Java利用EasyExcel解析动态表头及导出实现过程
短信预约 -IT技能 免费直播动态提醒
前言
excel文件导入及导出，是日常开发中经常遇到的需求。本次笔者以EasyExcel为例，针对在项目中遇到的动态表头解析及导出的场景，详细介绍具体的代码实现过程。
参考地址
https://github.com/alibaba/easyexcel
前端下载
const download = () => {
axios({
method: 'GET',
url: config.http.baseUrl + '/templateDownload',
responseType: 'blob',
})
.then(function (res) {
const content = res.data
const blob = new Blob([content], { type: "application/application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" })
const downloadElement = document.createElement("a");
const href = window.URL.createObjectURL(blob);
downloadElement.href = href;
downloadElement.download = decodeURI(res.headers['filename']);
document.body.appendChild(downloadElement);
downloadElement.click();
document.body.removeChild(downloadElement); // 下载完成移除元素
window.URL.revokeObjectURL(href); // 释放掉blob对象
})
}
模板下载
excel文件导入功能，常常需要进行模板下载，在springboot项目中，程序是以jar包的形式运行的，所以有很多小伙伴常常
遇到在本地开发中能够实现下载功能，但部署到服务器的时候，找不到模板文件的问题。
@Override
public void templateDownload(HttpServletResponse response, HttpServletRequest request) {
//获取要下载的模板名称
String fileName = "批量导入模板.xlsx";
//获取文件下载路径
String filePath = "/template/template.xlsx";
TemplateDownloadUtil.download(response, request, fileName, filePath);
}
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.io.ClassPathResource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;
@Slf4j
public class TemplateDownloadUtil {
public static void download(HttpServletResponse response, HttpServletRequest request,String fileName,String filePath){
try {
response.setContentType("application/application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
response.setCharacterEncoding("utf-8");
// 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系
response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(fileName, "UTF-8"));
response.setHeader("filename", URLEncoder.encode(fileName, "UTF-8"));
response.setHeader("Access-Control-Expose-Headers", "filename,Content-Disposition");
//获取文件的路径，此方式本地开发可以运行，服务器无法获取文件
// String filePath = getClass().getResource("/template/template.xlsx").getPath();
// FileInputStream input = new FileInputStream(filePath);
//在服务器中能够读取到模板文件
ClassPathResource resource = new ClassPathResource(filePath);
InputStream input = resource.getInputStream();
OutputStream out = response.getOutputStream();
byte[] b = new byte[2048];
int len;
while ((len = input.read(b)) != -1) {
out.write(b, 0, len);
}
//修正 Excel在“xxx.xlsx”中发现不可读取的内容。是否恢复此工作薄的内容？如果信任此工作簿的来源，请点击"是"
// response.setHeader("Content-Length", String.valueOf(input.getChannel().size()));
input.close();
} catch (Exception e) {
log.error("下载模板失败 :", e);
}
}
}EasyExcel动态表头解析
EasyExcel简单的读文件，官网中已经有详细的说明，本文不再赘述。
本文主要针对笔者遇到的复杂表头及动态表头进行讲解。
模板示例
解析
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
@Slf4j
@Data
public class BatchReadListener extends AnalysisEventListener<Map<Integer, String>> {
private static final int BATCH_COUNT = 500;
//Excel数据缓存结构
private List<Map<Integer, Map<Integer, String>>> list = new ArrayList<>();
//Excel表头（列名）数据缓存结构
private Map<Integer, String> headTitleMap = new HashMap<>();
private DbFileBatchService dbFileBatchService;
private DbFileContentService dbFileContentService;
private FileBatch fileBatch;
private int total = 0;
public BatchReadListener(DbFileBatchService dbFileBatchService, DbFileContentService dbFileContentService, FileBatch fileBatch) {
