1. Excel处理基础知识

1.1 为什么需要在应用中处理Excel文件？

在企业应用开发中，Excel文件处理是一个非常常见的需求，主要用于以下场景：

• 数据导入：允许用户通过Excel上传批量数据到系统
• 数据导出：将系统数据导出为Excel供用户下载分析
• 报表生成：生成复杂的报表并格式化为Excel
• 数据交换：作为不同系统间交换数据的媒介
• 批量数据处理：处理大量结构化数据

1.2 Java中的Excel处理库介绍

Java中处理Excel文件的主要库有以下几种：

1.2.1 Apache POI

Apache POI是Java中使用最广泛的Excel处理库，提供了全面的API来创建、读取和修改Office文档。

优点：

• 功能全面，支持Excel所有功能
• 支持.xls (HSSF - Excel 97-2003)和.xlsx (XSSF - Excel 2007+)格式
• 社区活跃，文档丰富
• 支持公式计算、图表、合并单元格等高级功能

缺点：

• API相对复杂
• 处理大文件时内存消耗大（尤其是XSSF）

1.2.2 EasyExcel

EasyExcel是阿里巴巴开源的Excel处理库，基于POI，但做了大量优化。

优点：

• 内存占用低，使用SAX模式读取，避免OOM
• API简单易用，注解驱动
• 读写速度快
• 适合处理大型Excel文件

缺点：

• 功能不如POI全面
• 灵活性相对较低

1.2.3 JExcel

JExcel是另一个处理Excel的Java库。

优点：

• API较简单
• 速度较快

缺点：

• 仅支持旧版Excel (.xls)格式
• 不再积极维护
• 功能有限

1.2.4 Apache POI SXSSF

SXSSF是POI提供的一种流式处理模式，专为处理大型Excel文件设计。

优点：

• 大大降低内存占用
• 适合生成大型Excel文件

缺点：

• 仅支持写入操作，不支持读取
• 功能比XSSF受限

1.3 Spring Boot中集成Excel处理

Spring Boot本身不提供Excel处理功能，但可以轻松集成上述各种Excel处理库。本指南将主要介绍：

1. 如何在Spring Boot项目中集成Apache POI和EasyExcel
2. 如何实现Excel导入导出的常见功能
3. 如何处理常见问题和优化性能

2. 在Spring Boot中集成Excel处理库

2.1 集成Apache POI

2.1.1 添加依赖

在pom.xml文件中添加以下依赖：

<dependency><groupId>org.apache.poi</groupId><artifactId>poi</artifactId><version>5.2.3</version>
</dependency>
<dependency><groupId>org.apache.poi</groupId><artifactId>poi-ooxml</artifactId><version>5.2.3</version>
</dependency>

如果使用Gradle，在build.gradle中添加：

implementation 'org.apache.poi:poi:5.2.3'
implementation 'org.apache.poi:poi-ooxml:5.2.3'

2.1.2 创建基本配置类

创建一个配置类来处理Excel相关的配置：

package com.example.excel.config;import org.apache.poi.ss.usermodel.WorkbookFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.multipart.MultipartResolver;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;@Configuration
public class ExcelConfig {@Beanpublic MultipartResolver multipartResolver() {CommonsMultipartResolver resolver = new CommonsMultipartResolver();resolver.setMaxUploadSize(10485760); // 设置上传文件最大为10MBreturn resolver;}
}

2.2 集成EasyExcel

2.2.1 添加依赖

在pom.xml文件中添加以下依赖：

<dependency><groupId>com.alibaba</groupId><artifactId>easyexcel</artifactId><version>3.2.1</version>
</dependency>

如果使用Gradle，在build.gradle中添加：

implementation 'com.alibaba:easyexcel:3.2.1'

2.2.2 创建配置类

package com.example.excel.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.multipart.MultipartResolver;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;@Configuration
public class EasyExcelConfig {@Beanpublic MultipartResolver multipartResolver() {CommonsMultipartResolver resolver = new CommonsMultipartResolver();resolver.setMaxUploadSize(10485760); // 设置上传文件最大为10MBreturn resolver;}
}

3. 使用Apache POI读取Excel文件

3.1 创建数据模型

首先，创建一个模型类来映射Excel中的数据：

package com.example.excel.model;import lombok.Data;@Data
public class User {private Long id;private String name;private Integer age;private String email;private String department;
}

3.2 创建Excel读取服务

创建一个服务类来处理Excel文件读取：

package com.example.excel.service;import com.example.excel.model.User;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;@Service
public class ExcelService {public List<User> readUsersFromExcel(MultipartFile file) throws IOException {List<User> userList = new ArrayList<>();// 获取工作簿try (InputStream inputStream = file.getInputStream()) {Workbook workbook = WorkbookFactory.create(inputStream);// 获取第一个工作表Sheet sheet = workbook.getSheetAt(0);// 跳过标题行Iterator<Row> rowIterator = sheet.rowIterator();if (rowIterator.hasNext()) {rowIterator.next(); // 跳过标题行}// 遍历数据行while (rowIterator.hasNext()) {Row row = rowIterator.next();User user = new User();// 读取单元格数据user.setId((long) row.getCell(0, Row.MissingCellPolicy.CREATE_NULL_AS_BLANK).getNumericCellValue());user.setName(getCellValueAsString(row.getCell(1)));user.setAge((int) row.getCell(2, Row.MissingCellPolicy.CREATE_NULL_AS_BLANK).getNumericCellValue());user.setEmail(getCellValueAsString(row.getCell(3)));user.setDepartment(getCellValueAsString(row.getCell(4)));userList.add(user);}workbook.close();}return userList;}// 获取单元格的字符串值private String getCellValueAsString(Cell cell) {if (cell == null) {return "";}switch (cell.getCellType()) {case STRING:return cell.getStringCellValue();case NUMERIC:if (DateUtil.isCellDateFormatted(cell)) {return cell.getDateCellValue().toString();} else {return String.valueOf((int) cell.getNumericCellValue());}case BOOLEAN:return String.valueOf(cell.getBooleanCellValue());case FORMULA:return cell.getCellFormula();default:return "";}}
}

