使用Apache-poi将工作表添加到现有excel文件而无需重写完整文件

我正在研究Apache poi并尝试在现有的excel文件中添加新工作表 .

我正在使用FileOutputStream将工作表添加到工作簿对象并将工作簿对象写入文件 .

FileOutputStream outputStream = null;
    FileInputStream inputStream = null;
    HSSFWorkbook workbook = null;
    int nRows = 5000;
    int nCols = 100;
    try {
        ArrayList<String> names = new ArrayList();
        names.add("NewSheet1");
        names.add("NewSheet2");
        names.add("NewSheet3");
        names.add("NewSheet4");
        workbook = new HSSFWorkbook();
        for (String name : names) {
            HSSFSheet sheet = workbook.createSheet(name);
            for (int rowCounter = 0; rowCounter < nRows; rowCounter++) {
                HSSFRow row = sheet.createRow(rowCounter);
                for (int colCounter = 0; colCounter < nCols; colCounter++) {
                    HSSFCell cell = row.createCell(colCounter);
                    cell.setCellValue("" + rowCounter + colCounter);
                }
            }
        }
        outputStream = new FileOutputStream(excelFilePath);
        workbook.write(outputStream);

    } catch (Exception ex) {
        ex.printStackTrace();
    } finally {
        try {
            if (outputStream != null) {
                outputStream.flush();
                outputStream.close();
                outputStream = null;
            }
            if (workbook != null) {
                workbook = null;
            }
            if (inputStream != null) {
                inputStream.close();
                inputStream = null;
            }
        } catch (Exception e) {
            e.getMessage();
        }
    }

但它正在抛出内存异常 .

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2245)
at java.util.Arrays.copyOf(Arrays.java:2219)
at java.util.ArrayList.grow(ArrayList.java:242)
at java.util.ArrayList.ensureExplicitCapacity(ArrayList.java:216)
at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:208)
at java.util.ArrayList.add(ArrayList.java:440)
at org.apache.poi.hssf.usermodel.HSSFWorkbook$SheetRecordCollector.visitRecord(HSSFWorkbook.java:1200)
at org.apache.poi.hssf.record.aggregates.RecordAggregate$PositionTrackingVisitor.visitRecord(RecordAggregate.java:106)
at org.apache.poi.hssf.record.aggregates.RecordAggregate$PositionTrackingVisitor.visitRecord(RecordAggregate.java:106)
at org.apache.poi.hssf.record.aggregates.ValueRecordsAggregate.visitCellsForRow(ValueRecordsAggregate.java:254)
at org.apache.poi.hssf.record.aggregates.RowRecordsAggregate.visitContainedRecords(RowRecordsAggregate.java:269)
at org.apache.poi.hssf.model.Sheet.visitContainedRecords(Sheet.java:550)
at org.apache.poi.hssf.usermodel.HSSFWorkbook.getBytes(HSSFWorkbook.java:1247)
at org.apache.poi.hssf.usermodel.HSSFWorkbook.write(HSSFWorkbook.java:1157)
at com.ExcelTrial.main(ExcelTrial.java:43)

所以，我尝试了其他方法 .

我正在尝试逐页编写excel文件，即通过在每个工作表的输入模式下打开来更新文件 .

已在我的磁盘中创建Excel文件 .

我只是按照以下步骤操作：

• 使用FileInputStream在输入中打开文件

• 使用此FileInputStream对象创建工作簿

• 创建工作表，编写数据

• 使用FileOutputStream写入文件

String excelFilePath = "C:\\TrialNew\\TrialNew.xls";
FileOutputStream outputStream = null;
FileInputStream inputStream = null;
HSSFWorkbook workbook = null;
int nRows = 5000;
int nCols = 100;
try {
    ArrayList<String> names = new ArrayList();
    names.add("NewSheet1");
    names.add("NewSheet2");
    names.add("NewSheet3");
    names.add("NewSheet4");
    for (String name : names) {
        inputStream = new FileInputStream(new File(excelFilePath));
        workbook = new HSSFWorkbook(inputStream);
        HSSFSheet sheet = workbook.createSheet(name);
        for (int rowCounter = 0; rowCounter < nRows; rowCounter++) {
            HSSFRow row = sheet.createRow(rowCounter);
            for (int colCounter = 0; colCounter < nCols; colCounter++) {
                HSSFCell cell = row.createCell(colCounter);
                cell.setCellValue("" + rowCounter + colCounter);
            }
        }

        outputStream = new FileOutputStream(excelFilePath);

        workbook.write(outputStream);
        outputStream.flush();
        outputStream.close();
        outputStream = null;
        workbook = null;
        inputStream.close();
        inputStream = null;
    }

} catch (Exception ex) {
    ex.printStackTrace();
} finally {
    try {
        if (outputStream != null) {
            outputStream.flush();
            outputStream.close();
            outputStream = null;
        }
        if (workbook != null) {
            workbook = null;
        }
        if (inputStream != null) {
            inputStream.close();
            inputStream = null;
        }
    } catch (Exception e) {
        e.getMessage();
    }
}

它仍然提供相同的例外 . 但我注意到的一件事是，当我尝试将新工作表（例如“Newsheet2”）添加到已经包含“NewSheet1”的文件时，它正在重写整个工作簿，而不是在最后编写新工作表 .

有没有办法在最后写一个新的表，而不是一次又一次地重写所有的表？这可能会解决我的问题 .

或者，如果有任何其他解决方案来避免此Java堆空间异常，建议是最受欢迎的 .