this.dbFileBatchService = dbFileBatchService;
this.dbFileContentService = dbFileContentService;
this.fileBatch = fileBatch;
}
@Override
public void invoke(Map<Integer, String> data, AnalysisContext context) {
log.info("解析到一条数据:{}", JSON.toJSONString(data));
total++;
Map<Integer, Map<Integer, String>> map = new HashMap<>();
map.put(context.readRowHolder().getRowIndex(), data);
list.add(map);
// 达到BATCH_COUNT了，需要去存储一次数据库，防止数据几万条数据在内存，容易OOM
if (list.size() >= BATCH_COUNT) {
saveData();
// 存储完成清理 list
list.clear();
}
}
@Override
public void doAfterAllAnalysed(AnalysisContext context) {
// 这里也要保存数据，确保最后遗留的数据也存储到数据库
saveData();
log.info("所有数据解析完成！");
}
@Override
public void invokeHeadMap(Map<Integer, String> headMap, AnalysisContext context) {
log.info("表头数据：{}", JSONObject.toJSONString(headMap));
headTitleMap = headMap;
}
private void saveData() {
log.info("{}条数据，开始存储数据库！", list.size());
FileContent fileContent = null;
List<FileContent> fileContentList = list.stream().flatMap(
integerMap -> integerMap.entrySet().stream().map(entrySet -> {
//entrySet.getKey()获取的是内容的RowIndex,实际的行数需要根据表头数进行处理
Integer rowIndex = entrySet.getKey();
Map<Integer, String> value = entrySet.getValue();
log.info(JSONObject.toJSONString(value));
fileContent = new FileContent();
fileContent.setBatchId(fileBatch.getId());
fileContent.setBatchNo(fileBatch.getBatchNo());
//固定字段入库
fileContent.setName(value.get(0) != null ? value.get(0).trim() : "");
fileContent.setCertNo(value.get(1) != null ? value.get(1).trim() : "");
fileContent.setRealAmount(value.get(2) != null ? value.get(2).trim() : "");
//所有动态表头数据转为JSON串入库
fileContent.setFieldsValue(JSONObject.toJSONString(value));
//取实际的内容rowIndex
fileContent.setRowNum(rowIndex + 1);
fileContent.setCreateTime(LocalDateTime.now());
return xcSalaryFileContent;
}
)).collect(Collectors.toList());
log.info(JSONObject.toJSONString(fileContentList));
dbFileContentService.saveBatch(fileContentList);
log.info("存储数据库成功！");
}
} BatchReadListener listener = new BatchReadListener(dbFileBatchService, dbFileContentService, fileBatch);
try {
//注：headRowNumber默认为1，现赋值为2，即从第三行开始读取内容
EasyExcel.read(fileInputStream, listener).headRowNumber(2).sheet().doRead();
} catch (Exception e) {
log.info("EasyExcel解析文件失败，{}", e);
throw new CustomException("文件解析失败，请重新上传");
}
//获取表头信息进行处理
Map<Integer, String> headTitleMap = listener.getHeadTitleMap();
//获取动态表头信息
List<String> headList = headTitleMap.keySet().stream().map(key -> {
String head = headTitleMap.get(key);
log.info(head);
return head == null ? "" : head.replace("*", "");
}).collect(Collectors.toList());
//可以对表头进行入库保存，方便后续导出
综上，动态表头即可完成解析。
EasyExcel动态表头导出
导出示例
获取动态头
private List<List<String>> getFileHeadList( FileBatch fileBatch) {
String head = fileBatch.getFileHead();
List<String> headList = Arrays.asList(head.split(","));
List<List<String>> fileHead = headList.stream().map(item -> concatHead(Lists.newArrayList(item))).collect(Collectors.toList());
fileHead.add(concatHead(Lists.newArrayList("备注")));
return fileHead;
}
private List<String> concatHead(List<String> headContent) {
String remake = "填写须知： \n" +
"1.系统自动识别Excel表格，表头必须含有“企业账户号”、“企业账户名”、“实发金额”；\n" +
"2.带 “*” 为必填字段，填写后才能上传成功；\n" +
"3.若需上传其他表头，可自行在“实发金额”后添加表头，表头最多可添加20个，表头名称请控制在8个字以内；\n" +
"4.填写的表头内容不可超过30个字；\n" +
"5.实发金额支持填写到2位小数；\n" +
"6.每次导入数据不超过5000条。\n" +
"\n" +
"注：请勿删除填写须知，删除后将导致文件上传失败\n" +
"\n" +
"表头示例：";
headContent.add(0, remake);