3.3 创建Controller处理Excel上传

创建一个Controller来处理Excel文件上传：

package com.example.excel.controller;import com.example.excel.model.User;
import com.example.excel.service.ExcelService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;import java.io.IOException;
import java.util.List;@RestController
@RequestMapping("/api/excel")
public class ExcelController {@Autowiredprivate ExcelService excelService;@PostMapping("/upload")public ResponseEntity<List<User>> uploadExcel(@RequestParam("file") MultipartFile file) {try {List<User> users = excelService.readUsersFromExcel(file);return ResponseEntity.ok(users);} catch (IOException e) {e.printStackTrace();return ResponseEntity.badRequest().build();}}
}

3.4 创建HTML上传页面

在src/main/resources/templates目录下创建upload.html：

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head><meta charset="UTF-8"><title>Excel上传</title><link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
</head>
<body><div class="container mt-5"><div class="card"><div class="card-header"><h3>上传Excel文件</h3></div><div class="card-body"><form id="uploadForm" enctype="multipart/form-data"><div class="form-group"><label for="file">选择Excel文件:</label><input type="file" class="form-control-file" id="file" name="file" accept=".xls,.xlsx"></div><button type="button" class="btn btn-primary" onclick="uploadExcel()">上传</button></form><div class="mt-4"><h4>上传结果:</h4><div id="resultContainer"></div></div></div></div></div><script src="https://code.jquery.com/jquery-3.5.1.min.js"></script><script>function uploadExcel() {var formData = new FormData(document.getElementById('uploadForm'));$.ajax({url: '/api/excel/upload',type: 'POST',data: formData,processData: false,contentType: false,success: function(response) {var resultHtml = '<table class="table table-striped">' +'<thead><tr><th>ID</th><th>姓名</th><th>年龄</th><th>邮箱</th><th>部门</th></tr></thead>' +'<tbody>';for (var i = 0; i < response.length; i++) {var user = response[i];resultHtml += '<tr>' +'<td>' + user.id + '</td>' +'<td>' + user.name + '</td>' +'<td>' + user.age + '</td>' +'<td>' + user.email + '</td>' +'<td>' + user.department + '</td>' +'</tr>';}resultHtml += '</tbody></table>';$('#resultContainer').html(resultHtml);},error: function(error) {$('#resultContainer').html('<div class="alert alert-danger">上传失败: ' + error.responseText + '</div>');}});}</script>
</body>
</html>

3.5 处理更复杂的Excel结构

在实际应用中，Excel结构可能更复杂，如多个工作表、合并单元格、公式等。以下是处理这些情况的示例：

public List<Department> readComplexExcel(MultipartFile file) throws IOException {List<Department> departments = new ArrayList<>();try (InputStream inputStream = file.getInputStream()) {Workbook workbook = WorkbookFactory.create(inputStream);// 读取部门信息（第一个工作表）Sheet departmentSheet = workbook.getSheetAt(0);for (int i = 1; i <= departmentSheet.getLastRowNum(); i++) {Row row = departmentSheet.getRow(i);if (row == null) continue;Department department = new Department();department.setId((long) row.getCell(0).getNumericCellValue());department.setName(row.getCell(1).getStringCellValue());department.setManager(row.getCell(2).getStringCellValue());department.setEmployees(new ArrayList<>());departments.add(department);}// 读取员工信息（第二个工作表）Sheet employeeSheet = workbook.getSheetAt(1);for (int i = 1; i <= employeeSheet.getLastRowNum(); i++) {Row row = employeeSheet.getRow(i);if (row == null) continue;User employee = new User();employee.setId((long) row.getCell(0).getNumericCellValue());employee.setName(row.getCell(1).getStringCellValue());employee.setAge((int) row.getCell(2).getNumericCellValue());employee.setEmail(row.getCell(3).getStringCellValue());// 获取部门ID并关联到相应部门long departmentId = (long) row.getCell(4).getNumericCellValue();for (Department dept : departments) {if (dept.getId() == departmentId) {dept.getEmployees().add(employee);break;}}}workbook.close();}return departments;
}

4. 使用Apache POI创建和导出Excel文件

4.1 创建基本Excel文件

以下是一个创建简单Excel文件的示例：

package com.example.excel.service;import com.example.excel.model.User;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.stereotype.Service;import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.List;@Service
public class ExcelExportService {public ByteArrayInputStream exportUsersToExcel(List<User> users) throws IOException {try (Workbook workbook = new XSSFWorkbook()) {// 创建工作表Sheet sheet = workbook.createSheet("用户数据");// 创建表头样式Font headerFont = workbook.createFont();headerFont.setBold(true);headerFont.setColor(IndexedColors.BLUE.getIndex());CellStyle headerCellStyle = workbook.createCellStyle();headerCellStyle.setFont(headerFont);headerCellStyle.setFillForegroundColor(IndexedColors.LIGHT_YELLOW.getIndex());headerCellStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);headerCellStyle.setBorderBottom(BorderStyle.THIN);headerCellStyle.setBorderTop(BorderStyle.THIN);headerCellStyle.setBorderRight(BorderStyle.THIN);headerCellStyle.setBorderLeft(BorderStyle.THIN);// 创建表头行Row headerRow = sheet.createRow(0);// 创建表头单元格Cell cell0 = headerRow.createCell(0);cell0.setCellValue("ID");cell0.setCellStyle(headerCellStyle);Cell cell1 = headerRow.createCell(1);cell1.setCellValue("姓名");cell1.setCellStyle(headerCellStyle);Cell cell2 = headerRow.createCell(2);cell2.setCellValue("年龄");cell2.setCellStyle(headerCellStyle);Cell cell3 = headerRow.createCell(3);cell3.setCellValue("邮箱");cell3.setCellStyle(headerCellStyle);Cell cell4 = headerRow.createCell(4);cell4.setCellValue("部门");cell4.setCellStyle(headerCellStyle);// 设置数据单元格样式CellStyle dataCellStyle = workbook.createCellStyle();dataCellStyle.setBorderBottom(BorderStyle.THIN);dataCellStyle.setBorderTop(BorderStyle.THIN);dataCellStyle.setBorderRight(BorderStyle.THIN);dataCellStyle.setBorderLeft(BorderStyle.THIN);// 创建数据行int rowIdx = 1;for (User user : users) {Row row = sheet.createRow(rowIdx++);Cell idCell = row.createCell(0);idCell.setCellValue(user.getId());idCell.setCellStyle(dataCellStyle);Cell nameCell = row.createCell(1);nameCell.setCellValue(user.getName());nameCell.setCellStyle(dataCellStyle);Cell ageCell = row.createCell(2);ageCell.setCellValue(user.getAge());ageCell.setCellStyle(dataCellStyle);Cell emailCell = row.createCell(3);emailCell.setCellValue(user.getEmail());emailCell.setCellStyle(dataCellStyle);Cell deptCell = row.createCell(4);deptCell.setCellValue(user.getDepartment());deptCell.setCellStyle(dataCellStyle);}// 自动调整列宽for (int i = 0; i < 5; i++) {sheet.autoSizeColumn(i);}// 写入ByteArrayOutputStreamByteArrayOutputStream outputStream = new ByteArrayOutputStream();workbook.write(outputStream);return new ByteArrayInputStream(outputStream.toByteArray());}}
}

