目录
一、EasyExcel介绍
1、简介
**EasyExcel是阿里巴巴开源poi插件之一，是一个基于Java的、快速、简洁、解决大文件内存溢出的Excel处理工具。**尽管Java解析、生成Excel不止EasyExcel，还有一些其他的框架，例如：Apache poi、jxl，但这些都存在一个严重的问题就是非常的耗内存。而EasyExcel是在尽可能节约内存的情况下支持读写百M的Excel，能在不用考虑性能、内存的等因素的情况下，快速完成Excel的读、写等功能。因此，本文将通过一个书籍列表的导入，作为案例，来揭开EasyExcel的使用过程。
2、常用注解
- @ExcelProperty：指定当前字段对应excel中的那一列。可以根据名字或者Index去匹配。当然也可以不写，默认第一个字段就是index=0，以此类推。千万注意，要么全部不写，要么全部用index，要么全部用名字去匹配。千万别三个混着用，除非你非常了解源代码中三个混着用怎么去排序的。
- @ExcelIgnore：默认所有字段都会和excel去匹配，加了这个注解会忽略该字段
- @DateTimeFormat：日期转换，用String去接收excel日期格式的数据会调用这个注解。里面的value参照java.text.SimpleDateFormat
- @NumberFormat：数字转换，用String去接收excel数字格式的数据会调用这个注解。里面的value参照java.text.DecimalFormat
- @ExcelIgnoreUnannotated：默认不加ExcelProperty 的注解的都会参与读写，加了不会参与
二、SpringBoot整合EasyExcel
1、基本环境
(1)引入依赖
XML
<!-- 查看excel的maven仓库 https://mvnrepository.com/artifact/com.alibaba/easyexcel -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>easyexcel</artifactId>
<version>3.1.2</version>
</dependency>(2)创建实体类
java
import com.alibaba.excel.annotation.ExcelProperty;
import com.alibaba.excel.annotation.format.DateTimeFormat;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import java.math.BigDecimal;
@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
public class Book {
@ExcelProperty(value = "发布日期")
@DateTimeFormat("yyyy-MM-dd")
private String publishDate;
@ExcelProperty("书名")
private String bookName;
@ExcelProperty("作者")
private String author;
@ExcelProperty("价格")
private BigDecimal price;
@ExcelProperty("售卖数量")
private Integer saleNum;
@ExcelProperty(value = "是否热卖")
private String status;
}2、EasyExcel内容读取
(1)创建监听器
java
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.example.yht.entity.Book;
import java.util.*;
public class ExcelListener extends AnalysisEventListener<Book> {
@Override
public void invokeHeadMap(Map<Integer, String> headMap, AnalysisContext context) {
System.out.println("解析表头信息");
System.out.println(headMap);
}
@Override
public void onException(Exception exception, AnalysisContext context) {
System.out.println("Error Message : " + exception);
}
@Override
public void invoke(Book book, AnalysisContext analysisContext) {
System.out.println(book);
}
@Override
public void doAfterAllAnalysed(AnalysisContext analysisContext) {
System.out.println("解析完毕");
}
@Override
public boolean hasNext(AnalysisContext context) {
return super.hasNext(context);
}
}(2)测试
主方法：
java
public static void main(String[] args) {
String filename="D:\\其他\\书籍列表.xlsx";
System.out.println("Excel内容如下：");
ExcelListener excelListener = new ExcelListener();
EasyExcel.read(filename, Book.class, excelListener).sheet(0).doRead();
}测试结果：
3、EasyExcel内容校验
(1)场景描述
上面介绍的内容只是一个简单的Excel读取案例。接下来，我们可以在解析加一些校验规则，例如：书籍的发布日期格式必须为YYYY-MM-DD格式；价格的整数位不能超过10位，小数位不能超过三位。接下来就来改造ExcelListener，以实现我们的需求。
(2)EasyExcel监听器
java
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.alibaba.excel.exception.ExcelAnalysisException;
import com.alibaba.excel.exception.ExcelAnalysisStopException;
import com.alibaba.excel.exception.ExcelDataConvertException;
import com.example.yht.entity.Book;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;
import java.util.regex.Pattern;
public class ExcelListener extends AnalysisEventListener<Book> {
private List<Book> list = new ArrayList<>();
private List<String> errList= new ArrayList<>();
public List<Book> getList() {
return list;
