Apache POI是一个用于读写Microsoft Office文件格式的Java库，可以用来读取或写入Excel文件。

使用步骤

1.导入坐标

<!--alibaba-fastjson-->
<dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>2.0.9.graal</version>
</dependency> 
<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-compress -->
<dependency><groupId>org.apache.commons</groupId><artifactId>commons-compress</artifactId><version>1.26.1</version>
</dependency>
<!-- Excel处理 -->
<dependency><groupId>org.apache.poi</groupId><artifactId>poi-ooxml</artifactId><version>4.1.2</version>
</dependency>

2.封装类

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;import java.io.*;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;public class ExcelHelper {//文件后缀private final static String XLSX = ".xlsx";private final static String XLS = ".xls";/*** json数据导出Excel** @param json     json数据* @param filepath 文件路径* @return true 导出成功*/public static boolean jsonToExcel(String json, String filepath) {try {JSONArray array = JSONArray.parseArray(json);Workbook workbook = new XSSFWorkbook();Sheet sheet = workbook.createSheet("Sheet1");// 创建表头Row header = sheet.createRow(0);JSONObject title = array.getJSONObject(0);for (String s : title.keySet()) {Cell cell = header.createCell(header.getLastCellNum() < 0 ? 0 : header.getLastCellNum());cell.setCellValue(s);}// 填充数据for (int i = 0; i < array.size(); i++) {JSONObject object = array.getJSONObject(i);Row row = sheet.createRow(i + 1);int colNum = 0;for (String key : object.keySet()) {Object value = object.get(key);row.createCell(colNum).setCellValue(String.valueOf(value));colNum++;}}// 导出到文件OutputStream outputStream = new FileOutputStream(filepath);workbook.write(outputStream);workbook.close();return true;} catch (IOException e) {System.out.println(e.getMessage());return false;}}/*** Excel数据读取成json** @param filepath 文件路径* @return json数据*/public static JSONArray excelToJsonArray(String filepath) throws IOException, InvalidFormatException {File file = new File(filepath);String flieName = file.getName();Workbook book = null;Sheet sheet = null;if (flieName.endsWith(XLSX)) {book = new XSSFWorkbook(file);sheet = book.getSheetAt(0);}if (flieName.endsWith(XLS)) {POIFSFileSystem poifsFileSystem = new POIFSFileSystem(new FileInputStream(file));book = new HSSFWorkbook(poifsFileSystem);sheet = book.getSheetAt(0);}if (sheet != null) {return readSheet(sheet, book);}return new JSONArray();}/*** 读取Excel** @param sheet 工作表* @param book  工作簿* @return json数据*/public static JSONArray readSheet(Sheet sheet, Workbook book) throws IOException {int rowStart = sheet.getFirstRowNum(); // 首行下标int rowEnd = sheet.getLastRowNum();    // 尾行下标// 如果首行与尾行相同，表明只有一行，直接返回空数组if (rowStart == rowEnd) {book.close();return new JSONArray();}// 获取第一行JSON对象键Row firstRow = sheet.getRow(rowStart);int cellStart = firstRow.getFirstCellNum();int cellEnd = firstRow.getLastCellNum();Map<Integer, String> keyMap = new HashMap<Integer, String>();for (int j = cellStart; j < cellEnd; j++) {keyMap.put(j, getValue(firstRow.getCell(j), rowStart, j, book, true));}// 获取每行JSON对象的值JSONArray array = new JSONArray();for (int i = rowStart + 1; i <= rowEnd; i++) {Row eachRow = sheet.getRow(i);JSONObject obj = new JSONObject();StringBuffer sb = new StringBuffer();for (int k = cellStart; k < cellEnd; k++) {if (eachRow != null) {String val = getValue(eachRow.getCell(k), i, k, book, false);sb.append(val);        // 所有数据添加到里面，用于判断该行是否为空obj.put(keyMap.get(k), val);}}if (!sb.toString().isEmpty()) {array.add(obj);}}book.close();return array;}/*** 获取每个单元格的数据** @param cell   单元格对象* @param rowNum 第几行* @param index  该行第几个* @param book   主要用于关闭流* @param isKey  是否为键：true-是，false-不是。 如果解析Json键，值为空时报错；如果不是Json键，值为空不报错*/public static String getValue(Cell cell, int rowNum, int index, Workbook book, boolean isKey) throws IOException {// 空白或空if (cell == null || cell.getCellTypeEnum() == CellType.BLANK) {if (isKey) {book.close();throw new NullPointerException(String.format("the key on row %s index %s is null ", ++rowNum, ++index));} else {return "";}}// 0. 数字 类型if (cell.getCellTypeEnum() == CellType.NUMERIC) {if (HSSFDateUtil.isCellDateFormatted(cell)) {Date date = cell.getDateCellValue();DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");return df.format(date);}String val = cell.getNumericCellValue() + "";val = val.toUpperCase();if (val.contains("E")) {val = val.split("E")[0].replace(".", "");}return val;}// 1. String类型if (cell.getCellTypeEnum() == CellType.STRING) {String val = cell.getStringCellValue();if (val == null || val.trim().isEmpty()) {if (book != null) {book.close();}return "";}return val.trim();}// 2. 公式 CELL_TYPE_FORMULAif (cell.getCellTypeEnum() == CellType.FORMULA) {return cell.getStringCellValue();}// 4. 布尔值 CELL_TYPE_BOOLEANif (cell.getCellTypeEnum() == CellType.BOOLEAN) {return cell.getBooleanCellValue() + "";}// 5.	错误 CELL_TYPE_ERRORreturn "";}
}

3.使用方式

public static void main(String[] args) throws IOException, InvalidFormatException {//导出Excelvar json = "[{\"name\":\"张三\",\"age\":\"18\"},{\"name\":\"李四\",\"age\":\"19\"}]";System.out.println(jsonToExcel(json, "D:\\test.xlsx"));//读取ExcelSystem.out.println(excelToJsonArray("D:\\test.xlsx"));
}