4.2 创建导出控制器

package com.example.excel.controller;import com.example.excel.model.User;
import com.example.excel.service.ExcelExportService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;@RestController
@RequestMapping("/api/excel")
public class ExcelExportController {@Autowiredprivate ExcelExportService excelExportService;@GetMapping("/export")public ResponseEntity<InputStreamResource> exportUsers() throws IOException {// 生成示例数据List<User> users = getTestUsers();// 生成Excel文件ByteArrayInputStream in = excelExportService.exportUsersToExcel(users);// 设置HTTP头HttpHeaders headers = new HttpHeaders();headers.add("Content-Disposition", "attachment; filename=users.xlsx");// 返回Excel文件return ResponseEntity.ok().headers(headers).contentType(MediaType.parseMediaType("application/vnd.ms-excel")).body(new InputStreamResource(in));}// 生成测试用户数据private List<User> getTestUsers() {List<User> users = new ArrayList<>();User user1 = new User();user1.setId(1L);user1.setName("张三");user1.setAge(28);user1.setEmail("zhangsan@example.com");user1.setDepartment("研发部");users.add(user1);User user2 = new User();user2.setId(2L);user2.setName("李四");user2.setAge(32);user2.setEmail("lisi@example.com");user2.setDepartment("市场部");users.add(user2);User user3 = new User();user3.setId(3L);user3.setName("王五");user3.setAge(45);user3.setEmail("wangwu@example.com");user3.setDepartment("行政部");users.add(user3);User user4 = new User();user4.setId(4L);user4.setName("赵六");user4.setAge(36);user4.setEmail("zhaoliu@example.com");user4.setDepartment("财务部");users.add(user4);User user5 = new User();user5.setId(5L);user5.setName("钱七");user5.setAge(29);user5.setEmail("qianqi@example.com");user5.setDepartment("人力资源部");users.add(user5);return users;}
}

4.3 创建导出页面

在src/main/resources/templates目录下创建export.html：

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head><meta charset="UTF-8"><title>Excel导出</title><link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
</head>
<body><div class="container mt-5"><div class="card"><div class="card-header"><h3>导出Excel文件</h3></div><div class="card-body"><p>点击下面的按钮导出用户数据到Excel文件：</p><a href="/api/excel/export" class="btn btn-primary">导出用户数据</a></div></div></div>
</body>
</html>

