Easyexcel（5-自定义列宽）
注解@ColumnWidth
@Datapublic class WidthAndHeightData { @ExcelProperty("字符串标题") private String string; @ExcelProperty("日期标题") private Date date; @ColumnWidth(50) @ExcelProperty("数字标题") private Double doubleData;}注解使用时表头长度无法做到动态调整，只能固定设置，每次调整表头长度时只能重新修改代码
注意：@ColumnWidth最大值只能为255，超过255*256长度时会报错
查看XSSFSheet源码
类方法
AbstractHeadColumnWidthStyleStrategy
public abstract class AbstractHeadColumnWidthStyleStrategy extends AbstractColumnWidthStyleStrategy { @Override protected void setColumnWidth(WriteSheetHolder writeSheetHolder, List<WriteCellData<?>> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) { // 判断是否满足 当前行索引不为空 && （当前是表头 || 当前行索引是首行） // 如果不满足，则说明不是表头，不需要设置 boolean needSetWidth = relativeRowIndex != null && (isHead || relativeRowIndex == 0); if (!needSetWidth) { return; } Integer width = columnWidth(head, cell.getColumnIndex()); if (width != null) { width = width * 256; writeSheetHolder.getSheet().setColumnWidth(cell.getColumnIndex(), width); } } protected abstract Integer columnWidth(Head head, Integer columnIndex);}通过继承AbstractHeadColumnWidthStyleStrategy类，实现columnWidth方法获取其对应列的宽度
SimpleColumnWidthStyleStrategy
源码查看
public class SimpleColumnWidthStyleStrategy extends AbstractHeadColumnWidthStyleStrategy { private final Integer columnWidth; public SimpleColumnWidthStyleStrategy(Integer columnWidth) { this.columnWidth = columnWidth; } @Override protected Integer columnWidth(Head head, Integer columnIndex) { return columnWidth; }}基本使用
通过registerWriteHandler设置策略方法调整每列的固定宽度
@Datapublic class User { @ExcelProperty(value = "用户Id") private Integer userId; @ExcelProperty(value = "姓名") private String name; @ExcelProperty(value = "手机") private String phone; @ExcelProperty(value = "邮箱") private String email; @ExcelProperty(value = "创建时间") private Date createTime;}@GetMapping("/download2")public void download2(HttpServletResponse response) { try { response.setContentType("application/vnd.ms-excel"); response.setCharacterEncoding("utf-8"); // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系 String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20"); response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls"); User user = new User(); user.setUserId(123); user.setName("asplplplplpplplplplpl"); user.setPhone("15245413"); user.setEmail("54565454@qq.com"); user.setCreateTime(new Date()); EasyExcel.write(response.getOutputStream(), User.class) .sheet("模板") .registerWriteHandler(new SimpleColumnWidthStyleStrategy(20)) .doWrite(Arrays.asList(user)); } catch (Exception e) { e.printStackTrace(); }}
LongestMatchColumnWidthStyleStrategy
源码查看
public class LongestMatchColumnWidthStyleStrategy extends AbstractColumnWidthStyleStrategy { private static final int MAX_COLUMN_WIDTH = 255; private final Map<Integer, Map<Integer, Integer>> cache = MapUtils.newHashMapWithExpectedSize(8); @Override protected void setColumnWidth(WriteSheetHolder writeSheetHolder, List<WriteCellData<?>> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) { // 判断 是否为表头 || 导出内容是否为空 boolean needSetWidth = isHead || !CollectionUtils.isEmpty(cellDataList); if (!needSetWidth) { return; } Map<Integer, Integer> maxColumnWidthMap = cache.computeIfAbsent(writeSheetHolder.getSheetNo(), key -> new HashMap<>(16)); Integer columnWidth = dataLength(cellDataList, cell, isHead); if (columnWidth < 0) { return; } // 超过最大值255时则设置为255 if (columnWidth > MAX_COLUMN_WIDTH) { columnWidth = MAX_COLUMN_WIDTH; } // 比较该列的宽度，如果比原来的宽度大，则重新设置 Integer maxColumnWidth = maxColumnWidthMap.get(cell.getColumnIndex()); if (maxColumnWidth == null || columnWidth > maxColumnWidth) { maxColumnWidthMap.put(cell.getColumnIndex(), columnWidth); writeSheetHolder.getSheet().setColumnWidth(cell.getColumnIndex(), columnWidth * 256); } } private Integer dataLength(List<WriteCellData<?>> cellDataList, Cell cell, Boolean isHead) { // 如果是表头，则返回表头的宽度 if (isHead) { return cell.getStringCellValue().getBytes().length; } // 如果是单元格内容，则根据类型返回其内容的宽度 WriteCellData<?> cellData = cellDataList.get(0); CellDataTypeEnum type = cellData.getType(); if (type == null) { return -1; } switch (type) { case STRING: return cellData.getStringValue().getBytes().length; case BOOLEAN: return cellData.getBooleanValue().toString().getBytes().length; case NUMBER: return cellData.getNumberValue().toString().getBytes().length; default: return -1; } }}LongestMatchColumnWidthStyleStrategy是一个列宽自适应策略。当我们在写入Excel数据时，如果希望根据数据的实际长度来自适应调整列宽，就可以使用这个策略。它会遍历指定列的所有数据（包括表头），找出最长的数据，然后根据这个最长数据的长度来设定该列的宽度，确保数据在单元格内不会被截断。
根据官网介绍：这个目前不是很好用，比如有数字就会导致换行。而且长度也不是刚好和实际长度一致。 所以需要精确到刚好列宽的慎用。
基本使用
