EasyExcel简介
EasyExcel是一个基于Java的简单、省内存的读写Excel的开源项目。在尽可能节约内存的情况下支持读写百M的Excel。
Excel解析流程图:
EasyExcel读取Excel的解析原理:
开始准备工作
1、导入Maven依赖
com.alibaba easyexcel 2.2.10 org.apache.poi poi 3.17 org.apache.poi poi-ooxml 3.17 org.projectlombok lombok provided junit junit provided 4.12
2、新建Student.java类
package com.test.easyexcel.bean;
import com.alibaba.excel.annotation.ExcelIgnoreUnannotated;
import com.alibaba.excel.annotation.ExcelProperty;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import java.math.BigDecimal;
import java.util.Date;
@Data
@ToString
@AllArgsConstructor
@NoArgsConstructor // 一定要有无参构造方法
public class Student {
@ExcelProperty(value = "姓名")
private String name;
@ExcelProperty(value = "性别")
private Integer sex;
@ExcelProperty(value = "生日")
private Date birthday;
@ExcelProperty(value = "体重KG")
private BigDecimal weight;
private String memo;
}
3、generateStudentUtil.java类，随机生成Student对象
package com.test.easyexcel.util;
import com.test.easyexcel.bean.Student;
import java.math.BigDecimal;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
public class generateStudentUtil {
public static List generateStudent(int size) {
List stues = new ArrayList<>();
for (int i = 0; i < size; i++) {
stues.add(new Student("姓名" + i, (int) (Math.random() * 2), randomDate(), randomWeight(), "备注"));
}
return stues;
}
public static Date randomDate() {
LocalDateTime localDateTime = LocalDateTime.of(randomInt(1990, 2022), randomInt(1, 12), randomInt(1, 28), randomInt(0, 23), randomInt(0, 59), randomInt(0, 59), randomInt(0, 999));
ZonedDateTime zdt = localDateTime.atZone(ZoneId.systemDefault());
return Date.from(zdt.toInstant());
}
public static int randomInt(int min, int max) {
int de = max - min;
// 二进制长度
int bitCount = Integer.toBinaryString(de).length();
int ans = 0;
do {
ans = 0;
for (int i = 0; i < bitCount; i++) {
ans += random0_1() << i;
}
} while (ans > de);
return ans + min;
}
public static int random0_1() {
return (int) (Math.random() * 2);
}
public static BigDecimal randomWeight() {
return BigDecimal.valueOf((Math.random() * 10));
}
}
4、BaseTest.java
package com.test.easyexcel;
import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.ExcelWriter;
import com.alibaba.excel.write.style.column.LongestMatchColumnWidthStyleStrategy;
import java.util.function.Consumer;
// 父类
public class BaseTest {
/**
* 导出方法
*
* @param fileName 文件
* @param writerConsumer consumer
*/
public static void export(String fileName, Consumer writerConsumer) {
ExcelWriter writer = EasyExcel.write(fileName)
.registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())
.build();
writerConsumer.accept(writer);
writer.finish();
}
}
4、导出Excel报表
package com.test.easyexcel;
import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.ExcelWriter;
import com.test.easyexcel.bean.Student;
import org.junit.Test;
import java.util.function.Consumer;
import static com.test.easyexcel.util.generateStudentUtil.generateStudent;
public class TestEasyExcel extends BaseTest {
@Test
public void export1() {
Consumer consumer = writer -> {
writer.write(generateStudent(10), EasyExcel.writerSheet("学生信息")
.head(Student.class)
.build());
};
export("D:/报表.xlsx", consumer);
}
}
运行export1结果
5、把姓名格式化：1显示男，0显示女
新建SexConverter.java
package com.test.easyexcel.converter; import com.alibaba.excel.converters.Converter; import com.alibaba.excel.enums.CellDataTypeEnum; import com.alibaba.excel.metadata.CellData; import com.alibaba.excel.metadata.GlobalConfiguration; import com.alibaba.excel.metadata.property.ExcelContentProperty; public class SexConverter implements Converter{ @Override public Class supportJavaTypeKey() { return Integer.class; } @Override public CellDataTypeEnum supportExcelTypeKey() { return CellDataTypeEnum.STRING; } @Override public Integer convertToJavaData(CellData cellData, ExcelContentProperty excelContentProperty, GlobalConfiguration globalConfiguration) throws Exception { return "男".equals(cellData.getStringValue()) ? 1 : 0; } @Override public CellData convertToExcelData(Integer integer, ExcelContentProperty excelContentProperty, GlobalConfiguration globalConfiguration) throws Exception { return new CellData<>(integer.equals(1) ? "男" : "女"); } }