4.4 创建复杂的Excel文件

以下是一个创建更复杂Excel文件的示例，包含多个工作表、合并单元格、公式等：

public ByteArrayInputStream exportComplexExcel(List<Department> departments) throws IOException {try (Workbook workbook = new XSSFWorkbook()) {// 创建字体和样式Font headerFont = workbook.createFont();headerFont.setBold(true);headerFont.setFontHeightInPoints((short) 14);CellStyle headerStyle = workbook.createCellStyle();headerStyle.setFont(headerFont);headerStyle.setFillForegroundColor(IndexedColors.LIGHT_BLUE.getIndex());headerStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);headerStyle.setAlignment(HorizontalAlignment.CENTER);CellStyle titleStyle = workbook.createCellStyle();Font titleFont = workbook.createFont();titleFont.setBold(true);titleFont.setFontHeightInPoints((short) 16);titleStyle.setFont(titleFont);titleStyle.setAlignment(HorizontalAlignment.CENTER);// 创建汇总表Sheet summarySheet = workbook.createSheet("部门汇总");// 创建标题行Row titleRow = summarySheet.createRow(0);Cell titleCell = titleRow.createCell(0);titleCell.setCellValue("公司部门人员统计");titleCell.setCellStyle(titleStyle);// 合并标题单元格summarySheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 3));// 创建表头Row headerRow = summarySheet.createRow(1);String[] headers = {"部门ID", "部门名称", "部门经理", "员工数量"};for (int i = 0; i < headers.length; i++) {Cell cell = headerRow.createCell(i);cell.setCellValue(headers[i]);cell.setCellStyle(headerStyle);}// 填充部门数据int rowIdx = 2;int totalEmployees = 0;for (Department dept : departments) {Row row = summarySheet.createRow(rowIdx++);row.createCell(0).setCellValue(dept.getId());row.createCell(1).setCellValue(dept.getName());row.createCell(2).setCellValue(dept.getManager());row.createCell(3).setCellValue(dept.getEmployees().size());totalEmployees += dept.getEmployees().size();// 为每个部门创建单独的工作表Sheet deptSheet = workbook.createSheet(dept.getName());// 创建部门表头Row deptHeaderRow = deptSheet.createRow(0);Cell deptTitleCell = deptHeaderRow.createCell(0);deptTitleCell.setCellValue(dept.getName() + " - 员工列表");deptTitleCell.setCellStyle(titleStyle);deptSheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 4));// 员工表头Row empHeaderRow = deptSheet.createRow(1);String[] empHeaders = {"员工ID", "姓名", "年龄", "邮箱", "入职年限"};for (int i = 0; i < empHeaders.length; i++) {Cell cell = empHeaderRow.createCell(i);cell.setCellValue(empHeaders[i]);cell.setCellStyle(headerStyle);}// 填充员工数据int empRowIdx = 2;for (User emp : dept.getEmployees()) {Row empRow = deptSheet.createRow(empRowIdx++);empRow.createCell(0).setCellValue(emp.getId());empRow.createCell(1).setCellValue(emp.getName());empRow.createCell(2).setCellValue(emp.getAge());empRow.createCell(3).setCellValue(emp.getEmail());// 使用公式计算入职年限（假设年龄减去25）Cell tenureCell = empRow.createCell(4);tenureCell.setCellFormula("C" + empRowIdx + "-25");}// 自动调整列宽for (int i = 0; i < 5; i++) {deptSheet.autoSizeColumn(i);}}// 创建总计行Row totalRow = summarySheet.createRow(rowIdx);Cell totalLabelCell = totalRow.createCell(0);totalLabelCell.setCellValue("总计");totalLabelCell.setCellStyle(headerStyle);// 合并总计标签单元格summarySheet.addMergedRegion(new CellRangeAddress(rowIdx, rowIdx, 0, 2));Cell totalValueCell = totalRow.createCell(3);totalValueCell.setCellValue(totalEmployees);totalValueCell.setCellStyle(headerStyle);// 自动调整列宽for (int i = 0; i < 4; i++) {summarySheet.autoSizeColumn(i);}// 添加图表XSSFSheet chartSheet = (XSSFSheet) workbook.createSheet("部门统计图");// 复制部门数据到图表数据表Row chartHeaderRow = chartSheet.createRow(0);chartHeaderRow.createCell(0).setCellValue("部门");chartHeaderRow.createCell(1).setCellValue("员工数");int chartRowIdx = 1;for (Department dept : departments) {Row row = chartSheet.createRow(chartRowIdx++);row.createCell(0).setCellValue(dept.getName());row.createCell(1).setCellValue(dept.getEmployees().size());}// 创建图表和数据序列XSSFDrawing drawing = chartSheet.createDrawingPatriarch();XSSFClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 4, 0, 15, 15);XSSFChart chart = drawing.createChart(anchor);chart.setTitleText("部门人员分布");chart.setTitleOverlay(false);XDDFChartLegend legend = chart.getOrAddLegend();legend.setPosition(LegendPosition.RIGHT);// X轴和Y轴XDDFCategoryAxis bottomAxis = chart.createCategoryAxis(AxisPosition.BOTTOM);bottomAxis.setTitle("部门");XDDFValueAxis leftAxis = chart.createValueAxis(AxisPosition.LEFT);leftAxis.setTitle("员工数");// 创建数据源XDDFDataSource<String> departments = XDDFDataSourcesFactory.fromStringCellRange(chartSheet, new CellRangeAddress(1, chartRowIdx - 1, 0, 0));XDDFNumericalDataSource<Double> values = XDDFDataSourcesFactory.fromNumericCellRange(chartSheet, new CellRangeAddress(1, chartRowIdx - 1, 1, 1));// 创建柱状图XDDFBarChartData barChart = (XDDFBarChartData) chart.createData(ChartTypes.BAR, bottomAxis, leftAxis);barChart.setVaryColors(true);XDDFBarChartData.Series series = (XDDFBarChartData.Series) barChart.addSeries(departments, values);series.setTitle("员工数", null);chart.plot(barChart);// 写入ByteArrayOutputStreamByteArrayOutputStream outputStream = new ByteArrayOutputStream();workbook.write(outputStream);return new ByteArrayInputStream(outputStream.toByteArray());}
}

注意：上面的图表代码需要添加以下依赖：

<dependency><groupId>org.apache.poi</groupId><artifactId>poi-ooxml-full</artifactId><version>5.2.3</version>
</dependency>

4.5 使用模板导出Excel

在某些场景下，我们需要基于预定义的Excel模板生成文件，以下是一个示例：

public ByteArrayInputStream exportFromTemplate(List<User> users) throws IOException {// 加载模板文件try (InputStream templateStream = getClass().getResourceAsStream("/templates/user_template.xlsx");Workbook workbook = WorkbookFactory.create(templateStream)) {Sheet sheet = workbook.getSheetAt(0);// 从第二行开始填充数据（第一行是表头）int rowIdx = 1;for (User user : users) {Row row = sheet.createRow(rowIdx++);row.createCell(0).setCellValue(user.getId());row.createCell(1).setCellValue(user.getName());row.createCell(2).setCellValue(user.getAge());row.createCell(3).setCellValue(user.getEmail());row.createCell(4).setCellValue(user.getDepartment());}// 更新模板中的日期单元格（假设在A1位置）Row headerRow = sheet.getRow(0);if (headerRow.getCell(6) != null) {Cell dateCell = headerRow.getCell(6);dateCell.setCellValue(new Date());}// 自动调整列宽for (int i = 0; i < 5; i++) {sheet.autoSizeColumn(i);}// 写入ByteArrayOutputStreamByteArrayOutputStream outputStream = new ByteArrayOutputStream();workbook.write(outputStream);return new ByteArrayInputStream(outputStream.toByteArray());}
}

5. 使用EasyExcel处理Excel文件

EasyExcel是阿里巴巴开源的基于POI的Excel处理工具，相比原生POI，它提供了更简洁的API，并且在处理大文件时有明显的性能优势。

5.1 使用EasyExcel读取Excel

5.1.1 创建数据模型

使用EasyExcel时，通常使用注解来映射Excel列：

package com.example.excel.model;import com.alibaba.excel.annotation.ExcelProperty;
import com.alibaba.excel.annotation.format.DateTimeFormat;
import lombok.Data;import java.util.Date;@Data
public class Employee {@ExcelProperty("员工ID")private Long id;@ExcelProperty("姓名")private String name;@ExcelProperty("年龄")private Integer age;@ExcelProperty("邮箱")private String email;@ExcelProperty("部门")private String department;@ExcelProperty("入职日期")@DateTimeFormat("yyyy-MM-dd")private Date hireDate;@ExcelProperty("薪资")private Double salary;
}

