWrapper) it.next();

            if(tmpCachedCellStyleWrp.equals(cellStyleWrp)) {
                // Si algún estilo coincide con el actual usamos ese
                cachedCellStyleWrp = tmpCachedCellStyleWrp;
            }
        }

        if(cachedCellStyleWrp == null) {
            // Si el estilo no existe creamos uno nuevo
            HSSFCellStyle newCellStyle = workbook.createCellStyle();
            CellStyleCacheManager.copyCellStyle(workbook, cellStyle, newCellStyle);

            CellStyleWrapper newWrp = new CellStyleWrapper(newCellStyle);
            cellStyles.add(newWrp);
            cachedCellStyleWrp = newWrp;
        }

        cell.setCellStyle(cachedCellStyleWrp.getHSSFCellStyle());
    }

    public HSSFCellStyle getGeneralStyle() {
        copyCellStyle(workbook, cellStyle, defaultValuesCellStyle);
        return cellStyle;
    }

    public static void copyCellStyle(HSSFWorkbook wb, HSSFCellStyle c1, HSSFCellStyle c2) {
        c2.setAlignment(c1.getAlignment());
        c2.setBorderBottom(c1.getBorderBottom());
        c2.setBorderLeft(c1.getBorderLeft());
        c2.setBorderRight(c1.getBorderRight());
        c2.setBorderTop(c1.getBorderTop());
        c2.setBottomBorderColor(c1.getBottomBorderColor());
        c2.setDataFormat(c1.getDataFormat());
        c2.setFillBackgroundColor(c1.getFillBackgroundColor());
        c2.setFillForegroundColor(c1.getFillForegroundColor());
        c2.setFillPattern(c1.getFillPattern());

        try {
            c2.setFont(wb.getFontAt(c1.getFontIndex()));
        } catch(NullPointerException e) {
            TLogger.getInstance().log(e.getMessage());
        } catch(ArrayIndexOutOfBoundsException e) {
            TLogger.getInstance().log("Be sure to have intialized all POI font objects !\n%s",e.getMessage());
        }

        c2.setHidden(c1.getHidden());
        c2.setIndention(c1.getIndention());
        c2.setLeftBorderColor(c1.getLeftBorderColor());
        c2.setLocked(c1.getLocked());
        c2.setRightBorderColor(c1.getRightBorderColor());
        c2.setRotation(c1.getRotation());
        c2.setTopBorderColor(c1.getTopBorderColor());
        c2.setVerticalAlignment(c1.getVerticalAlignment());
        c2.setWrapText(c1.getWrapText());
    }   
}

CellStyleWrapper.java

public class CellStyleWrapper implements Comparable {
    private HSSFCellStyle cs;
    private int hashCode;

    public CellStyleWrapper(HSSFCellStyle cs) {
        this.cs = cs;
    }

    public boolean equals(Object obj) {
        CellStyleWrapper csWrp_;
        HSSFCellStyle cs_;

        try {
            csWrp_ = (CellStyleWrapper) obj;
        } catch(ClassCastException e) {
            return false;
        }

        cs_ = csWrp_.getHSSFCellStyle();

        return (cs.getAlignment() == cs_.getAlignment()) && (cs.getBorderBottom() == cs_.getBorderBottom())
                && (cs.getBorderLeft() == cs_.getBorderLeft()) && (cs.getBorderRight() == cs_.getBorderRight())
                && (cs.getBorderTop() == cs_.getBorderTop())
                && (cs.getBottomBorderColor() == cs_.getBottomBorderColor())
                && (cs.getDataFormat() == cs_.getDataFormat())
                && (cs.getFillBackgroundColor() == cs_.getFillBackgroundColor())
                && (cs.getFillForegroundColor() == cs_.getFillForegroundColor())
                && (cs.getFillPattern() == cs_.getFillPattern()) && (cs.getFontIndex() == cs_.getFontIndex())
                && (cs.getHidden() == cs_.getHidden()) && (cs.getIndention() == cs_.getIndention())
                && (cs.getLeftBorderColor() == cs_.getLeftBorderColor()) && (cs.getLocked() == cs_.getLocked())
                && (cs.getRightBorderColor() == cs_.getRightBorderColor()) && (cs.getRotation() == cs_.getRotation())
                && (cs.getTopBorderColor() == cs_.getTopBorderColor())
                && (cs.getVerticalAlignment() == cs_.getVerticalAlignment())
                && (cs.getWrapText() == cs_.getWrapText());
    }