return headContent;
}
获取数据
List<FileContent> fileContentList = dbFileContentService.list(
Wrappers.<FileContent>lambdaQuery()
.eq(FileContent::getBatchId, fileBatch.getId())
.orderByAsc(FileContent::getRowNum)
);
List<List<Object>> contentList = fileContentList.stream().map(fileContent -> {
List<Object> rowList = new ArrayList<>();
String fieldsValue = fileContent.getFieldsValue();
JSONObject contentObj = JSONObject.parseObject(fieldsValue);
for (int columnIndex = 0 , length = headList.size(); columnIndex < length; columnIndex++) {
Object content = contentObj.get(columnIndex);
rowList.add(content == null ? "" : content);
}
rowList.add(fileContent.getCheckMessage());
return rowList;
}).collect(Collectors.toList());
单元格格式设置
import com.alibaba.excel.metadata.data.DataFormatData;
import com.alibaba.excel.metadata.data.WriteCellData;
import com.alibaba.excel.write.handler.context.CellWriteHandlerContext;
import com.alibaba.excel.write.metadata.style.WriteCellStyle;
import com.alibaba.excel.write.metadata.style.WriteFont;
import com.alibaba.excel.write.style.HorizontalCellStyleStrategy;
import org.apache.poi.ss.usermodel.BorderStyle;
import org.apache.poi.ss.usermodel.HorizontalAlignment;
import org.apache.poi.ss.usermodel.IndexedColors;
import java.util.List;
public class CellStyleStrategy extends HorizontalCellStyleStrategy {
private final WriteCellStyle headWriteCellStyle;
private final WriteCellStyle contentWriteCellStyle;
private final List<Integer> columnIndexes;
public CellStyleStrategy(List<Integer> columnIndexes,WriteCellStyle headWriteCellStyle, WriteCellStyle contentWriteCellStyle) {
this.columnIndexes = columnIndexes;
this.headWriteCellStyle = headWriteCellStyle;
this.contentWriteCellStyle = contentWriteCellStyle;
}
//设置头样式
@Override
protected void setHeadCellStyle( CellWriteHandlerContext context) {
// 获取字体实例
WriteFont headWriteFont = new WriteFont();
headWriteFont.setFontName("宋体");
//表头不同处理
if (columnIndexes.get(0).equals(context.getRowIndex())) {
headWriteCellStyle.setFillForegroundColor(IndexedColors.WHITE.getIndex());
headWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.LEFT);
headWriteFont.setFontHeightInPoints((short) 12);
headWriteFont.setBold(false);
headWriteFont.setFontName("宋体");
}else{
headWriteCellStyle.setFillForegroundColor(IndexedColors.GREY_25_PERCENT.getIndex());
headWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);
headWriteFont.setFontHeightInPoints((short) 11);
headWriteFont.setBold(false);
headWriteFont.setFontName("微软雅黑");
}
headWriteCellStyle.setWriteFont(headWriteFont);
DataFormatData dataFormatData = new DataFormatData();
dataFormatData.setIndex((short)49);
headWriteCellStyle.setDataFormatData(dataFormatData);
if (stopProcessing(context)) {
return;
}
WriteCellData<?> cellData = context.getFirstCellData();
WriteCellStyle.merge(headWriteCellStyle, cellData.getOrCreateStyle());
}
//设置填充数据样式
@Override
protected void setContentCellStyle(CellWriteHandlerContext context) {
WriteFont contentWriteFont = new WriteFont();
contentWriteFont.setFontName("宋体");
contentWriteFont.setFontHeightInPoints((short) 11);
//设置数据填充后的实线边框
contentWriteCellStyle.setWriteFont(contentWriteFont);
contentWriteCellStyle.setBorderLeft(BorderStyle.THIN);
contentWriteCellStyle.setBorderTop(BorderStyle.THIN);
contentWriteCellStyle.setBorderRight(BorderStyle.THIN);
contentWriteCellStyle.setBorderBottom(BorderStyle.THIN);