5.1.2 创建读取监听器

EasyExcel采用事件模式读取Excel，需要创建一个监听器来处理读取的数据：

package com.example.excel.listener;import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.example.excel.model.Employee;
import lombok.extern.slf4j.Slf4j;import java.util.ArrayList;
import java.util.List;@Slf4j
public class EmployeeReadListener extends AnalysisEventListener<Employee> {/*** 用于暂存读取的数据*/private List<Employee> employeeList = new ArrayList<>();/*** 每读取一行数据就会调用一次invoke方法*/@Overridepublic void invoke(Employee employee, AnalysisContext context) {log.info("读取到一条数据: {}", employee);employeeList.add(employee);// 达到BATCH_COUNT时，需要存储一次数据库，防止数据几万条数据在内存，容易OOMif (employeeList.size() >= 5000) {saveData();// 清理内存employeeList.clear();}}/*** 所有数据解析完成后调用此方法*/@Overridepublic void doAfterAllAnalysed(AnalysisContext context) {// 确保最后一批数据被保存saveData();log.info("所有数据解析完成！");}/*** 保存数据，这里只是打印，实际应用中可以将数据存入数据库*/private void saveData() {log.info("{}条数据，开始保存数据库！", employeeList.size());// 这里可以调用持久层完成数据入库log.info("存储数据库成功！");}/*** 获取读取到的数据*/public List<Employee> getEmployeeList() {return employeeList;}
}

5.1.3 创建Excel读取服务

package com.example.excel.service;import com.alibaba.excel.EasyExcel;
import com.example.excel.listener.EmployeeReadListener;
import com.example.excel.model.Employee;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;import java.io.IOException;
import java.util.List;@Slf4j
@Service
public class EasyExcelService {public List<Employee> readEmployeeData(MultipartFile file) throws IOException {EmployeeReadListener listener = new EmployeeReadListener();EasyExcel.read(file.getInputStream(), Employee.class, listener).sheet().doRead();return listener.getEmployeeList();}
}

5.1.4 创建Controller

package com.example.excel.controller;import com.example.excel.model.Employee;
import com.example.excel.service.EasyExcelService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;import java.io.IOException;
import java.util.List;@Slf4j
@RestController
@RequestMapping("/api/easyexcel")
public class EasyExcelController {@Autowiredprivate EasyExcelService easyExcelService;@PostMapping("/upload")public ResponseEntity<List<Employee>> uploadExcel(@RequestParam("file") MultipartFile file) {try {List<Employee> employees = easyExcelService.readEmployeeData(file);return ResponseEntity.ok(employees);} catch (IOException e) {log.error("Excel读取失败", e);return ResponseEntity.badRequest().build();}}
}

5.2 使用EasyExcel导出Excel

5.2.1 简单导出示例

package com.example.excel.service;import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.write.style.column.LongestMatchColumnWidthStyleStrategy;
import com.example.excel.model.Employee;
import org.springframework.stereotype.Service;import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;@Service
public class EasyExcelExportService {/*** 导出员工数据到Excel文件*/public void exportEmployees(List<Employee> employees, OutputStream outputStream) {EasyExcel.write(outputStream, Employee.class).registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())  // 自动调整列宽.sheet("员工数据").doWrite(employees);}/*** 导出员工数据到指定文件*/public void exportEmployeesToFile(List<Employee> employees, String fileName) throws IOException {// 确保目录存在File file = new File(fileName);if (!file.getParentFile().exists()) {file.getParentFile().mkdirs();}EasyExcel.write(fileName, Employee.class).registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()).sheet("员工数据").doWrite(employees);}/*** 导出多个Sheet的Excel*/public void exportMultipleSheets(List<List<Employee>> departmentEmployees, List<String> sheetNames, OutputStream outputStream) {// 创建ExcelWritertry (var excelWriter = EasyExcel.write(outputStream, Employee.class).registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()).build()) {// 同一个对象多个Sheet写入for (int i = 0; i < departmentEmployees.size(); i++) {// 获取Sheet名称String sheetName = i < sheetNames.size() ? sheetNames.get(i) : "Sheet" + (i + 1);// 创建新的Sheetvar writeSheet = EasyExcel.writerSheet(i, sheetName).build();// 写入数据excelWriter.write(departmentEmployees.get(i), writeSheet);}}}
}

