【EasyExcel】导出excel并支持自定义设置数据行背景颜色等-编程知识

需求背景：

根据查询条件将列表数据导出，并筛选出满足某个条件的数据，将满足条件的数据的背景颜色设置成黄色。
（本文例子如：name出现的次数大于等于2，将相关数据背景颜色都设置为黄色）

一、技术选型：

1、easyExcel的自定义写策略处理：CellWriteHandler

2、poi自带的写数据行处理：Workbook

思考选定:

由于目前系统中多处使用的是file插件导出类，是由统一形成的，直接改动，对其它项目引入，从而导出的性能产生一定的影响，所以选择自定义策略实现，故选1。

二、方案设计：（基于实现 CellWriteHandler 接口）

1、在 beforeCellCreate 方法中统计出每个数据行的 name 出现的次数，在 afterCellDispose 方法中处理满足设置背景颜色数据的背景颜色。

2、直接传入数据行的索引，在 afterCellDispose 方法中处理满足设置背景颜色数据的背景颜色。

note：原本考虑的是选择1，但是在实现的时候，统计name出现次数一直会出现问题，在easeExcel的源码中：beforeCellCreate 操作数据出现问题，待处理。（码友们可自行尝试！！！）故暂选择方案2 实现当前需求。

三、代码实现：

pom.xml:

<dependency><groupId>com.alibaba</groupId><artifactId>easyexcel</artifactId><version>3.3.2</version>
</dependency>

API：

 @ApiOperation(value = "评论审核导出")@GetMapping(value = "/export")public void exportExcel(HttpServletResponse response, TestParam param) throws BaseException {service.export(response, param);}

实现层：

public class TestExcelService {private static final String FILE_NAME = "测试文件名字";private static final String SHEET_NAME = "测试";private final IEasyExcelService easyExcelService;public SeedDemandExcelService(IEasyExcelService easyExcelService) {this.easyExcelService = easyExcelService;}public void export(HttpServletResponse response, TestParam param) throws BaseException{// 根据查询参数获取查询到的数据（根据自己的查询方法在这里将数据查询出来）List<TestExcelData> exportData = this.getExportData(param);// Obtain data rows that require background color settings// 获取需要设置背景颜色的数据行索引List<Integer> index = getIndexList(exportData);// exporttry {easyExcelService.exportExcelWithBackGround(exportData, response, DemoExcelData.class, FILE_NAME, SHEET_NAME, index);} catch (Exception e) {throw new Exception(CodeEnum.FAILED, "导出异常，请联系开发人员！异常信息是：" + e.getMessage());}}
}

工具类：IEasyExcelService

public interface IEasyExcelService {/*** 导出excel方法* @param exportData 需要导出的数据* @param response response* @param tClass 导出excel的字段实体类* @param fileName 文件名字* @param sheetName sheet名字*/<T> void exportExcel(List<T> exportData, HttpServletResponse response, Class<T> tClass, String fileName, String sheetName);/*** 导出excel方法（支持设置背景颜色）* @param exportData 需要导出的数据* @param response response* @param tClass 导出excel的字段实体类* @param fileName 文件名字* @param sheetName sheet名字* @param backGroundIndex 需要设置背景的数据行* @param <T> t* @throws Exception Exception*/<T> void exportExcelWithBackGround(List<T> exportData, HttpServletResponse response, Class<T> tClass , String fileName, String sheetName, List<Integer> backGroundIndex) throws Exception;
}

工具类：EasyExcelServiceImpl

@Service
@Slf4j
public class EasyExcelServiceImpl implements IEasyExcelService {@Overridepublic <T> void exportExcel(List<T> exportData, HttpServletResponse response, Class<T> tClass, String fileName, String sheetName){try{// 使用swagger 会导致各种问题，直接用浏览器或者用postmanresponse.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");response.setCharacterEncoding("utf-8");// fileName encoderString fileNameEncoder = URLEncoder.encode(fileName, "UTF-8").replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileNameEncoder + ".xlsx");// write to excelEasyExcelFactory.write(response.getOutputStream(), tClass).autoCloseStream(Boolean.FALSE).sheet(sheetName).doWrite(exportData);}catch (Exception e){log.error("EasyExcelServiceImpl->exportExcel error, message is :{}", e.getMessage());}}@Overridepublic <T> void exportExcelWithBackGround(List<T> exportData, HttpServletResponse response, Class<T> tClass,String fileName, String sheetName, List<Integer> backGroundIndex) throws Exception {// 使用swagger 会导致各种问题，直接用浏览器或者用postmanresponse.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");response.setCharacterEncoding("utf-8");// fileName encoderString fileNameEncoder = URLEncoder.encode(fileName, "UTF-8").replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileNameEncoder + ".xlsx");// 自定义策略Set<Integer> yellowRowsSet = new HashSet<>(backGroundIndex);SeedDemandCellWriteHandler seedDemandCellWriteHandler = new SeedDemandCellWriteHandler(yellowRowsSet);// write to excelEasyExcelFactory.write(response.getOutputStream(), tClass)// 自定义背景颜色策略.registerWriteHandler(seedDemandCellWriteHandler).inMemory(Boolean.TRUE).autoCloseStream(Boolean.FALSE).sheet(sheetName).doWrite(exportData);}}

(其中registerWriteHandler支持扩展多个，可以通过HorizontalCellStyleStrategy策略设置全局的配置，如背景颜色、字体、合并单元格等)

自定义Handle:（自定义设置数据行背景颜色）

import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.metadata.data.WriteCellData;
import com.alibaba.excel.util.BooleanUtils;
import com.alibaba.excel.write.handler.CellWriteHandler;
import com.alibaba.excel.write.handler.context.CellWriteHandlerContext;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.metadata.holder.WriteTableHolder;
import com.alibaba.excel.write.metadata.style.WriteCellStyle;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.FillPatternType;
import org.apache.poi.ss.usermodel.IndexedColors;
import org.apache.poi.ss.usermodel.Row;
import java.util.Set;/*** @author c*/
public class CustomCellWriteHandler implements CellWriteHandler {/*** 标黄行宽集合*/private final Set<Integer> yellowRowIndex;public CustomCellWriteHandler(Set<Integer> yellowRowIndex) {this.yellowRowIndex = yellowRowIndex;}@Overridepublic void beforeCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row, Head head, Integer columnIndex, Integer relativeRowIndex, Boolean isHead) {// 源码context中row待优化：支持入参 获取需要字段的出现次数 从而设置背景颜色// to do：（row.getCell(columnIndex)失效）}@Overridepublic void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {// empty}@Overridepublic void afterCellDispose(CellWriteHandlerContext context) {if (BooleanUtils.isNotTrue(context.getHead())) {// 获取当前行的行号Integer currentRowIndex = context.getRowIndex();// 判断当前行是否在yellowRowIndex's中if (yellowRowIndex.contains(currentRowIndex)) {// 设置背景颜色，也可以设置字体等其它元素WriteCellData<?> cellData = context.getFirstCellData();WriteCellStyle writeCellStyle = cellData.getOrCreateStyle();writeCellStyle.setFillForegroundColor(IndexedColors.YELLOW.getIndex());writeCellStyle.setFillPatternType(FillPatternType.SOLID_FOREGROUND);}}}}

DemoExcelData:(导出字段实体类)

@Data
@EqualsAndHashCode
public class DemoExcelData{@ExcelProperty(value = "TaskID", index = 0)private String name;@ExcelProperty(value = "taskName", index = 1)private String sex;@ExcelProperty(value = "taskName", index = 2)private String age;
}