}
public void setList(List<Book> list) {
this.list = list;
}
public List<String> getErrList() {
return errList;
}
public void setErrList(List<String> errList) {
this.errList = errList;
}
public int getRow() {
return row;
}
public void setRow(int row) {
this.row = row;
}
public int getCol() {
return col;
}
public void setCol(int col) {
this.col = col;
}
public Map<Integer, String> getErrorMessageMap() {
return errorMessageMap;
}
private int row = 1;
private int col = 1;
private final Map<Integer, String> errorMessageMap = new HashMap<>();
@Override
public void invokeHeadMap(Map<Integer, String> headMap, AnalysisContext context) {
System.out.println("解析表头信息");
System.out.println(headMap);
row++;
}
@Override
public void onException(Exception exception, AnalysisContext context) {
String errMsg = "第" + row + "行, 第" + col + "列解析失败";
errList.add(errMsg);
row++ ;
if(exception instanceof ExcelAnalysisException) {
throw new ExcelAnalysisStopException("解析失败！");
}else{
throw new ExcelAnalysisStopException("解析失败！");
}
}
@Override
public void invoke(Book book, AnalysisContext analysisContext) {
if(book == null){
return;
}
if(!preDealEntity(book)){
throw new ExcelAnalysisException("数据解析错误");
}
list.add(book);
row++;
}
public boolean preDealEntity(Book book){
if(null == book){
return false;
}
Field[] fields = book.getClass().getDeclaredFields();
col = 1;
for(int i=0; i < fields.length; i++){
Field field = fields[i];
field.setAccessible(true);
try {
Object val = field.get(book);
if(val != null){
if(field.getName().equals("publishDate") && !isValidDate((String)val, "yyyy-MM-dd")){
return false;
}
if(val instanceof BigDecimal && !isNumeric(val+"")){
return false;
}
}
col++;
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
return true;
}
public static boolean isNumeric(String str) {
if (null == str || "".equals(str)) {
return false;
}
String regx = "[+-]*\\d+\\.?\\d*[Ee]*[+-]*\\d+";
Pattern pattern = Pattern.compile(regx);
boolean isNumber = pattern.matcher(str).matches();
if (!isNumber) {
return isNumber;
}
regx = "^[-\\+]?[.\\d]*$";
pattern = Pattern.compile(regx);
isNumber = pattern.matcher(str).matches();
if (!isNumber) {
return isNumber;
}
String[] arrs = str.split("\\.");
return arrs[0].length() <= 10 && arrs[1].length() <= 3;
}
public static boolean isValidDate(String dateStr, String format) {
SimpleDateFormat sdf = new SimpleDateFormat(format);
sdf.setLenient(false); // 设置解析日期时严格匹配，不容忍格式错误
try {
sdf.parse(dateStr);
return true;
} catch (ParseException e) {
return false;
}
}
@Override
public void doAfterAllAnalysed(AnalysisContext analysisContext) {
System.out.println("解析完毕");
}
@Override
public boolean hasNext(AnalysisContext context) {
return super.hasNext(context);
}
}(3)测试
主方法：
java
public static void main(String[] args) {
//SpringApplication.run(FtpDemoApplication.class);
String filename="D:\\其他\\书籍列表.xlsx";
System.out.println("Excel内容如下：");
ExcelListener excelListener = new ExcelListener();
EasyExcel.read(filename, Book.class, excelListener).sheet(0).doRead();
if(excelListener.getErrList().isEmpty()){
System.out.println("所有数据解析成功！");
System.out.println(excelListener.getList());
}else{
System.out.println("数据解析失败：");
System.out.println(excelListener.getErrList());
}
}第一种情况：解析正常的情况
java
Excel内容如下：
