fix: fix error in using relativeHeadRowIndex for writing tables only

[32154678925]

Purpose of the pull request

Closed: #794
When you do not write directly in the sheet, but only write data in the table and set the head, the offset value set with relativeHeadRowIndex() will make an error, and the blank line with the specified offset will be empty again between the head and the data. If the head is not set, the offset value set with relativeHeadRowIndex() will not take effect

What's changed?

Change the judgment of whether to add offset in the add method in the ExcelWriteAddExecutor class from writeSheetHolder to currentWriteHolder

Before:

WriteSheetHolder writeSheetHolder = writeContext.writeSheetHolder();
int newRowIndex = writeSheetHolder.getNewRowIndexAndStartDoWrite();
if (writeSheetHolder.isNew()
        && !writeSheetHolder.getExcelWriteHeadProperty().hasHead()) {
    newRowIndex += writeContext.currentWriteHolder().relativeHeadRowIndex();
}

After:

WriteSheetHolder writeSheetHolder = writeContext.writeSheetHolder();
WriteHolder currentWriteHolder = writeContext.currentWriteHolder();
int newRowIndex = writeSheetHolder.getNewRowIndexAndStartDoWrite();
if (currentWriteHolder.isNew()) {
    AbstractWriteHolder writeHolder = (AbstractWriteHolder) currentWriteHolder;
    if(!writeHolder.getExcelWriteHeadProperty().hasHead()){
        newRowIndex += currentWriteHolder.relativeHeadRowIndex();
    }
}

Checklist

• I have read the Contributor Guide.
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

[Copilot]

Pull request overview

This pull request fixes a bug where relativeHeadRowIndex() was being applied twice when writing data to tables with headers, causing extra blank rows to appear between the header and data. The fix changes the condition from checking whether the sheet is new to checking whether the current write holder (which could be a table) is new and has no head.

Changes:

• Modified logic in ExcelWriteAddExecutor.add() to check currentWriteHolder instead of writeSheetHolder for applying the row index offset
• Added import for AbstractWriteHolder class
• Added instanceof check before casting to AbstractWriteHolder (unnecessary based on codebase architecture)

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[Copilot]

The instanceof check for AbstractWriteHolder is unnecessary. All implementations of WriteHolder (WriteSheetHolder, WriteTableHolder, WriteWorkbookHolder) extend AbstractWriteHolder. The rest of the codebase directly casts currentWriteHolder() to AbstractWriteHolder without instanceof checks (see WriteHandlerUtils.java lines 79, 124, 160, 168, 176, 184). For consistency with the existing codebase patterns, the cast should be done directly without the instanceof check.

Suggested change

	if (currentWriteHolder instanceof AbstractWriteHolder) {
	AbstractWriteHolder writeHolder = (AbstractWriteHolder) currentWriteHolder;
	if (!writeHolder.getExcelWriteHeadProperty().hasHead()) {
	newRowIndex += currentWriteHolder.relativeHeadRowIndex();
	}
	AbstractWriteHolder writeHolder = (AbstractWriteHolder) currentWriteHolder;
	if (!writeHolder.getExcelWriteHeadProperty().hasHead()) {
	newRowIndex += currentWriteHolder.relativeHeadRowIndex();

[bengbengbalabalabeng]

These tests contain no assertions and therefore do not validate the fix. Please enhance them with assertions that check the actual output. (Also ensure that both XLSX and XLS formats are covered)

[32154678925]

这些测试不包含断言，因此不验证修复。请用检查实际输出的断言来增强它们。（同时确保涵盖XLSX和XLS格式）

谢谢，我修改了测试代码，并且成功跑通测试，且测试了未修改bug的代码，测试是跑不同的。我的代码经验不多，还有什么需要修改的么？

Thank you. I modified the test code and successfully ran through the test. I also tested the code without modifying the bug. The test runs differently. I don't have much code experience. Is there anything I need to change?