5.2.2 创建Controller

package com.example.excel.controller;import com.example.excel.model.Employee;
import com.example.excel.service.EasyExcelExportService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.List;@RestController
@RequestMapping("/api/easyexcel")
public class EasyExcelExportController {@Autowiredprivate EasyExcelExportService exportService;@GetMapping("/export")public void exportEmployees(HttpServletResponse response) throws IOException {// 设置响应内容response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");response.setCharacterEncoding("utf-8");// 设置文件名String fileName = URLEncoder.encode("员工数据", StandardCharsets.UTF_8).replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");// 获取测试数据List<Employee> employees = getTestEmployees();// 导出ExcelexportService.exportEmployees(employees, response.getOutputStream());}@GetMapping("/export-multiple-sheets")public void exportMultipleSheets(HttpServletResponse response) throws IOException {// 设置响应内容response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");response.setCharacterEncoding("utf-8");// 设置文件名String fileName = URLEncoder.encode("部门员工数据", StandardCharsets.UTF_8).replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");// 获取测试数据 - 三个部门的员工List<List<Employee>> departmentEmployees = new ArrayList<>();departmentEmployees.add(getEmployeesByDepartment("研发部"));departmentEmployees.add(getEmployeesByDepartment("市场部"));departmentEmployees.add(getEmployeesByDepartment("行政部"));// Sheet名称List<String> sheetNames = Arrays.asList("研发部员工", "市场部员工", "行政部员工");// 导出ExcelexportService.exportMultipleSheets(departmentEmployees, sheetNames, response.getOutputStream());}/*** 生成测试员工数据*/private List<Employee> getTestEmployees() {List<Employee> employees = new ArrayList<>();// 添加测试数据for (int i = 1; i <= 10; i++) {Employee employee = new Employee();employee.setId((long) i);employee.setName("员工" + i);employee.setAge(20 + i);employee.setEmail("employee" + i + "@example.com");employee.setDepartment(i % 3 == 0 ? "研发部" : (i % 3 == 1 ? "市场部" : "行政部"));employee.setHireDate(new Date());employee.setSalary(5000.0 + i * 1000);employees.add(employee);}return employees;}/*** 根据部门获取员工*/private List<Employee> getEmployeesByDepartment(String department) {List<Employee> allEmployees = getTestEmployees();List<Employee> departmentEmployees = new ArrayList<>();for (Employee employee : allEmployees) {if (department.equals(employee.getDepartment())) {departmentEmployees.add(employee);}}return departmentEmployees;}// ... 5.2.3 使用自定义样式和复杂表头/*** 导出自定义样式的Excel*/public void exportWithCustomStyle(List<Employee> employees, OutputStream outputStream) {// 设置自定义拦截器来处理样式EasyExcel.write(outputStream, Employee.class)// 自动调整列宽.registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())// 设置表头样式.registerWriteHandler(new AbstractRowHeightStyleStrategy() {@Overrideprotected void setHeadColumnHeight(Row row, int relativeRowIndex) {// 设置表头行高row.setHeight((short) 500);}@Overrideprotected void setContentColumnHeight(Row row, int relativeRowIndex) {// 设置内容行高row.setHeight((short) 400);}})// 设置单元格样式.registerWriteHandler(new CellWriteHandler() {@Overridepublic void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {// 设置表头样式if (isHead) {Workbook workbook = writeSheetHolder.getSheet().getWorkbook();CellStyle style = workbook.createCellStyle();Font font = workbook.createFont();font.setBold(true);font.setFontHeightInPoints((short) 12);font.setColor(IndexedColors.WHITE.getIndex());style.setFont(font);style.setFillForegroundColor(IndexedColors.ROYAL_BLUE.getIndex());style.setFillPattern(FillPatternType.SOLID_FOREGROUND);style.setAlignment(HorizontalAlignment.CENTER);style.setVerticalAlignment(VerticalAlignment.CENTER);cell.setCellStyle(style);}}@Overridepublic void afterCellDataConverted(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {// 在这里可以根据数据内容设置样式}@Overridepublic void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, List<CellData> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {// 内容行的样式if (!isHead) {// 偶数行设置背景色if (relativeRowIndex % 2 == 0) {Workbook workbook = writeSheetHolder.getSheet().getWorkbook();CellStyle style = workbook.createCellStyle();style.setFillForegroundColor(IndexedColors.PALE_BLUE.getIndex());style.setFillPattern(FillPatternType.SOLID_FOREGROUND);style.setAlignment(HorizontalAlignment.CENTER);style.setVerticalAlignment(VerticalAlignment.CENTER);cell.setCellStyle(style);}}}}).sheet("员工数据").doWrite(employees);}/*** 导出复杂表头的Excel*/public void exportWithComplexHead(List<Employee> employees, OutputStream outputStream) {// 构建复杂表头List<List<String>> head = new ArrayList<>();// 第一列 IDList<String> head1 = new ArrayList<>();head1.add("基本信息");head1.add("员工ID");head.add(head1);// 第二列 姓名List<String> head2 = new ArrayList<>();head2.add("基本信息");head2.add("姓名");head.add(head2);// 第三列 年龄List<String> head3 = new ArrayList<>();head3.add("基本信息");head3.add("年龄");head.add(head3);// 第四列 邮箱List<String> head4 = new ArrayList<>();head4.add("联系方式");head4.add("邮箱");head.add(head4);// 第五列 部门List<String> head5 = new ArrayList<>();head5.add("工作信息");head5.add("部门");head.add(head5);// 第六列 入职日期List<String> head6 = new ArrayList<>();head6.add("工作信息");head6.add("入职日期");head.add(head6);// 第七列 薪资List<String> head7 = new ArrayList<>();head7.add("薪资信息");head7.add("月薪(元)");head.add(head7);// 将数据转为List<List<Object>>格式List<List<Object>> dataList = new ArrayList<>();for (Employee employee : employees) {List<Object> data = new ArrayList<>();data.add(employee.getId());data.add(employee.getName());data.add(employee.getAge());data.add(employee.getEmail());data.add(employee.getDepartment());data.add(employee.getHireDate());data.add(employee.getSalary());dataList.add(data);}// 写入ExcelEasyExcel.write(outputStream).head(head).registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()).sheet("员工数据").doWrite(dataList);}
}

6. 处理大型Excel文件的策略

6.1 使用Apache POI SXSSF模式

SXSSF（Streaming Xlsx Writer）是POI提供的流式写入方式，可以大大减少内存使用：

public void exportLargeExcel(String fileName, int rowCount) throws IOException {try (SXSSFWorkbook workbook = new SXSSFWorkbook(100)) { // 100表示内存中保留的行数Sheet sheet = workbook.createSheet("大数据");// 创建表头Row headerRow = sheet.createRow(0);for (int i = 0; i < 10; i++) {headerRow.createCell(i).setCellValue("列 " + (i + 1));}// 创建数据行for (int i = 0; i < rowCount; i++) {Row row = sheet.createRow(i + 1);for (int j = 0; j < 10; j++) {row.createCell(j).setCellValue("数据 " + (i + 1) + "-" + (j + 1));}// 每生成10000行清理一次临时文件if (i % 10000 == 0) {((SXSSFSheet)sheet).flushRows();}}// 写入文件try (FileOutputStream outputStream = new FileOutputStream(fileName)) {workbook.write(outputStream);}// 清理临时文件workbook.dispose();}
}

注意事项：

1. 使用完毕后一定要调用dispose()方法清理临时文件
2. SXSSF仅支持写入操作，不支持读取
3. 不支持某些高级特性（如合并单元格等）

6.2 使用EasyExcel处理大文件

EasyExcel在设计上就考虑了大文件处理，采用SAX方式逐行读取，内存占用小：

// 读取大文件
public void readLargeExcel(String fileName) {// 使用SAX方式读取EasyExcel.read(fileName, Employee.class, new EmployeeReadListener()).sheet().doRead();
}// 写入大文件
public void writeLargeExcel(String fileName, int batchSize) {// 分批获取数据try (ExcelWriter excelWriter = EasyExcel.write(fileName, Employee.class).registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()).build()) {// 获取WriteSheet对象WriteSheet writeSheet = EasyExcel.writerSheet("员工数据").build();// 模拟分批获取数据int totalCount = 100000; // 总数据量for (int i = 0; i < totalCount; i += batchSize) {// 获取当前批次数据List<Employee> data = getBatchData(i, Math.min(i + batchSize, totalCount));// 写入ExcelexcelWriter.write(data, writeSheet);}}
}// 模拟分批获取数据
private List<Employee> getBatchData(int start, int end) {List<Employee> list = new ArrayList<>();for (int i = start; i < end; i++) {Employee employee = new Employee();employee.setId((long) i);employee.setName("员工" + i);employee.setAge(20 + (i % 20));employee.setEmail("employee" + i + "@example.com");employee.setDepartment(i % 3 == 0 ? "研发部" : (i % 3 == 1 ? "市场部" : "行政部"));employee.setHireDate(new Date());employee.setSalary(5000.0 + (i % 10) * 1000);list.add(employee);}return list;
}