21:05:22.869 [main] DEBUG com.alibaba.excel.metadata.property.ExcelHeadProperty - The initialization sheet/table 'ExcelHeadProperty' is complete , head kind is CLASS
21:05:22.891 [main] DEBUG com.alibaba.excel.context.AnalysisContextImpl - Initialization 'AnalysisContextImpl' complete
21:05:23.018 [main] DEBUG com.alibaba.excel.cache.selector.SimpleReadCacheSelector - Use map cache.size:590
21:05:23.227 [main] DEBUG com.alibaba.excel.metadata.property.ExcelHeadProperty - The initialization sheet/table 'ExcelHeadProperty' is complete , head kind is CLASS
21:05:23.227 [main] DEBUG com.alibaba.excel.context.AnalysisContextImpl - Began to read：com.alibaba.excel.read.metadata.holder.xlsx.XlsxReadSheetHolder@6a021575
解析表头信息
{0=发布日期, 1=书名, 2=作者, 3=价格, 4=售卖数量, 5=是否热卖}
解析完毕
所有数据解析成功！
[Book(publishDate=2013-5-4, bookName=三国演义, author=罗贯中, price=24.15, saleNum=34, status=是), Book(publishDate=2016-2-14, bookName=水浒传, author=施耐庵, price=49.34, saleNum=23, status=否), Book(publishDate=2013-12-14, bookName=三国演义, author=罗贯中, price=24.15, saleNum=1, status=是)]
Process finished with exit code 0在表格中添加一些错误数据，如下：
可以看到：上面的代码案例中，如果某一行解析失败，则剩余行不做解析，直接返回解析错误的信息。
**还有另外一种错误情况：如果某一行解析失败，剩余行依旧需要解析，直到解析完毕返回所有的错误信息。**那么可以将监听器代码改成下面这样：
java
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.alibaba.excel.exception.ExcelAnalysisException;
import com.alibaba.excel.exception.ExcelAnalysisStopException;
import com.alibaba.excel.exception.ExcelDataConvertException;
import com.example.yht.entity.Book;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;
import java.util.regex.Pattern;
public class ExcelListener extends AnalysisEventListener<Book> {
private List<Book> list = new ArrayList<>();
private List<String> errList= new ArrayList<>();
public List<Book> getList() {
return list;
}
public void setList(List<Book> list) {
this.list = list;
}
public List<String> getErrList() {
return errList;
}
public void setErrList(List<String> errList) {
this.errList = errList;
}
public int getRow() {
return row;
}
public void setRow(int row) {
this.row = row;
}
public int getCol() {
return col;
}
public void setCol(int col) {
this.col = col;
}
public Map<Integer, String> getErrorMessageMap() {
return errorMessageMap;
}
private int row = 1;
private int col = 1;
private final Map<Integer, String> errorMessageMap = new HashMap<>();
@Override
public void invokeHeadMap(Map<Integer, String> headMap, AnalysisContext context) {
System.out.println("解析表头信息");
System.out.println(headMap);
row++;
}
@Override
public void onException(Exception exception, AnalysisContext context) {
String errMsg = "第" + row + "行, 第" + col + "列解析失败";
row++ ;
}
@Override
public void invoke(Book book, AnalysisContext analysisContext) {
if(book == null){
return;
}
preDealEntity(book);
list.add(book);
row++;
}
public void preDealEntity(Book book){
if(null == book){
return;
}
Field[] fields = book.getClass().getDeclaredFields();
col = 1;
for(int i=0; i < fields.length; i++){
Field field = fields[i];
field.setAccessible(true);
try {
Object val = field.get(book);
if(val != null){
if(field.getName().equals("publishDate") && !isValidDate((String)val, "yyyy-MM-dd")){
String errMsg = "第" + row + "行, 第" + col + "列解析失败";
errList.add(errMsg);
}
if(val instanceof BigDecimal && !isNumeric(val+"")){
String errMsg = "第" + row + "行, 第" + col + "列解析失败";
errList.add(errMsg);
}
}
col++;
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
