Article directory
EasyExcel documentation: https://www.yuque.com/easyexcel/doc/easyexcel
1.Maven imports the easyExcel package
<dependencies>
<!--easyExcel-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>easyexcel</artifactId>
<version>2.2.6</version>
</dependency>
<!--日期格式化工具-->
<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
<version>2.10.1</version>
</dependency>
<!--lombok-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.12</version>
</dependency>
<!--fastjson-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.71</version>
</dependency>
<!--测试-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
</dependencies>
2.easyExcel for basic writing
1. Create the corresponding entity class
package com.domain;
import com.alibaba.excel.annotation.ExcelIgnore;
import com.alibaba.excel.annotation.ExcelProperty;
import lombok.Data;
import java.util.Date;
/**
* @author: libo
* @date: 2020/10/12 11:36
* @motto: 即使再小的帆也能远航
*/
@Data
public class DemoData {
/*@ExcelProperty value = 标题(字段) index = 列数(可以直接选择第几列)*/
@ExcelProperty(value = "字符串标题", index = 0)
private String stringName;
@ExcelProperty(value = "日期标题", index = 1)
private Date dateName;
@ExcelProperty(value = "数字标题", index = 3)
private Double doubleName;
/*@ExcelIgnore在操作时忽略此字段*/
@ExcelIgnore
private int money;
}
2. The listener used by easyExcel (the following code is copied from the official one)
package com.utils;
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.alibaba.fastjson.JSON;
import com.dao.DemoDAO;
import com.domain.DemoData;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.List;
/**
* @author: libo
* @date: 2020/10/12 16:13
* @motto: 即使再小的帆也能远航
*/
// 有个很重要的点 DemoDataListener 不能被spring管理，要每次读取excel都要new,然后里面用到spring可以构造方法传进去
public class DemoDataListener extends AnalysisEventListener<DemoData> {
private static final Logger LOGGER = LoggerFactory.getLogger(DemoDataListener.class);
/**
* 每隔5条存储数据库，实际使用中可以3000条，然后清理list ，方便内存回收
*/
private static final int BATCH_COUNT = 5;
List<DemoData> list = new ArrayList<DemoData>();
/**
* 假设这个是一个DAO，当然有业务逻辑这个也可以是一个service。当然如果不用存储这个对象没用。
*/
private DemoDAO demoDAO;
public DemoDataListener() {
// 这里是demo，所以随便new一个。实际使用如果到了spring,请使用下面的有参构造函数
demoDAO = new DemoDAO();
}
/*如果使用了spring,请使用这个构造方法。每次创建Listener的时候需要把spring管理的类传进来
* @param demoDAO*/
public DemoDataListener(DemoDAO demoDAO) {
this.demoDAO = demoDAO;
}
/**
* 这个每一条数据解析都会来调用
*
* @param data one row value. Is is same as {@link AnalysisContext#readRowHolder()}
* @param context
*/
/*读取数据会执行 invoke 方法
* DemoData 数据的Beanl类
* AnalysisContext 分析上下文*/
@Override
public void invoke(DemoData data, AnalysisContext context) {
/*输出到控制台*/
System.out.println(JSON.toJSONString(data));
LOGGER.info("解析到一条数据:{}", JSON.toJSONString(data));
list.add(data);
// 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();
}
}
/*所有数据解析完成了 都会来调用
* @param context*/
@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();
LOGGER.info("所有数据解析完成！");
}
/*加上存储数据库*/
private void saveData() {
LOGGER.info("{}条数据，开始存储数据库！", list.size());
demoDAO.save(list);
LOGGER.info("存储数据库成功！");
}
}
If it needs to be stored in the database (add Dao class and method), the listener will call
public class DemoDAO {
public void save(List<DemoData> list) {
// 如果是mybatis,尽量别直接调用多次insert,自己写一个mapper里面新增一个方法batchInsert,所有数据一次性插入
}
3. Writing code: reading and writing
import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.ExcelReader;
import com.alibaba.excel.ExcelWriter;
import com.alibaba.excel.read.metadata.ReadSheet;
import com.alibaba.excel.write.metadata.WriteSheet;
import com.domain.DemoData;
import com.utils.DemoDataListener;
import org.junit.Test;
import java.io.File;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
/**
* @author: libo
* @date: 2020/10/12 11:31
* @motto: 即使再小的帆也能远航
*/
public class easyTest {
final String PATH = "D:\\IntelliJ IDEA 2019.1_File\\POIandEasyExcel\\easyExcel\\";
/*模拟数据来源*/
public List<DemoData> data() {
List<DemoData> list = new ArrayList<DemoData>();
/*循环10次,在Excel中就是10行数据*/
for (int x = 1; x < 11; x++) {
DemoData data = new DemoData();
/*字符串标题*/
data.setStringName("字符串" + x);
/*日期标题*/
data.setDateName(new Date());
/*数字标题*/
data.setDoubleName((double) x);
/*查看被忽略字段(标题)是否会被写入*/
data.setMoney(x);
/*添加进集合*/
list.add(data);
}
return list;
}
/*easyExcel写入数据*/
@Test
public void easyExcelWrite() {
/*写出文件路径*/
String fileName = PATH + "easyExcelTest.xlsx";
// 写法1(只需一行代码搞定)
// 这里 需要指定写用哪个class去写，然后写到第一个sheet，名字为模板 然后文件流会自动关闭
// 如果这里想使用03 则 传入excelType参数即可
/* 几个方法的参数解释：
write(1.路径,2.格式类)
sheet(Excel中的模板名称)
doWrite(数据)*/
EasyExcel.write(fileName, DemoData.class).sheet("easyExcel模板").doWrite(data());
// 写法2
// 这里 需要指定写用哪个class去写
ExcelWriter excelWriter = null;
try {
excelWriter = EasyExcel.write(fileName, DemoData.class).build();
WriteSheet writeSheet = EasyExcel.writerSheet("easyExcel模板").build();
excelWriter.write(data(), writeSheet);
} finally {
// 千万别忘记finish 会帮忙关闭流
if (excelWriter != null) {
excelWriter.finish();
}
}
}
/*easyExcel读取数据*/
@Test
public void easyExcelRead() {
/*写出文件路径*/
String fileName = PATH + "easyExcelTest.xlsx";
// 有个很重要的点 DemoDataListener 不能被spring管理，要每次读取excel都要new,然后里面用到spring可以构造方法传进去
// 写法1：
// 这里 需要指定读用哪个class去读，然后读取第一个sheet 文件流会自动关闭
// EasyExcel.read(fileName, DemoData.class, new DemoDataListener()).sheet().doRead();
// 写法2：
ExcelReader excelReader = null;
try {
excelReader = EasyExcel.read(fileName, DemoData.class, new DemoDataListener()).build();
ReadSheet readSheet = EasyExcel.readSheet(0).build();
excelReader.read(readSheet);
} finally {
if (excelReader != null) {
// 这里千万别忘记关闭，读的时候会创建临时文件，到时磁盘会崩的
excelReader.finish();
}
}
}
}
I won’t introduce too much about easyExcel, because the documentation is very clear and a demo has already been written. Compared with POI, easyExcel is simpler to operate and requires less code.
EasyExcel still uses POI internally.