小编点评

The code you provided describes a custom cell write handler for Excel, which allows you to apply different styles to specific cells or rows based on certain conditions. Here's a summary of the key points: **Custom Cell Write Handler:** * This class handles cell styling for specific situations by storing cell styles in a `cellStyleMap`. * It overrides the `beforeCellCreate`, `afterCellCreate`, and `afterCellDispose` methods to apply styles based on cell values and conditions. * **Before cell creation:** * It checks if the cell contains specific strings like "×" or "未通过". * If it's a header cell, it sets a custom cell style with a specific border, alignment, and font. * **After cell creation:** * If the cell content doesn't contain the specified strings, it applies the default cell style. * If it's a data cell, it sets the border, alignment, and font of the cell to specific values. **Style Setting:** * The `getHeadStyleStrategy` method returns a horizontal cell style strategy that sets the alignment and font for the header cells. * This strategy defines the horizontal alignment (CENTER) and vertical alignment (CENTER) of the header cells. **Condition-Based Styling:** * The code checks for specific cell values (e.g., "×" or "未通过") and applies corresponding styles (e.g., bold, red border). * It also sets the cell style to `null` for certain conditions, effectively disabling it. **Overall, this custom cell write handler allows you to customize cell styles based on various conditions, providing a flexible way to achieve specific formatting requirements.** **Additional Notes:** * The code assumes the presence of a `cellStyleMap` containing predefined cell styles. * The specific styles applied to different cells are not defined in the provided code. * The code relies on the `WriteCellStyle` and `HorizontalCellStyleStrategy` classes for cell styling.

正文

前言

有个需求，需要设置Excel导出的样式，样式如下图所示，有三个表头行，第一个表头行需要加粗和灰色背景，另外两个表头行使用另外的样式，并且当测试结果单元格出现x或者未通过的时候，设置其为红色字体。

实现步骤

写入ExcelSheet的部分代码

 for (Map.Entry<String, List<ExcelDTO>> entry : entries) {
                String excelFileName = entry.getKey() + ".xlsx";
                File tempFile = File.createTempFile(excelTempFolderPath + entry.getKey(), ".xlsx");
                ExcelWriter excelWriter = EasyExcel.write(tempFile).build();

                WriteSheet writeSheet = EasyExcel.
                        writerSheet("sheet")
                        .head(ReceiveCardExcelDTO.class)
                        .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())
                        .registerWriteHandler(new CustomWriteHandler("测试报告"))
                        .registerWriteHandler(new CustomCellWriteHandler())
                        .registerWriteHandler(getHeadStyleStrategy())
                        .build();
                writeSheet.setRelativeHeadRowIndex(1);

                List<List<String>> headTitles = Lists.newArrayList();
                // 固定title
                headTitles.add(Lists.newArrayList("工单号", "卡信息"));
                headTitles.add(Lists.newArrayList(entry.getKey(), "升级固件"));
                headTitles.add(Lists.newArrayList(entry.getKey(), "SDRAM"));
                headTitles.add(Lists.newArrayList("型号", "HUB"));
          
     headTitles.add(Lists.newArrayList(receiveCardOrderMap.get(entry.getValue().get(0).getMark()).getReceiveCardType(), "网口"));
                headTitles.add(Lists.newArrayList("测试时间", "测试结果"));
                headTitles.add(Lists.newArrayList(cn.hutool.core.date.DateUtil.format(entry.getValue().get(0).getTestTime(), "yyyy-MM-dd HH:mm:ss"), "详情"));
                writeSheet.setHead(headTitles);
                excelWriter.write(entry.getValue(), writeSheet);
                excelWriter.finish();

重点是如下几个handler，下面会进行讲解

            WriteSheet writeSheet = EasyExcel.
                    writerSheet("sheet")
                    .head(ReceiveCardExcelDTO.class)
                    .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())
                    .registerWriteHandler(new CustomWriteHandler("测试报告"))
                    .registerWriteHandler(new CustomCellWriteHandler())
                    .registerWriteHandler(getHeadStyleStrategy())
                    .build();

测试报告标题行的实现

这里对应的是CustomWriteHandler类

/********************************
 *  @interface : CustomWriteHandler
 *  @function  : 添加excel head额外内容
 *  @date      : 2024.04.23 11:13
 *  @author    : zh
 ********************************/
public class CustomWriteHandler implements SheetWriteHandler {

    private String title;


    public CustomWriteHandler(String title) {
        this.title = title;
    }

    @Override
    public void beforeSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {

    }

    @Override
    public void afterSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
        Workbook workbook = writeWorkbookHolder.getWorkbook();
        Sheet sheet = workbook.getSheet(writeSheetHolder.getSheetName());
        Row row1 = sheet.getRow(0);
        if (row1 == null) {
            row1 = sheet.createRow(0);
        }
        row1.setHeight((short) 500);
        Cell cell1 = row1.getCell(0);
        if (cell1 == null) {
            cell1 = row1.createCell(0);
        }
        cell1.setCellValue(title);
        CellStyle cellStyle = workbook.createCellStyle();

        Font font = workbook.createFont();
        font.setBold(true);
        font.setFontHeight((short) 220);
        font.setFontName("宋体");
    
        sheet.addMergedRegionUnsafe(new CellRangeAddress(0, 0, 0, 6));

