EasyExcel custom Converter solves the problem of localDateTime series time and date conversion

I. Introduction

        The LocalDateTime series is a brand-new operation class provided by jdk8 for date and time processing. Compared with the Date class, it has been greatly improved. For details, refer to the link at the end.

        Therefore, the processing of time and date in the project is gradually replaced by LocalDateTime. EasyExcel comes with DateStringConverter for Date data type conversion, but the LocalDateTime series does not, so write this custom data format converter. 

2. Custom Converter

import com.alibaba.excel.converters.Converter;
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;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

/**
 * @Author gmd
 * @Description EasyExcel自定义LocalDateTime系列时间日期转换器
 * 用法：
 *      1、@ExcelProperty(value = {"添加时间"}, converter = BaseDateConverter.LocalDateTimeConverter.class)
 *      2、ExcelWriter writer = EasyExcel.write(response.getOutputStream()).registerConverter(new BaseDateConverter.LocalDateConverter()).build();
 * @Date 2022-08-31 19:23:08
 */
public class BaseDateConverter {

    /**
     * 核心抽象类，负责不同类的数据类型装换
     * @param <T> LocalXXX类泛型
     */
    private static abstract class CoreConverter<T> implements Converter<T> {

        private Class<T> clazz;

        /**
         * 指定Class类型，接收LocalDate.class，LocalTime.class，LocalDateTime.class
         */
        public CoreConverter(Class<T> clazz) {
            this.clazz = clazz;
        }

        /**
         * 导入支持的数据类型
         */
        @Override
        public CellDataTypeEnum supportExcelTypeKey() {
            return CellDataTypeEnum.STRING;
        }

        /**
         * 导出支持的数据类型
         */
        @Override
        public Class supportJavaTypeKey() {
            return clazz;
        }

        /**
         * 导入时，数据类型转换
         * @param cellData excel单元格数据
         * @param property 单元格样式
         * @param config 全局配置
         * @return
         */
        @Override
        public T convertToJavaData(ReadCellData<?> cellData, ExcelContentProperty property, GlobalConfiguration config) throws Exception {
            // LocalDate日期转换
            if (cellData.getData() instanceof LocalDate) {
                return (T) LocalDate.parse(cellData.getStringValue(), DateTimeFormatter.ofPattern("yyyy-MM-dd"));

                // LocalTime时间转换
            } else if (cellData.getData() instanceof LocalTime) {
                return (T) LocalTime.parse(cellData.getStringValue(), DateTimeFormatter.ofPattern("HH:mm:ss"));

                // LocalDateTime时间日期转换
            } else if (cellData.getData() instanceof LocalDateTime) {
                return (T) LocalDateTime.parse(cellData.getStringValue(), DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
            }
            return null;
        }

        /**
         * 导出时，数据类型转换
         * @param obj 当前数据
         * @param property 单元格样式
         * @param config 全局配置
         * @return
         */
        @Override
        public WriteCellData<?> convertToExcelData(T obj, ExcelContentProperty property, GlobalConfiguration config) throws Exception {
            // LocalDate日期转换
            if (obj instanceof LocalDate) {
                return new WriteCellData<>(((LocalDate) obj).format(DateTimeFormatter.ofPattern("yyyy-MM-dd")));

                // LocalTime时间转换
            } else if (obj instanceof LocalTime) {
                return new WriteCellData<>(((LocalTime) obj).format(DateTimeFormatter.ofPattern("HH:mm:ss")));

                // LocalDateTime时间日期转换
            } else if (obj instanceof LocalDateTime) {
                return new WriteCellData<>(((LocalDateTime) obj).format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
            }

            return new WriteCellData<>(obj.toString());
        }
    }

    /**
     * LocalDate数据类型转换器
     */
    public static class LocalDateConverter extends CoreConverter<LocalDate> {
        public LocalDateConverter() {
            super(LocalDate.class);
        }
    }

    /**
     * LocalTime数据类型转换器
     */
    public static class LocalTimeConverter extends CoreConverter<LocalTime> {
        public LocalTimeConverter() {
            super(LocalTime.class);
        }
    }

    /**
     * LocalDateTime数据类型转换器
     */
    public static class LocalDateTimeConverter extends CoreConverter<LocalDateTime> {
        public LocalDateTimeConverter() {
            super(LocalDateTime.class);
        }
    }

}

3. Usage

Usage one:

public class ReserveExcelVO {

    @ExcelProperty(value = {"添加日期"}, converter = BaseDateConverter.LocalDateTimeConverter.class)
    private LocalDate createTime;

}

Usage two:

// 设置excel表格样式
ExcelWriter writer = EasyExcel.write(response.getOutputStream()).needHead(true).excelType(ExcelTypeEnum.XLSX)
          .registerConverter(new BaseDateConverter.LocalDateConverter())
          .build();

Four. Postscript

The mapping relationship between the JDBC time date data type and the Java time date data type is also given here

Java Type	JDBC Type	illustrate
LocalDate	DATE	<result property="a" column="a" jdbcType="DATE"/>
LocalTime	TIME	<result property="a" column="a" jdbcType="TIME"/>
LocalDateTime	TIMESTAMP	<result property="a" column="a" jdbcType="TIMESTAMP"/>
Date	DATE or TIME or TIMESTAMP	/

Reference documents:

Comparison between java8 LocalDate, LocalTime, LocalDateTime and Date In actual use, LocalDate is used to calculate the date, and LocalDateTime is used to calculate the date plus time. If there is only time, it is LocalDateTime1 to obtain the current time object LocalDateTime localDateTime = Local... https://blog.csdn.net/LETIAN_Z/article/details/ 101522476 What are the types of jdbctype_IT Q&A Center_Ujiuye Employment (ujiuye.com) http://www.ujiuye.com/wenda/2021/71003.html