public static boolean isNumeric(String str) {
if (null == str || "".equals(str)) {
return false;
}
String regx = "[+-]*\\d+\\.?\\d*[Ee]*[+-]*\\d+";
Pattern pattern = Pattern.compile(regx);
boolean isNumber = pattern.matcher(str).matches();
if (!isNumber) {
return isNumber;
}
regx = "^[-\\+]?[.\\d]*$";
pattern = Pattern.compile(regx);
isNumber = pattern.matcher(str).matches();
if (!isNumber) {
return isNumber;
}
String[] arrs = str.split("\\.");
return arrs[0].length() <= 10 && arrs[1].length() <= 3;
}
public static boolean isValidDate(String dateStr, String format) {
SimpleDateFormat sdf = new SimpleDateFormat(format);
sdf.setLenient(false); // 设置解析日期时严格匹配，不容忍格式错误
try {
sdf.parse(dateStr);
return true;
} catch (ParseException e) {
return false;
}
}
@Override
public void doAfterAllAnalysed(AnalysisContext analysisContext) {
System.out.println("解析完毕");
}
@Override
public boolean hasNext(AnalysisContext context) {
return super.hasNext(context);
}
}
4、EasyExcel内容批量插入数据库
(1)创建数据库
sql
create table t_book(
publish_date date,
book_name varchar(50),
author varchar(20),
price decimal(10,3),
sale_num int,
status tinyint(1)
);(2)编写Mapper
java
@Mapper
public interface BookMapper {
Integer saveBook(@Param("bookList") List<Book> bookList);
}
XML
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace：指定了唯一的命名空间-->
<mapper namespace="com.example.yht.mapper.BookMapper">
<insert id="saveBook">
insert into t_book(publish_date, book_name, author, price, sale_num, status)
VALUES
<foreach collection="bookList" index="" item="book" separator=",">
(#{book.publishDate},
#{book.bookName},
#{book.author},
#{book.price},
#{book.saleNum},
#{book.status})
</foreach>
</insert>
</mapper>(3)编写Service
java
public interface IBookService {
Integer saveBook(List<Book> bookList);
}
java
@Service
public class BookServiceImpl implements IBookService {
@Autowired
private BookMapper bookMapper;
@Override
public Integer saveBook(List<Book> bookList) {
return bookMapper.saveBook(bookList);
}
}(4)Controller层
java
import com.alibaba.excel.EasyExcel;
import com.example.yht.entity.Book;
import com.example.yht.entity.Student;
import com.example.yht.listener.ExcelListener;
import com.example.yht.service.IBookService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import java.text.SimpleDateFormat;
@RestController
public class TestController {
@Autowired
private IBookService bookService;
@GetMapping("/excelToDB")
public void excelToDB(){
String filename="D:\\其他\\书籍列表.xlsx";
System.out.println("Excel内容如下：");
ExcelListener excelListener = new ExcelListener(bookService);
EasyExcel.read(filename, Book.class, excelListener).sheet(0).doRead();
if(excelListener.getErrList().isEmpty()){
System.out.println("所有数据解析成功！");
}else{
System.out.println("数据解析失败：");
System.out.println(excelListener.getErrList());
}
}
}(5)自定义转换器
从Excel中可以看到一个细节，是否热卖这一列在excel里面的值有两种：是/否。但是在数据库里面，status的类型却是tinyint。因此我们就需要将excel里面的是/否转换为1/0，从而存储在数据库中。这里我们介绍一个Excel的转换器，可以实现这项操作。
这里首先将Book的实体类中的status改为Integer类型：
java
@ExcelProperty(value = "是否热卖", converter = StatusConverter.class)
private Integer status;
java
import com.alibaba.excel.converters.Converter;
import com.alibaba.excel.converters.ReadConverterContext;
import com.alibaba.excel.converters.WriteConverterContext;
import com.alibaba.excel.enums.CellDataTypeEnum;
import com.alibaba.excel.metadata.GlobalConfiguration;