6.3 使用CSV代替Excel

对于极大的数据集，考虑使用CSV格式替代Excel：

public void exportToCsv(List<Employee> employees, String fileName) throws IOException {try (FileWriter writer = new FileWriter(fileName);CSVPrinter csvPrinter = new CSVPrinter(writer, CSVFormat.DEFAULT.withHeader("ID", "姓名", "年龄", "邮箱", "部门", "入职日期", "薪资"))) {for (Employee employee : employees) {csvPrinter.printRecord(employee.getId(),employee.getName(),employee.getAge(),employee.getEmail(),employee.getDepartment(),employee.getHireDate(),employee.getSalary());}csvPrinter.flush();}
}

注意：使用CSV需要添加依赖：

<dependency><groupId>org.apache.commons</groupId><artifactId>commons-csv</artifactId><version>1.9.0</version>
</dependency>

6.4 分页导出大型数据集

对于Web应用中需要导出的大型数据集，可以考虑分页导出：

@GetMapping("/export/paged")
public ResponseEntity<String> exportPaged() {// 生成唯一任务IDString taskId = UUID.randomUUID().toString();// 启动异步任务CompletableFuture.runAsync(() -> {try {// 导出文件路径String filePath = "/temp/" + taskId + ".xlsx";// 分页查询数据并写入Excelint pageSize = 1000;int totalPages = getTotalPages(pageSize);try (ExcelWriter excelWriter = EasyExcel.write(filePath, Employee.class).registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()).build()) {WriteSheet writeSheet = EasyExcel.writerSheet("员工数据").build();// 分页导出for (int pageNum = 0; pageNum < totalPages; pageNum++) {// 从数据库分页查询数据List<Employee> pageData = getPageData(pageNum, pageSize);// 写入ExcelexcelWriter.write(pageData, writeSheet);// 更新进度updateExportProgress(taskId, (pageNum + 1) * 100 / totalPages);}}// 更新导出状态为完成updateExportStatus(taskId, "COMPLETED", filePath);} catch (Exception e) {// 更新导出状态为失败updateExportStatus(taskId, "FAILED", null);}});// 返回任务IDreturn ResponseEntity.ok(taskId);
}@GetMapping("/export/status/{taskId}")
public ResponseEntity<Map<String, Object>> getExportStatus(@PathVariable String taskId) {// 获取任务状态Map<String, Object> status = getTaskStatus(taskId);return ResponseEntity.ok(status);
}@GetMapping("/export/download/{taskId}")
public ResponseEntity<Resource> downloadExportedFile(@PathVariable String taskId) {// 获取导出文件路径String filePath = getExportedFilePath(taskId);if (filePath == null) {return ResponseEntity.notFound().build();}// 创建文件资源Resource resource = new FileSystemResource(filePath);return ResponseEntity.ok().header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=employee_data.xlsx").contentType(MediaType.parseMediaType("application/vnd.ms-excel")).body(resource);
}

7. 实际应用场景和最佳实践

7.1 动态列导出

在某些业务场景中，需要根据用户选择动态确定导出的列：

public ByteArrayInputStream exportDynamicColumns(List<Employee> employees, List<String> selectedColumns) throws IOException {// 定义所有可能的列Map<String, String> allColumns = new HashMap<>();allColumns.put("id", "员工ID");allColumns.put("name", "姓名");allColumns.put("age", "年龄");allColumns.put("email", "邮箱");allColumns.put("department", "部门");allColumns.put("hireDate", "入职日期");allColumns.put("salary", "薪资");try (Workbook workbook = new XSSFWorkbook()) {Sheet sheet = workbook.createSheet("员工数据");// 创建表头行Row headerRow = sheet.createRow(0);// 设置表头样式CellStyle headerStyle = workbook.createCellStyle();Font headerFont = workbook.createFont();headerFont.setBold(true);headerStyle.setFont(headerFont);// 填充表头int colIdx = 0;for (String column : selectedColumns) {if (allColumns.containsKey(column)) {Cell cell = headerRow.createCell(colIdx++);cell.setCellValue(allColumns.get(column));cell.setCellStyle(headerStyle);}}// 填充数据int rowIdx = 1;for (Employee employee : employees) {Row row = sheet.createRow(rowIdx++);colIdx = 0;for (String column : selectedColumns) {Cell cell = row.createCell(colIdx++);// 根据列名设置单元格值switch (column) {case "id":cell.setCellValue(employee.getId());break;case "name":cell.setCellValue(employee.getName());break;case "age":cell.setCellValue(employee.getAge());break;case "email":cell.setCellValue(employee.getEmail());break;case "department":cell.setCellValue(employee.getDepartment());break;case "hireDate":if (employee.getHireDate() != null) {cell.setCellValue(employee.getHireDate());// 设置日期格式CellStyle dateStyle = workbook.createCellStyle();CreationHelper createHelper = workbook.getCreationHelper();dateStyle.setDataFormat(createHelper.createDataFormat().getFormat("yyyy-mm-dd"));cell.setCellStyle(dateStyle);}break;case "salary":cell.setCellValue(employee.getSalary());break;}}}// 自动调整列宽for (int i = 0; i < selectedColumns.size(); i++) {sheet.autoSizeColumn(i);}// 输出ByteArrayOutputStream outputStream = new ByteArrayOutputStream();workbook.write(outputStream);return new ByteArrayInputStream(outputStream.toByteArray());}
}

