208 lines
7.5 KiB
Markdown
208 lines
7.5 KiB
Markdown
# Excel快速导出
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## 功能介绍
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- 在对应实现类上加上自定义注解`@Excel`后,在编写web接口是调用ExcelUtil.exportExcel即可实现对应实体Excel的快速导出
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## 实现原理
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- 主要使用到Java反射机制,获取到目标实体的Class对象后通过java发射获取到每个字段,并且获取到对应字段上的@Excel注解,将注解中的数据记录下来作为Excel中的表头。再通过java反射获取到对应的数据并做好与标表头的映射关系，最终使用ease-excel实现Excel的渲染
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## 代码展示
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```java
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package cn.odliken.security.utils;
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import cn.odliken.admin.api.entity.DictData;
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import cn.odliken.admin.api.fegin.DictDataService;
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import cn.odliken.common.core.constant.ResultConstant;
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import cn.odliken.common.core.constant.SecurityConstants;
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import cn.odliken.common.core.exception.CustomException;
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import cn.odliken.common.core.result.Result;
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import cn.odliken.common.core.utils.DateUtils;
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import cn.odliken.common.core.utils.SpringContextHolder;
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import cn.odliken.common.core.utils.StringUtils;
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import cn.odliken.common.core.utils.reflect.ReflectUtils;
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import cn.odliken.security.annotation.Excel;
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import cn.odliken.security.annotation.Excels;
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import com.alibaba.excel.EasyExcel;
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import com.alibaba.excel.support.ExcelTypeEnum;
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import javax.servlet.http.HttpServletResponse;
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import java.io.IOException;
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import java.lang.reflect.Field;
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import java.util.*;
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import java.util.stream.Collectors;
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/**
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* @author Clay
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* @date 2022/12/19
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*/
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public class ExcelUtil {
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public static List<ExcelAssist> assistList = new ArrayList<>();
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public static Map<String,Map<String,DictData>> dictDataMap;
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private static DictDataService getBean() {
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return SpringContextHolder.getBean(DictDataService.class);
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}
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/**
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* 获取到数据列表
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*
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* @param list
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* @return
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*/
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private static List<List<Object>> getDataList(List<?> list) {
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return list.stream().map(object ->
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assistList.stream().map(assist -> {
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Field field = assist.getField();
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Excel excel = assist.getExcel();
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Object value = null;
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if (StringUtils.isEmpty(assist.getObjectFieldName())) {
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value = getData(object, excel, field);
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} else {
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Object sunValue = null;
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try {
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sunValue = ReflectUtils.invokeGetter(object, assist.getObjectFieldName());
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} catch (Exception e) {
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return null;
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}
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if (null != sunValue) {
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value = getData(object, excel, field);
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}
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}
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return value;
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}).collect(Collectors.toList())
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).collect(Collectors.toList());
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}
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/**
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* 获取到对象中的数据
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*
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* @param object
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* @param excel
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* @param field
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* @return
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*/
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private static Object getData(Object object, Excel excel, Field field) {
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try {
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Object objectValue = ReflectUtils.invokeGetter(object, field.getName());
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if (objectValue instanceof Date) {
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objectValue = DateUtils.parseDateToStr(excel.dateFormat(), (Date) objectValue);
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}
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String dictType = excel.dictType();
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if (StringUtils.isNotEmpty(dictType)){
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Map<String,DictData> dictMap = dictDataMap.get(dictType);
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if (null != dictMap){
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DictData dictData = dictMap.get(objectValue.toString());
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if (null!= dictData){
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objectValue = dictData.getDictLabel();
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}
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}
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}
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return objectValue;
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} catch (Exception e) {
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return null;
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}
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}
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/**
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* 初始化header数据
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*
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* @param clazz
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* @param assist
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*/
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private static void initHeader(Class<?> clazz, ExcelAssist assist) {
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for (Field field : clazz.getDeclaredFields()) {
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Excel excel = field.getAnnotation(Excel.class);
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if (null != excel) {
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assistList.add(new ExcelAssist(field, excel, assist));
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} else {
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Excels excels = field.getAnnotation(Excels.class);
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if (excels == null) {
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continue;
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}
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Class<?> objectValue = field.getType();
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if (clazz == objectValue) {
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throw new CustomException("不允许嵌套对象导出Excel");
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}
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ExcelAssist excelAssist = new ExcelAssist(field, excels);
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initHeader(objectValue, excelAssist);
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}
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}
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}
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public static void exportExcel(List<?> list, Class<?> clazz) {
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exportExcel(list, clazz, null);
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}
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/**
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* 导出数据Excel
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*
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* @param list
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* @param clazz
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* @param sheetName
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*/
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public static void exportExcel(List<?> list, Class<?> clazz, String sheetName) {
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Set<String> dictList = new HashSet<>();
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initHeader(clazz, null);
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List<List<String>> headerList = new ArrayList<>(assistList.size());
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assistList = assistList.stream().sorted(Comparator.comparing(ExcelAssist::getOrder))
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.peek(assist -> headerList.add(Collections.singletonList(assist.getExcel().value())))
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.peek(assist -> {
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String dictType = assist.getExcel().dictType();
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if (StringUtils.isNotEmpty(dictType)) {
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dictList.add(dictType);
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}
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})
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.collect(Collectors.toList());
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if (dictList.size() > 0) {
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getDictData(new ArrayList<>(dictList));
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}
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List<List<Object>> dataList = getDataList(list);
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try {
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sheetName = StringUtils.isEmpty(sheetName) ? "sheet" : sheetName;
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HttpServletResponse response = getResponse(sheetName);
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EasyExcel.write(response.getOutputStream())
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.head(headerList)
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.excelType(ExcelTypeEnum.XLSX)
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.sheet(StringUtils.isEmpty(sheetName) ? "sheet" : sheetName)
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.doWrite(dataList);
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} catch (IOException e) {
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throw new CustomException("Excel导出失败!");
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}
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}
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private static HttpServletResponse getResponse(String sheetName){
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HttpServletResponse response = SecurityUtils.getResponse();
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response.setCharacterEncoding("utf-8");
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response.setContentType("multipart/form-data");
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response.setHeader("Content-Disposition" ,
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"attachment;fileName=" + sheetName + UUID.randomUUID() + ".xlsx");
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return response;
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}
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private static void getDictData(List<String> dictList) {
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DictDataService dictDataService = getBean();
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Result<Map<String, Map<String,DictData>>> result = dictDataService.searchDictDataCacheKeys(dictList, SecurityConstants.FROM_IN);
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System.out.println(result);
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if (result.getCode() == ResultConstant.SUCCESS_CODE){
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dictDataMap = result.getData();
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}
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}
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}
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```
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## 使用demo
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```java
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@ApiOperation("导出excel数据")
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@GetMapping("/export")
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@PreAuthorize("@ss.hasPermission('code:goods:export')")
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public void export(DemoGoodsQuery query){
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List<DemoGoodsVo> list = demoGoodsService.exportDemoGoodsList(query);
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ExcelUtil.exportExcel(list,DemoGoodsVo.class);
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}
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```
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