import com.alibaba.excel.metadata.data.ReadCellData;
import com.alibaba.excel.metadata.data.WriteCellData;
import com.alibaba.excel.metadata.property.ExcelContentProperty;
public class StatusConverter implements Converter<Integer> {
@Override
public Class<?> supportJavaTypeKey() {
return Converter.super.supportJavaTypeKey();
}
@Override
public CellDataTypeEnum supportExcelTypeKey() {
return Converter.super.supportExcelTypeKey();
}
@Override
public Integer convertToJavaData(ReadCellData<?> cellData, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) throws Exception {
return Converter.super.convertToJavaData(cellData, contentProperty, globalConfiguration);
}
@Override
public Integer convertToJavaData(ReadConverterContext<?> context) throws Exception {
return context.getReadCellData().getStringValue().equals("是") ? 1 : 0;
}
@Override
public WriteCellData<?> convertToExcelData(Integer value, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) throws Exception {
return new WriteCellData<Integer>(value.equals(1) ? "是" : "否");
}
}(6)EasyExcel监听器
java
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.alibaba.excel.exception.ExcelAnalysisException;
import com.alibaba.excel.exception.ExcelAnalysisStopException;
import com.alibaba.excel.exception.ExcelDataConvertException;
import com.alibaba.excel.util.ListUtils;
import com.example.yht.entity.Book;
import com.example.yht.service.IBookService;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;
import java.util.regex.Pattern;
public class ExcelListener extends AnalysisEventListener<Book> {
//假设每5条插入一次数据库
private static int BATCH_COUNT = 5;
private List<Book> bookList = new ArrayList<>();
private List<String> errList= new ArrayList<>();
private IBookService bookService;
public ExcelListener(IBookService bookService) {
this.bookService = bookService;
}
public List<Book> getBookList() {
return bookList;
}
public void setBookList(List<Book> bookList) {
this.bookList = bookList;
}
public List<String> getErrList() {
return errList;
}
public void setErrList(List<String> errList) {
this.errList = errList;
}
public int getRow() {
return row;
}
public void setRow(int row) {
this.row = row;
}
public int getCol() {
return col;
}
public void setCol(int col) {
this.col = col;
}
public Map<Integer, String> getErrorMessageMap() {
return errorMessageMap;
}
private int row = 1;
private int col = 1;
private final Map<Integer, String> errorMessageMap = new HashMap<>();
@Override
public void invokeHeadMap(Map<Integer, String> headMap, AnalysisContext context) {
System.out.println("解析表头信息");
System.out.println(headMap);
row++;
}
@Override
public void onException(Exception exception, AnalysisContext context) {
String errMsg = "第" + row + "行, 第" + col + "列解析失败";
errList.add(errMsg);
System.out.println(exception);
row++ ;
if(exception instanceof ExcelAnalysisException) {
throw new ExcelAnalysisStopException("解析失败！");
}else{
throw new ExcelAnalysisStopException("解析失败！");
}
}
@Override
public void invoke(Book book, AnalysisContext analysisContext) {
if(book == null){
return;
}
if(!preDealEntity(book)){
throw new ExcelAnalysisException("数据解析错误");
}
bookList.add(book);
if(bookList.size() >= BATCH_COUNT){
saveData(bookList);
}
row++;
}
/**
* 保存数据
* @param list
*/
private void saveData(List<Book> list) {
bookService.saveBook(list);