        CellStyle headStyle = workbook.createCellStyle();
        headStyle.setFont(font);
        headStyle.setAlignment(HorizontalAlignment.CENTER);
        headStyle.setVerticalAlignment(VerticalAlignment.CENTER);
        // 设置表头背景色为灰色
        headStyle.setFillForegroundColor(IndexedColors.GREY_25_PERCENT.getIndex());
        headStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);


        CellStyle contentStyle = workbook.createCellStyle();
        contentStyle.setAlignment(HorizontalAlignment.CENTER);
        contentStyle.setVerticalAlignment(VerticalAlignment.CENTER);
        contentStyle.setBorderTop(BorderStyle.THIN);
        contentStyle.setBorderBottom(BorderStyle.THIN);
        contentStyle.setBorderLeft(BorderStyle.THIN);
        contentStyle.setBorderRight(BorderStyle.THIN);

        for (Row row : sheet) {
            if (row.getRowNum() == 0) {
                for (Cell cell : row) {
                    // 表头
                    cell.setCellStyle(headStyle);
                }
                break;
            }
        }
    }
}

在这里register并填入相关的标题，到此第一行标题头设置完毕。

这里其实就是相当于这行标题是独立开来设置的，先预留了第一行的位置，然后后续把标题插入这行，后面再针对这行设置独立的样式。

其他标题行的设置

可以看到每个list都有两个元素

List<List<String>> headTitles = Lists.newArrayList();
                // 固定title
                headTitles.add(Lists.newArrayList("工单号", "卡信息"));
                headTitles.add(Lists.newArrayList(entry.getKey(), "升级固件"));
                headTitles.add(Lists.newArrayList(entry.getKey(), "SDRAM"));
                headTitles.add(Lists.newArrayList("型号", "HUB"));

对比excel标题

可以看到其实每个list都是两行标题竖着的两个内容，第一个列标题两行就分别是工单号，卡信息；第二列因为涉及到合并，所以出现了两个entry.getKey()对应不同的两个内容（升级固件和SDRAM)，依次类推；

标题行样式的设定

对应这个registerWriteHandler(getHeadStyleStrategy())

调getHeadStyleStrategy()方法，返回了一个策略，这里只设置了header的样式

    public static HorizontalCellStyleStrategy getHeadStyleStrategy() {
        // 头的策略  样式调整
        WriteCellStyle headWriteCellStyle = new WriteCellStyle();
        // 水平对齐方式
        headWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);
        headWriteCellStyle.setFillPatternType(FillPatternType.NO_FILL);
        WriteFont headWriteFont = new WriteFont();
        headWriteFont.setBold(false);
        headWriteFont.setFontHeightInPoints((short) 12);
        headWriteCellStyle.setWriteFont(headWriteFont);
        // 垂直对齐方式
        headWriteCellStyle.setVerticalAlignment(VerticalAlignment.CENTER);

        return new HorizontalCellStyleStrategy(headWriteCellStyle, (List<WriteCellStyle>) null);
    }

特定单元格样式的修改

对应了这个.registerWriteHandler(new CustomCellWriteHandler())

/********************************
 *  @interface : CustomCellWriteHandler
 *  @function  : 处理excel特定内容格式
 *  @date      : 2024.04.23 11:13
 *  @author    : zh
 ********************************/
public class CustomCellWriteHandler implements CellWriteHandler {


    Map<String,CellStyle> cellStyleMap = new HashMap<>();



    @Override
    public void beforeCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row, Head head, Integer columnIndex, Integer relativeRowIndex, Boolean isHead) {

    }

    @Override
    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {

    }

    @Override
    public void afterCellDispose(CellWriteHandlerContext context) {
        Cell cell = context.getCell();
        int rowIndex = cell.getRowIndex();
        int cellIndex = cell.getColumnIndex();

        // 自定义样式处理
        // 当前事件会在 数据设置到poi的cell里面才会回调
        // 判断不是头的情况 如果是fill 的情况 这里会==null 所以用not true
        if (BooleanUtils.isNotTrue(context.getHead())) {
            if (cell.getStringCellValue().contains("×") || cell.getStringCellValue().contains("未通过")) {
                CellStyle cellStyle = null;
                if (cellStyleMap.get("red") != null) {
                    cellStyle = cellStyleMap.get("red");
                } else {
                    // 拿到poi的workbook
                    Workbook workbook = context.getWriteWorkbookHolder().getWorkbook();
                    // 这里能复用的地方缓存起来 一个表格最多创建6W个样式
                    // 不同单元格传同一个cellStyle
                    cellStyle = workbook.createCellStyle();
                    cellStyle.setBorderBottom(BorderStyle.THIN);
                    cellStyle.setBorderTop(BorderStyle.THIN);
                    cellStyle.setBorderLeft(BorderStyle.THIN);
                    cellStyle.setBorderRight(BorderStyle.THIN);
                    cellStyle.setAlignment(HorizontalAlignment.CENTER);
                    Font font = workbook.createFont();
                    font.setColor(Font.COLOR_RED);
                    cellStyle.setFont(font);
                    cellStyleMap.put("red", cellStyle);
                }
                cell.setCellStyle(cellStyle);
                // 由于这里没有指定dataformat 最后展示的数据 格式可能会不太正确
                // 这里要把 WriteCellData的样式清空， 不然后面还有一个拦截器 FillStyleCellWriteHandler 默认会将 WriteCellStyle 设置到
                // cell里面去 会导致自己设置的不一样
                context.getFirstCellData().setWriteCellStyle(null);
            }
        }


    }
}

到此就可以实现上述excel样式了。