Student类sex属性注入SexConverter转换器
@ExcelProperty(value = "性别", converter = SexConverter.class) private Integer sex;
再次运行export1()单元测试
6、把体重保留2位小数
方法1，@NumberFormat 注解。修改Student类
@ExcelProperty(value = "体重KG")
@NumberFormat("0.##") // 会以字符串形式生成单元格，要计算的列不推荐
private BigDecimal weight;
运行export1()单元测试
方法2：@ContentStyle(dataFormat = 2) 注解 ，我们新建一个字段weight2
@ContentStyle(dataFormat = 2) private BigDecimal weight2;
运行export1()单元测试
方法3：利用**registerConverter(new BigDecimalConverter())**统一类型处理
/**
* 测试统一类型转换
*/
@Test
public void export2() {
Consumer consumer = writer -> {
writer.write(generateStudent(10), EasyExcel.writerSheet("学生信息")
.registerConverter(new BigDecimalConverter())
.head(Student.class)
.build());
};
export("D:/报表.xlsx", consumer);
}
BigDecimalConverter.java
package com.test.easyexcel.converter; import com.alibaba.excel.converters.Converter; import com.alibaba.excel.enums.CellDataTypeEnum; import com.alibaba.excel.metadata.CellData; import com.alibaba.excel.metadata.GlobalConfiguration; import com.alibaba.excel.metadata.property.ExcelContentProperty; import java.math.BigDecimal; import java.math.RoundingMode; public class BigDecimalConverter implements Converter{ @Override public Class supportJavaTypeKey() { return BigDecimal.class; } @Override public CellDataTypeEnum supportExcelTypeKey() { return CellDataTypeEnum.NUMBER; } @Override public BigDecimal convertToJavaData(CellData cellData, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) throws Exception { return cellData.getNumberValue(); } @Override public CellData convertToExcelData(BigDecimal value, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) throws Exception { return new CellData(value.setScale(2, RoundingMode.DOWN)); } }
7、过滤字段不生成excel
方式1：类上加注解 @ExcelIgnoreUnannotated，过滤属性没有@ExcelProperty注解的字段
@Data
@ToString
@AllArgsConstructor
@NoArgsConstructor // 一定要有无参构造方法
@ExcelIgnoreUnannotated
public class Student {
.....
}
方式2：指定字段加注解
@ExcelIgnore // demo2不生成excel private String demo2;
方式3：代码指定过滤字段, 同一个excel生成两个sheet分别过滤不同字段
/**
* 过滤字段
*/
@Test
public void exportExcludeColumn() {
Consumer consumer = writer ->
writer.write(generateStudent(10), EasyExcel.writerSheet(1, "学生信息")
.excludeColumnFiledNames(Arrays.asList("name", "sex")) // sheet1过滤姓名、性别
.head(Student.class)
.build());
consumer = consumer.andThen(writer ->
writer.write(generateStudent(10), EasyExcel.writerSheet(2, "学生信息2")
.excludeColumnFiledNames(Arrays.asList("birthday", "weight")) // sheet2过滤生日和体重
.head(Student.class)
.build()));
export("D:/报表.xlsx", consumer);
}
8、冻结列, 冻结姓名列
冻结列handler,FreezeNameHandler.java
package com.learning.easyexcel.converter;
import com.alibaba.excel.write.handler.SheetWriteHandler;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.metadata.holder.WriteWorkbookHolder;
import org.apache.poi.ss.usermodel.Sheet;
/**
* 冻结姓名列
*/
public class FreezeNameHandler implements SheetWriteHandler {
@Override
public void beforeSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
}
@Override
public void afterSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
// 获取到当前的sheet
Sheet sheet = writeSheetHolder.getSheet();
/**
*第一个参数：冻结的列数
*第二个参数：冻结的行数
*第三个参数：冻结后第一列的列号
*第四个参数：冻结后第一行的行号
**/
sheet.createFreezePane(1, 0, 1, 0);
}
}
注册handler
/**
* 冻结姓名列
*/
@Test
public void exportFreezeColumn() {
Consumer consumer = writer -> {
writer.write(generateStudent(10), EasyExcel.writerSheet("学生信息")
.registerWriteHandler(new FreezeNameHandler()) // 冻结姓名列
.head(Student.class)
.build());
};
export("D:/报表.xlsx", consumer);
}
总结
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