POI exports excel and displays hierarchically according to parent-child nodes

POI export excel, Hierarchical display according to parent-child nodes

This function has two parts ：

• The first part : Generate excel And export
• The second part : To produce excel Hierarchical display according to parent-child nodes .

The first part is very simple , Skip directly .
reference ：
https://www.cnblogs.com/mingyue1818/p/4828895.html
The second part needs to follow a certain column （ Unit series ） Grading , And fold it up
Ideas ： By observing the data, it can be found that the order has been arranged and 7 level .
1、 Traverse to find the maximum series .maxLevel = 7
2、 First deal with the largest level , That is the first. 7 level ..
First collapse leaf nodes , After folding, the dataset Replace the value in with null
3、 Remove the current leaf node , The parent becomes a leaf node , Collapse superior ; And so on .

Pictured above , Fold first 7 level

On the folding page 6 level

The code is as follows

public class ExcelExportUtil {
    
	public static void exportManySheetExcel(String file, List<ExcelExp> mysheets) {
    
		HSSFWorkbook wb = new HSSFWorkbook();//  Create a workbook 
		List<ExcelExp> sheets = mysheets;

		//  Header style 
		HSSFCellStyle style = wb.createCellStyle();
		style.setAlignment(HSSFCellStyle.ALIGN_CENTER); //  Create a centered format 
		//  Font style 
		HSSFFont fontStyle = wb.createFont();
		fontStyle.setFontName(" Microsoft YaHei ");
		fontStyle.setFontHeightInPoints((short) 12);
		fontStyle.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
		style.setFont(fontStyle);

		for (ExcelExp excel : sheets) {
    
			//  Create a new one sheet
			HSSFSheet sheet = wb.createSheet(excel.getFileName());//  Get the sheet name 
			String[] handers = excel.getHanders();//  obtain sheet Title name of 
			HSSFRow rowFirst = sheet.createRow(0);//  first sheet The first line title 
			//  Write the title 
			for (short i = 0; i < handers.length; i++) {
    
				//  Get each cell in the first row 
				HSSFCell cell = rowFirst.createCell(i);
				//  Write data into cells 
				cell.setCellValue(handers[i]);
				cell.setCellStyle(style); //  Add style 
				sheet.setColumnWidth(i, (short) 6000); //  Set the column width of each column 
			}
			//  Write data sets 
			List<String[]> dataset = excel.getDataset();
			maxJs = 0;
			for (int i = 0; i < dataset.size(); i++) {
    
				String[] data = dataset.get(i);//  Get the object 
				//  Create data rows 
				HSSFRow row = sheet.createRow(i + 1);
				for (short j = 0; j < data.length; j++) {
    
					//  Set the value of the corresponding cell 
					row.createCell(j).setCellValue(data[j]);
				}
				if (StringUtils.isNotEmpty(data[2])) {
    
					getMaxJs(Integer.valueOf(data[2]));
				}
			}
			if (maxJs > 0) {
    
				groupNonDetailLevel(dataset, sheet);
			}
		}
		//  Writing documents 
		try {
    
			FileOutputStream out = new FileOutputStream(new File(file));
			out.flush();
			wb.write(out);
			out.close();
		} catch (FileNotFoundException e) {
    
			e.printStackTrace();
		} catch (IOException e) {
    
			e.printStackTrace();
		}
	}

	static int maxJs = 0;

	/** * * @Description:  Get the maximum number of stages  * @author fhy * @date 2022 year 6 month 22 Japan  */
	public static int getMaxJs(int dwJs) {
    
		if (dwJs > maxJs) {
    
			maxJs = dwJs;
		}
		return maxJs;
	}

	/** * * @Description:  Traverse from large to small according to the series  * @author fhy * @date 2022 year 6 month 22 Japan  */
	public static void groupNonDetailLevel(List<String[]> dataset,HSSFSheet sheet) {
    
		for (int j = maxJs; j > 1; j--) {
    
			groupDetailLevel(dataset,sheet,j);
		}
	}

	/** * * @Description:  Detail level hierarchical display . First collapse leaf nodes , After folding, the dataset Replace the value in with null * （ Remove the current leaf node , The parent becomes a leaf node , Collapse superior ; And so on ） * @author fhy * @date 2022 year 6 month 22 Japan  */
	public static void groupDetailLevel(List<String[]> dataset, HSSFSheet sheet,int level) {
    
		String dwJs = "";
		int startRow, endRow;
		List<Integer> fromRowToRow = new ArrayList<Integer>();
		for (int i = 0; i < dataset.size(); i++) {
    
			String[] data = dataset.get(i);//  Get the object 
			if (null == data) {
    
				continue;
			}
			dwJs = data[2];
			if (level == Integer.valueOf(dwJs)) {
    
				// Get the subscript of the leaf node , Put in list
				fromRowToRow.add(i);
				// empty 
				dataset.set(i, null);
			} else {
    
				if (CollectionUtils.isNotEmpty(fromRowToRow)) {
    
					// from list Take the subscripts of the first and last leaf nodes as the subscripts of the start and end groups 
					startRow = fromRowToRow.get(0);
					endRow = fromRowToRow.get(fromRowToRow.size() - 1);
					sheet.groupRow(startRow + 1, endRow + 1);// grouping 
					sheet.setRowGroupCollapsed(startRow + 1, true);// Fold 
					fromRowToRow.clear();
				}
			}
		}
		if (CollectionUtils.isNotEmpty(fromRowToRow)) {
    
			startRow = fromRowToRow.get(0);
			endRow = fromRowToRow.get(fromRowToRow.size() - 1);
			sheet.groupRow(startRow + 1, endRow + 1);
			sheet.setRowGroupCollapsed(startRow + 1, true);
			fromRowToRow.clear();
		}
	}
}