Java easyexcel使用教程之导出篇

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

<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>easyexcel</artifactId>
  <version>2.2.10</version>
</dependency>
<dependency>
  <groupId>org.apache.poi</groupId>
  <artifactId>poi</artifactId>
  <version>3.17</version>
</dependency>
<dependency>
  <groupId>org.apache.poi</groupId>
  <artifactId>poi-ooxml</artifactId>
  <version>3.17</version>
</dependency>
<dependency>
  <groupId>org.projectlombok</groupId>
  <artifactId>lombok</artifactId>
  <scope>provided</scope>
</dependency>
<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <scope>provided</scope>
  <version>4.12</version>
</dependency>

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<Student> generateStudent(int size) {
      List<Student> 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<ExcelWriter> 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<ExcelWriter> 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<Integer> {

  @Override
  public Class<Integer> 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<String> 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<ExcelWriter> 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<BigDecimal> {

  @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<ExcelWriter> 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<ExcelWriter> 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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原文链接：https://blog.csdn.net/cxj443914930/article/details/123538144