背景
如题
在业务中经常遇到这样的需求, 上传excel后对数据进行校验, 如果校验不通过, 需要提供excel下载, 并在后面一列提供错误原因.
常见的做法是在导出的方法中, 加一个字段然后在list中, 然后sheet写到返回流中. 但是如果需要统一样式就比较麻烦, 且每次都需要写这么一串代码.
SheetWriteHandler
我使用的阿里的EasyExcel. 它提供了一个处理器来处理sheet, 相当于拦截器
/*** intercepts handle sheet creation** @author Jiaju Zhuang*/
public interface SheetWriteHandler extends WriteHandler {/*** Called before create the sheet** @param writeWorkbookHolder* @param writeSheetHolder*/void beforeSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder);/*** Called after the sheet is created** @param writeWorkbookHolder* @param writeSheetHolder*/void afterSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder);
}于是我们可以在afterSheetCreate方法中做文章, 统一做处理, 包括实现其他的功能
写一个类来实现这个处理器
/*** 自定义拦截器.新增注释,第一行头加批注**/
@Slf4j
public class AddErrColWriteHandler implements SheetWriteHandler {/*** 第几行*/private final Integer headIdx;private Integer colIdx;private final String errTitle;private Map<Integer, String> errMap;/*** @param headIdx 标题行,为了符合easyexcel的习惯,下标从1开始* @param colIdx 错误所在列. 下标从0开始. 如果没指定,自动取标题行的下一列* @param errTitle* @param errMap 错误信息,key是内容list的下标(为了方便list遍历时传值),最终它的行是 headIdx+errMap+1*/public AddErrColWriteHandler(Integer headIdx, Integer colIdx, String errTitle, Map<Integer, String> errMap) {this.headIdx = headIdx-1;this.colIdx = colIdx;this.errTitle = errTitle;this.errMap = errMap;}/*** @param headIdx 标题行,为了符合easyexcel的习惯,下标从1开始* @param errTitle* @param errMap 错误信息,key是内容list的下标,从0开始(为了方便list遍历时传值),最终它的行是 headIdx+errMap+1*/public AddErrColWriteHandler(Integer headIdx, String errTitle, Map<Integer, String> errMap) {this.headIdx = headIdx-1;this.errTitle = errTitle;this.errMap = errMap;}/*** 表格样式*/private CellStyle cellStyle;private CellStyle cellStyleHeader;@Overridepublic void beforeSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {}@Overridepublic void afterSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {Row row = writeSheetHolder.getCachedSheet().getRow(headIdx);if (row == null) {row = writeSheetHolder.getCachedSheet().createRow(headIdx);}if (colIdx == null){short lastCellNum = row.getLastCellNum();colIdx = (int) lastCellNum;}Cell cell = row.getCell(colIdx);if (cell == null) {cell = row.createCell(colIdx);}Workbook workbook = writeWorkbookHolder.getWorkbook();// 表头样式if (cellStyleHeader == null) {cellStyleHeader = workbook.createCellStyle();cellStyleHeader.setAlignment(HorizontalAlignment.CENTER);cellStyleHeader.setVerticalAlignment(VerticalAlignment.CENTER);cellStyleHeader.setFillForegroundColor(IndexedColors.WHITE.getIndex());Font font = workbook.createFont();font.setFontName("微软雅黑");font.setColor((short) 10);font.setFontHeightInPoints((short) 12);cellStyleHeader.setFont(font);}cell.setCellStyle(cellStyleHeader);cell.setCellValue(errTitle);// 内容样式if (cellStyle == null) {cellStyle = workbook.createCellStyle();
// cellStyle.setAlignment(HorizontalAlignment.CENTER);cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);cellStyle.setFillForegroundColor(IndexedColors.WHITE.getIndex());Font font = workbook.createFont();font.setFontName("微软雅黑");font.setFontHeightInPoints((short) 12);cellStyle.setFont(font);}Sheet sheet = writeSheetHolder.getCachedSheet();for (Map.Entry<Integer, String> en : errMap.entrySet()) {int rowIdx = en.getKey() + headIdx + 1;Row row0 = sheet.getRow(rowIdx);if (row0 == null) {row0 = sheet.createRow(rowIdx);}// 第几列。我这里是1.正常业务根据需求传递Cell cell0 = row0.getCell(colIdx);if (cell0 == null) {cell0 = row0.createCell(colIdx);}cell0.setCellStyle(cellStyle);cell0.setCellValue(en.getValue());}}
}
使用
//在生成导出的数据list方法中
Map<Integer, String> errMap = new HashMap<>();
for (int i = 0; i < list.size(); i++) {if(错误){errMap.put(i, errmsg);}}/*** @param title 错误列的标题名* @param headIdx 标题所在行,为了符合easyexcel的习惯,下标从1开始* @param errMsgMap 错误信息,key是内容list的下标,从0开始(为了方便list遍历时传值),最终它的行是 headIdx+errMap+1
*/EasyExcel.write(os).withTemplate(is).registerWriteHandler(new AddErrColWriteHandler(headIdx,title,errMsgMap)).sheet().doWrite(new ArrayList());}));
)
)