DataFormatData dataFormatData = new DataFormatData();
dataFormatData.setIndex((short)49);
contentWriteCellStyle.setDataFormatData(dataFormatData);
contentWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);
WriteCellData<?> cellData = context.getFirstCellData();
WriteCellStyle.merge(contentWriteCellStyle, cellData.getOrCreateStyle());
}
}行高设置
import com.alibaba.excel.write.style.row.AbstractRowHeightStyleStrategy;
import org.apache.poi.ss.usermodel.Row;
public class CellRowHeightStyleStrategy extends AbstractRowHeightStyleStrategy {
@Override
protected void setHeadColumnHeight(Row row, int relativeRowIndex) {
//设置主标题行高为17.7
if(relativeRowIndex == 0){
//如果excel需要显示行高为15，那这里就要设置为15*20=300
row.setHeight((short) 3240);
}
}
@Override
protected void setContentColumnHeight(Row row, int relativeRowIndex) {
}
}
列宽度自适应
如果是简单表头，可以使用EasyExcel中的LongestMatchColumnWidthStyleStrategy()来实现。
EasyExcel.write(fileName, LongestMatchColumnWidthData.class)
.registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()).sheet("模板").doWrite(dataLong());
如果是复杂表头，就需要自己来实现，代码如下：
import com.alibaba.excel.enums.CellDataTypeEnum;
import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.metadata.data.CellData;
import com.alibaba.excel.metadata.data.WriteCellData;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.style.column.AbstractColumnWidthStyleStrategy;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.collections.CollectionUtils;
import org.apache.poi.ss.usermodel.Cell;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@Slf4j
public class CellWidthStyleStrategy extends AbstractColumnWidthStyleStrategy {
private Map<Integer, Map<Integer, Integer>> CACHE = new HashMap<>();
@Override
protected void setColumnWidth(WriteSheetHolder writeSheetHolder, List<WriteCellData<?>> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {
Map<Integer, Integer> maxColumnWidthMap = CACHE.get(writeSheetHolder.getSheetNo());
if (maxColumnWidthMap == null) {
maxColumnWidthMap = new HashMap<>();
CACHE.put(writeSheetHolder.getSheetNo(), maxColumnWidthMap);
}
if (isHead) {
if(relativeRowIndex.intValue() == 1){
Integer length = cell.getStringCellValue().getBytes().length;
Integer maxColumnWidth = maxColumnWidthMap.get(cell.getColumnIndex());
if (maxColumnWidth == null || length > maxColumnWidth) {
maxColumnWidthMap.put(cell.getColumnIndex(), length);
writeSheetHolder.getSheet().setColumnWidth(cell.getColumnIndex(), length * 300);
}
}
}else{
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);
}
}
}
}
private Integer dataLength(List<WriteCellData<?>> cellDataList, Cell cell, Boolean isHead) {
if (isHead) {
return cell.getStringCellValue().getBytes().length;
} else {
CellData cellData = cellDataList.get(0);
CellDataTypeEnum type = cellData.getType();
if (type == null) {
return -1;
} else {
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;
}
}
}
}
}写入文件
EasyExcel.write(response.getOutputStream())
.head(head)
.registerWriteHandler(new CellRowHeightStyleStrategy()) //设置行高的策略
.registerWriteHandler(new CellStyleStrategy(Arrays.asList(0,1),new WriteCellStyle(), new WriteCellStyle()))
.registerWriteHandler(new CellWidthStyleStrategy())
.sheet(sheetName)
.doWrite(list);
总结
以上便是EasyExcel解析动态表头及导出的整个过程。
在使用过程中，笔者的感受是，上手难度很低，很适合新手去做简单的表格解析，当然，如果你的需求有复杂的格式，EasyExcel也提供了api，能够很好的满足需要。
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