@GetMapping("/download1")public void download1(HttpServletResponse response) { try { response.setContentType("application/vnd.ms-excel"); response.setCharacterEncoding("utf-8"); // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系 String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20"); response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls"); User user = new User(); user.setUserId(123); user.setName("asplplplplpplplplplpl"); user.setPhone("15245413"); user.setEmail("54565454@qq.com"); user.setCreateTime(new Date()); EasyExcel.write(response.getOutputStream(), User.class) .sheet("模板") .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()) .doWrite(Arrays.asList(user)); } catch (Exception e) { e.printStackTrace(); }}
表头宽度工具类
仿照LongestMatchColumnWidthStyleStrategy源码自定义工具类
使用构造器传参的方式，用户可以自定义通过表头或者单元格内容长度来设置列宽，通过修改常数值和比例可以自己设置想调整的列宽
/** * 表头宽度根据表头或数据内容自适应 */public class CustomWidthStyleStrategy extends AbstractColumnWidthStyleStrategy { /** * 1-根据表头宽度，2-根据单元格内容 */ private Integer type; private Map<Integer, Map<Integer, Integer>> cache = new HashMap<>(); public CustomWidthStyleStrategy(Integer type) { this.type = type; } /** * 设置列宽 * * @param writeSheetHolder 写入Sheet的持有者 * @param cellDataList 当前列的单元格数据列表 * @param cell 当前单元格 * @param head 表头 * @param relativeRowIndex 当前行的相对索引 * @param isHead 是否为表头 */ @Override protected void setColumnWidth(WriteSheetHolder writeSheetHolder, List<WriteCellData<?>> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) { if (type == 1) { if (isHead) { int columnWidth = cell.getStringCellValue().length(); columnWidth = Math.max(columnWidth * 2, 20); if (columnWidth > 255) { columnWidth = 255; } writeSheetHolder.getSheet().setColumnWidth(cell.getColumnIndex(), columnWidth * 256); } return; } //不把标头计算在内 boolean needSetWidth = isHead || !CollectionUtils.isEmpty(cellDataList); if (needSetWidth) { Map<Integer, Integer> maxColumnWidthMap = cache.get(writeSheetHolder.getSheetNo()); if (maxColumnWidthMap == null) { maxColumnWidthMap = new HashMap<>(); cache.put(writeSheetHolder.getSheetNo(), maxColumnWidthMap); } Integer columnWidth = this.dataLength(cellDataList, cell, isHead); if (columnWidth >= 0) { if (columnWidth > 255) { columnWidth = 255; } Integer maxColumnWidth = maxColumnWidthMap.get(cell.getColumnIndex()); if (maxColumnWidth == null || columnWidth > maxColumnWidth) { maxColumnWidthMap.put(cell.getColumnIndex(), columnWidth); writeSheetHolder.getSheet().setColumnWidth(cell.getColumnIndex(), columnWidth * 256); } } } } /** * 数据长度 * * @param cellDataList * @param cell * @param isHead * @return */ private Integer dataLength(List<WriteCellData<?>> cellDataList, Cell cell, Boolean isHead) { //头直接返回原始长度 if (isHead) { return cell.getStringCellValue().getBytes().length; } else { //不是头的话看是什么类型用数字加就可以了 WriteCellData cellData = cellDataList.get(0); CellDataTypeEnum type = cellData.getType(); if (type == null) { return -1; } else { switch (type) { case STRING: return cellData.getStringValue().getBytes().length + 1; case BOOLEAN: return cellData.getBooleanValue().toString().getBytes().length; case NUMBER: return cellData.getNumberValue().toString().getBytes().length * 2; case DATE: return cellData.getDateValue().toString().length() + 1; default: return -1; } } } }}@GetMapping("/download3")public void download3(HttpServletResponse response) { try { response.setContentType("application/vnd.ms-excel"); response.setCharacterEncoding("utf-8"); // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系 String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20"); response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls"); User user = new User(); user.setUserId(123); user.setName("asplplplplpplplplplpl"); user.setPhone("15245413"); user.setEmail("54565454@qq.com"); user.setCreateTime(new Date()); EasyExcel.write(response.getOutputStream(), User.class) .sheet("模板") .registerWriteHandler(new CustomWidthStyleStrategy(1)) .doWrite(Arrays.asList(user)); } catch (Exception e) { e.printStackTrace(); }}@GetMapping("/download4")public void download4(HttpServletResponse response) { try { response.setContentType("application/vnd.ms-excel"); response.setCharacterEncoding("utf-8"); // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系 String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20"); response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls"); User user = new User(); user.setUserId(123); user.setName("asplplplplpplplplplpl"); user.setPhone("15245413"); user.setEmail("54565454@qq.com"); user.setCreateTime(new Date()); EasyExcel.write(response.getOutputStream(), User.class) .sheet("模板") .registerWriteHandler(new CustomWidthStyleStrategy(2)) .doWrite(Arrays.asList(user)); } catch (Exception e) { e.printStackTrace(); }}运行结果
[*]使用表头设置的列宽
[*]使用单元格内容设置的列宽
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