7.2 Excel模板填充

使用Freemarker或其他模板引擎生成Excel：

public ByteArrayInputStream fillTemplate(Map<String, Object> data) throws Exception {// 加载模板Configuration cfg = new Configuration(Configuration.VERSION_2_3_30);cfg.setClassLoaderForTemplateLoading(getClass().getClassLoader(), "templates");cfg.setDefaultEncoding("UTF-8");// 获取模板Template template = cfg.getTemplate("excel_template.ftl");// 输出目录File tempDir = new File(System.getProperty("java.io.tmpdir"));File tempFile = new File(tempDir, "temp_" + System.currentTimeMillis() + ".xlsx");// 填充模板try (Writer out = new FileWriter(tempFile)) {template.process(data, out);}// 读取填充后的文件try (FileInputStream fis = new FileInputStream(tempFile)) {ByteArrayOutputStream baos = new ByteArrayOutputStream();byte[] buffer = new byte[1024];int len;while ((len = fis.read(buffer)) > -1) {baos.write(buffer, 0, len);}baos.flush();// 删除临时文件tempFile.delete();return new ByteArrayInputStream(baos.toByteArray());}
}

7.3 Excel文件校验

在导入Excel文件前进行数据校验：

public class ExcelValidationListener extends AnalysisEventListener<Employee> {private List<Employee> validEmployees = new ArrayList<>();private List<Map<String, Object>> errorRecords = new ArrayList<>();private int rowIndex = 1; // 从1开始，0是表头@Overridepublic void invoke(Employee employee, AnalysisContext context) {rowIndex++;// 验证数据List<String> errors = validateEmployee(employee);if (errors.isEmpty()) {// 数据有效validEmployees.add(employee);} else {// 记录错误Map<String, Object> errorRecord = new HashMap<>();errorRecord.put("rowIndex", rowIndex);errorRecord.put("data", employee);errorRecord.put("errors", errors);errorRecords.add(errorRecord);}}@Overridepublic void doAfterAllAnalysed(AnalysisContext context) {// 处理完成}// 验证员工数据private List<String> validateEmployee(Employee employee) {List<String> errors = new ArrayList<>();// 验证姓名if (employee.getName() == null || employee.getName().trim().isEmpty()) {errors.add("姓名不能为空");}// 验证年龄if (employee.getAge() == null) {errors.add("年龄不能为空");} else if (employee.getAge() < 18 || employee.getAge() > 65) {errors.add("年龄必须在18-65岁之间");}// 验证邮箱if (employee.getEmail() != null && !employee.getEmail().isEmpty()) {String emailRegex = "^[a-zA-Z0-9_+&*-]+(?:\\.[a-zA-Z0-9_+&*-]+)*@" +"(?:[a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,7}$";if (!employee.getEmail().matches(emailRegex)) {errors.add("邮箱格式不正确");}}// 验证部门if (employee.getDepartment() == null || employee.getDepartment().trim().isEmpty()) {errors.add("部门不能为空");}// 验证薪资if (employee.getSalary() != null && employee.getSalary() < 0) {errors.add("薪资不能为负数");}return errors;}public List<Employee> getValidEmployees() {return validEmployees;}public List<Map<String, Object>> getErrorRecords() {return errorRecords;}public boolean hasErrors() {return !errorRecords.isEmpty();}
}

7.4 统一异常处理

为Excel处理添加统一的异常处理：

@ControllerAdvice
public class ExcelExceptionHandler {private static final Logger logger = LoggerFactory.getLogger(ExcelExceptionHandler.class);@ExceptionHandler(IOException.class)public ResponseEntity<Map<String, String>> handleIOException(IOException e) {logger.error("文件读写异常", e);Map<String, String> response = new HashMap<>();response.put("error", "文件读写异常");response.put("message", e.getMessage());return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(response);}@ExceptionHandler(IllegalArgumentException.class)public ResponseEntity<Map<String, String>> handleIllegalArgumentException(IllegalArgumentException e) {logger.error("参数异常", e);Map<String, String> response = new HashMap<>();response.put("error", "参数异常");response.put("message", e.getMessage());return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(response);}@ExceptionHandler(Exception.class)public ResponseEntity<Map<String, String>> handleGenericException(Exception e) {logger.error("Excel处理异常", e);Map<String, String> response = new HashMap<>();response.put("error", "Excel处理异常");response.put("message", e.getMessage());return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(response);}
}

8. 性能优化和注意事项

8.1 性能优化建议

1. 使用适当的Excel库：

   • 小文件可使用Apache POI
   • 大文件请使用EasyExcel或POI的SXSSF模式
   • 极大文件考虑使用CSV格式

2. 避免一次性加载整个文件：

   • 读取时使用流式解析
   • 写入时使用分批写入

3. 合理设置缓冲区大小：

   • 在SXSSFWorkbook中设置合理的内存行数
   • 在批处理中选择合适的批次大小

4. 减少样式对象：

   • 样式对象重用，而不是为每个单元格创建新样式
   • 限制使用的颜色、字体和边框样式数量

5. 使用异步处理：

   • 将大文件处理放在后台线程中执行
   • 提供进度反馈机制

8.2 注意事项

1. 内存管理：

   • 注意监控JVM内存使用情况
   • 对于大文件处理，考虑增加JVM堆内存（-Xmx参数）
   • 使用完毕后及时关闭资源和清理临时文件

2. 安全考虑：

   • 限制上传文件大小
   • 验证文件类型和内容
   • 防止恶意Excel文件（包含宏或公式）

3. 编码问题：

   • 处理国际字符时，确保使用正确的字符编码
   • 文件名包含中文时，确保正确编码

4. 并发控制：

   • 大文件处理时注意服务器负载
   • 限制并发处理任务数量

5. 临时文件清理：

   • 使用SXSSF时，必须调用dispose()方法清理临时文件
   • 定期清理服务器上的临时文件

9. 总结

Spring Boot提供了强大而灵活的Excel处理能力，通过结合Apache POI和EasyExcel等工具，可以轻松实现Excel文件的读取、创建和导出功能。在实际应用中，应根据具体需求和数据量选择合适的处理策略，既要保证功能完整，又要注重性能和资源使用。

无论是简单的数据导出，还是复杂的报表生成，或是大数据量的文件处理，都可以通过本文介绍的方法灵活实现。重点是要根据实际业务场景，选择合适的技术方案，并注意性能优化和异常处理。