    private int v(int i) {
        if(i == 0) {
            return 1;
        } else {
            return i;
        }
    }

    public int hashCode() {
        if(hashCode == 0) {
            hashCode = 17;
            hashCode = 37 * v(cs.getBorderBottom());
            hashCode = 37 * v(cs.getBorderLeft());
            hashCode = 37 * v(cs.getBorderRight());
            hashCode = 37 * v(cs.getBorderTop());
            hashCode = 37 * v(cs.getBottomBorderColor());
            hashCode = 37 * v(cs.getDataFormat());
            hashCode = 37 * v(cs.getFillBackgroundColor());
            hashCode = 37 * v(cs.getFillForegroundColor());
            hashCode = 37 * v(cs.getFillPattern());
            hashCode = 37 * v(cs.getFontIndex());
            hashCode = 37 * (cs.getHidden() ? 1 : (-1));
            hashCode = 37 * v(cs.getIndention());
            hashCode = 37 * v(cs.getLeftBorderColor());
            hashCode = 37 * (cs.getLocked() ? 1 : (-1));
            hashCode = 37 * v(cs.getRightBorderColor());
            hashCode = 37 * v(cs.getRotation());
            hashCode = 37 * v(cs.getTopBorderColor());
            hashCode = 37 * v(cs.getVerticalAlignment());
            hashCode = 37 * (cs.getWrapText() ? 1 : (-1));
        }

        return hashCode;
    }

    public int compareTo(Object obj) {
        int diff = 0;
        CellStyleWrapper csWrp_;
        HSSFCellStyle cs_;

        try {
            csWrp_ = (CellStyleWrapper) obj;
        } catch(ClassCastException e) {
            return -1;
        }

        cs_ = csWrp_.getHSSFCellStyle();

        diff = cs.getAlignment() - cs_.getAlignment();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getBorderBottom() - cs_.getBorderBottom();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getBorderLeft() - cs_.getBorderLeft();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getBorderRight() - cs_.getBorderRight();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getBorderTop() - cs_.getBorderTop();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getBottomBorderColor() - cs_.getBottomBorderColor();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getDataFormat() - cs_.getDataFormat();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getFillBackgroundColor() - cs_.getFillBackgroundColor();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getFillForegroundColor() - cs_.getFillForegroundColor();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getFillPattern() - cs_.getFillPattern();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getFontIndex() - cs_.getFontIndex();

        if(diff != 0) {
            return diff;
        }

        if(cs.getHidden() != cs_.getHidden()) {
            return -1;
        }

        diff = cs.getIndention() - cs_.getIndention();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getLeftBorderColor() - cs_.getLeftBorderColor();

        if(diff != 0) {
            return diff;
        }

        if(cs.getLocked() != cs_.getLocked()) {
            return -1;
        }

        diff = cs.getRightBorderColor() - cs_.getRightBorderColor();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getRotation() - cs_.getRotation();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getTopBorderColor() - cs_.getTopBorderColor();

        if(diff != 0) {
            return diff;
        }

        diff = cs.getVerticalAlignment() - cs_.getVerticalAlignment();

        if(diff != 0) {
            return diff;
        }

        if(cs.getWrapText() != cs_.getWrapText()) {
            return -1;
        }

        return 0;
    }

    public HSSFCellStyle getHSSFCellStyle() {
        return cs;
    }
}

有趣的是,在poi源中,在HSSFCellStyle的评论中,这个条目来了

// Why would you do that??
protected HSSFCellStyle(...

4000种风格限制男人,这是否足够的原因？