The maximum number of cell styles was exceeded. You can define up to 4000 styles

POI操作Excel中，导出的数据不是很大时，则不会有问题，而数据很多或者比较多时，

就会报以下的错误，是由于cell styles太多create造成，故一般可以把cellstyle设置放到循环外面

报错如下：

Caused by: java.lang.IllegalStateException: The maximum number of cell styles was exceeded. You can define up to 4000 styles in a .xls workbook
at org.apache.poi.hssf.usermodel.HSSFWorkbook.createCellStyle(HSSFWorkbook.java:1144)
at org.apache.poi.hssf.usermodel.HSSFWorkbook.createCellStyle(HSSFWorkbook.java:88)
at com.trendmicro.util.toExcel.ExcelExporter.addWorkbook(ExcelExporter.java:612)
at com.trendmicro.util.toExcel.ExcelExporter.exportToExcel(ExcelExporter.java:112)
at com.trendmicro.util.toExcel.ReportExporter.exportAutomationReport(ReportExporter.java:190)
at com.trendmicro.view.reports.TestCaseAutomationBean.exportAutoReport(TestCaseAutomationBean.java:856)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.el.parser.AstValue.invoke(AstValue.java:191)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
at org.apache.jasper.el.JspMethodExpression.invoke(JspMethodExpression.java:68)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
... 33 more

-------------示例--------------

错误示例

for (int i = 0; i < 10000; i++) {
    Row row = sheet.createRow(i);
    Cell cell = row.createCell((short) 0);
    CellStyle style = workbook.createCellStyle();
    Font font = workbook.createFont();
    font.setBoldweight(Font.BOLDWEIGHT_BOLD);
    style.setFont(font);
    cell.setCellStyle(style);
}

改正后正确代码

CellStyle style = workbook.createCellStyle();
Font font = workbook.createFont();
font.setBoldweight(Font.BOLDWEIGHT_BOLD);
style.setFont(font);
for (int i = 0; i < 10000; i++) {
    Row row = sheet.createRow(i);
    Cell cell = row.createCell((short) 0);
    cell.setCellStyle(style);
}

以上方法原地址：http://blog.csdn.net/hoking_in/article/details/7919530

方法二(不推荐，影响性能)：

1.4000最大样式错误

java.lang.IllegalStateException: The maximum number of cell styles was exceeded. You can define up to 4000 styles in a .xls workbook错误

找到zpoi.jar中org.zkoss.poi.hssf.usermodel.HSSFWorkbook修改createCellStyle函数内的最大样式数量即可。重新打zpoi.jar即可。

public HSSFCellStyle createCellStyle()
{
    if(workbook.getNumExFormats() == MAX_STYLES) {
        throw new IllegalStateException("The maximum number of cell styles was exceeded. " +
                "You can define up to 4000 styles in a .xls workbook");
    }
    ExtendedFormatRecord xfr = workbook.createCellXF();
    short index = (short) (getNumCellStyles() - 1);
    HSSFCellStyle style = new HSSFCellStyle(index, xfr, this);
    workbook.createCellXFExt(index);
    return style;
}

IE兼容问题

如果IE系列的浏览器出现了兼容问题（具体就是显示不出报表来），我已知的可能出现的问题有，Excel模板里有数字已字符串形式写入，或者是写日期格式的单元格出现了写入错误。具体的解决如下。

数字形式写入代码

public static Cell writeNumericValue(Sheet sheet, int row, int column,
        Double value) {
    Row poiRow = sheet.getRow(row);
    if (poiRow == null) {
        poiRow = sheet.createRow(row);
    }
    Cell poiCell = poiRow.getCell(column);

    if (poiCell != null) {
        poiRow.removeCell(poiCell);
    }
    poiCell = poiRow.createCell(column);
    poiCell.setCellType(Cell.CELL_TYPE_NUMERIC);
    poiCell.setCellValue(value);
    return poiCell;
}

写入日期代码

public static Cell writeDateValue(Workbook book, Sheet sheet, int row,
        int column, Date value) {
    Row poiRow = sheet.getRow(row);
    CreationHelper createHelper = book.getCreationHelper();
    if (poiRow == null) {
        poiRow = sheet.createRow(row);
    }
    Cell poiCell = poiRow.getCell(column);

    if (poiCell == null) {
        poiCell = poiRow.createCell(column);
    }

    CellStyle cellStyle = book.createCellStyle();
    cellStyle.setDataFormat(createHelper.createDataFormat().getFormat(
            "yyyy-mm-dd"));
    if (value != null) {
        poiCell.setCellValue(value);
    } else {
        poiCell.setCellValue(new Date());
    }
    poiCell.setCellStyle(cellStyle);

    return poiCell;
}

 以上方法原地址：http://realgodo.iteye.com/blog/1105529