bookList = ListUtils.newArrayListWithExpectedSize(BATCH_COUNT);
}
public boolean preDealEntity(Book book){
if(null == book){
return false;
}
Field[] fields = book.getClass().getDeclaredFields();
col = 1;
for(int i=0; i < fields.length; i++){
Field field = fields[i];
field.setAccessible(true);
try {
Object val = field.get(book);
if(val != null){
if(field.getName().equals("publishDate") && !isValidDate((String)val, "yyyy-MM-dd")){
return false;
}
if(val instanceof BigDecimal && !isNumeric(val+"")){
return false;
}
}
col++;
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
return true;
}
public static boolean isNumeric(String str) {
if (null == str || "".equals(str)) {
return false;
}
String regx = "[+-]*\\d+\\.?\\d*[Ee]*[+-]*\\d+";
Pattern pattern = Pattern.compile(regx);
boolean isNumber = pattern.matcher(str).matches();
if (!isNumber) {
return isNumber;
}
regx = "^[-\\+]?[.\\d]*$";
pattern = Pattern.compile(regx);
isNumber = pattern.matcher(str).matches();
if (!isNumber) {
return isNumber;
}
String[] arrs = str.split("\\.");
return arrs[0].length() <= 10 && arrs[1].length() <= 3;
}
public static boolean isValidDate(String dateStr, String format) {
SimpleDateFormat sdf = new SimpleDateFormat(format);
sdf.setLenient(false); // 设置解析日期时严格匹配，不容忍格式错误
try {
sdf.parse(dateStr);
return true;
} catch (ParseException e) {
return false;
}
}
@Override
public void doAfterAllAnalysed(AnalysisContext analysisContext) {
System.out.println("解析完毕");
//解析完之后，将list中的数据保存在数据库中
saveData(bookList);
}
@Override
public boolean hasNext(AnalysisContext context) {
return super.hasNext(context);
}
}(7)测试
页面请求：http://localhost:8800/excelToDB
终端输出：
数据库内容：
5、EasyExcel写入文件（基础版）
(1)写入操作
这里先看一个基本的案例，首先指定文件位置，并添加一些模拟数据，再通过write方法写入该文件中。
java
@GetMapping("/writeBasic")
public void writeBasic(){
String fileName = "D:\\Data\\easyexcel.xlsx";
List<Book> list = new ArrayList<>();
list.add(new Book("2022-12-1", "人物传记1", "迪丽热巴1", new BigDecimal("34.5"), 20, 1));
list.add(new Book("2022-12-2", "人物传记2", "迪丽热巴2", new BigDecimal("44.5"), 30, 0));
list.add(new Book("2022-12-3", "人物传记3", "迪丽热巴3", new BigDecimal("54.5"), 40, 1));
EasyExcel.write(fileName, Book.class).sheet("模板").doWrite(list);
}(2)测试结果
浏览器请求：http://localhost:8800/writeBasic
6、EasyExcel写入文件（Web模式基础版）
(1)Web模式写入操作
Web模式的写入操作，可以在页面发起请求的时候，将数据内容写入到excel中，并下载到本地。代码如下：
java
@GetMapping("/doWrite")
public void download(HttpServletResponse response) throws IOException {
// 这里直接用浏览器或者用postman
response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
response.setCharacterEncoding("utf-8");
String fileName = URLEncoder.encode("书籍列表.xlsx", "UTF-8").replaceAll("\\+", "%20");
response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName);
//模拟要写入excel的数据
List<Book> list = new ArrayList<>();
list.add(new Book("2023-1-1", "花朵1", "张清1", new BigDecimal("34.5"), 20, 1));
list.add(new Book("2023-1-2", "花朵2", "张清2", new BigDecimal("44.5"), 30, 0));
list.add(new Book("2023-1-3", "花朵3", "张清3", new BigDecimal("54.5"), 40, 1));
EasyExcel.write(response.getOutputStream(), Book.class).sheet("新增").doWrite(list);
}(2)测试结果
浏览器发起请求：http://localhost:8800/doWrite
文件下载：
表格内容：
7、EasyExcel写入文件（Web模式进阶版）
(1)Web模式写入操作进阶版
这里的进阶版是在基础班的上面，加入了文件流的关闭操作等。
java
@GetMapping("/doWrite2")
public void downloadAdvanced(HttpServletResponse response){
//模拟写入的数据
List<Book> list = new ArrayList<>();
list.add(new Book("2023-2-1", "碧螺春1", "肖战1", new BigDecimal("34.5"), 20, 1));
list.add(new Book("2023-2-2", "碧螺春2", "肖战2", new BigDecimal("44.5"), 30, 0));
list.add(new Book("2023-2-3", "碧螺春3", "肖战3", new BigDecimal("54.5"), 40, 1));
try {
response.setContentType("application/vnd.ms-excel");
response.setCharacterEncoding("utf-8");
//防止中文乱码
String fileName = URLEncoder.encode("书籍列表-new.xlsx", "UTF-8").replaceAll("\\+", "%20");
response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName);
ServletOutputStream outputStream = response.getOutputStream();
//工作簿对象
ExcelWriterBuilder writerWork = EasyExcel.write(outputStream, Book.class);
//工作表对象
ExcelWriterSheetBuilder sheet = writerWork.sheet(0);
sheet.doWrite(list);
outputStream.flush();
outputStream.close();
} catch (Exception e) {
// 重置response
response.reset();
response.setContentType("application/json");
response.setCharacterEncoding("utf-8");
Map<String, String> map = new HashMap<>();
map.put("status", "failure");
map.put("message", "下载文件失败" + e.getMessage());
e.printStackTrace();
}
}(2)测试结果
浏览器发起请求：http://localhost:8800/doWrite2
8、EasyExcel写入操作（批量写入）
既然我们在插入数据库的时候，有批量插入的功能，那么自然也可以实现批量写入excel的方式。这里我们就从数据库里将插入的数据再次读 取出来，放入一个新的excel表格中。
(1)Mapper文件
XML
<select id="selectCount" resultType="Integer">
select count(*) from t_book
</select>
<select id="selectBatch" resultType="com.example.yht.entity.Book" parameterType="map">
select
publish_date as publishDate,
book_name as bookName,
author as author,
price as price,
sale_num as saleNum,
status as status
from t_book limit ${limitVal} offset ${offsetVal}
</select>
java
Integer selectCount();
List<Book> selectBatch(Map<String, Object> map);(2)编写Service
java
Integer selectCount();
List<Book> selectBatch(Map<String, Object> map);
java
@Override
public Integer selectCount() {
return bookMapper.selectCount();
}
@Override
public List<Book> selectBatch(Map<String, Object> map) {
return bookMapper.selectBatch(map);
}(3)Controller层
这里为了验证批量插入的效果，在每次读取之后，写入不同的sheet。
java
@GetMapping("/doWriteBatch")
public void downloadBatch(HttpServletResponse response){
// 数据的总量(要写入Excel文件中的数据)
int count = bookService.selectCount();
int batchCount = 5;
List<Book> dataList = new ArrayList<>(batchCount);
// 总Sheet数
int num = count / batchCount;
// 输出流
OutputStream outputStream = null;
try {
response.setCharacterEncoding("UTF-8");
String excelName = URLEncoder.encode("batch_book", "UTF-8");
response.setHeader("Content-disposition", "attachment;filename=" + excelName + ".xlsx");
// 以字节流的形式输出响应正文
outputStream = response.getOutputStream();
try (ExcelWriter excelWriter = EasyExcel.write(outputStream, Book.class).build()) {
// 调用写入
for (int i = 0; i <= num; i++) {
// 每次写入都要创建WriteSheet, 这里注意必须指定sheetNo, 并且sheetName必须不一样
Map<String, Object> queryMap = new HashMap<>();
queryMap.put("limitVal", batchCount);
queryMap.put("offsetVal", i * batchCount);
WriteSheet writeSheet = EasyExcel.writerSheet(i, "batch" + (i + 1)).build();
dataList = bookService.selectBatch(queryMap);
System.out.println(dataList);
excelWriter.write(dataList, writeSheet);
}
}
// 清空集合
dataList.clear();
} catch (IOException ex) {
throw new RuntimeException(ex);
} finally {
if (outputStream != null) {
try {
outputStream.close();
} catch (IOException ex) {
throw new RuntimeException(ex);
}
}
}
}(4)测试结果
请求：http://localhost:8800/doWriteBatch
