1 Introduction

Ali recently read and write open source excel project EasyExcel and fire up. The original project was started to maintain, and update from 1.x to 2.x, and it quickly iterations, it has been updated to 2.1.0-beta3 version.

About easyexcel, its primary purpose is to reduce the loss of memory when reading excel , to simplify the write of excel api .

Meanwhile 2.x version offers many new features, you can direct specific reference to the official description of it, to write very detailed (Chinese) on the document github, there is not much to complain spread some of the necessary two or three hand knowledge of it, and now the project has constantly iteration, a contributor to the star also necessary:. smile:

Official Address: easyexcel warehouse address , easyexcel official website

Here I based easyexcel 2.0.5version encapsulates a simple tool to read and write excel in class web , mainly encapsulates the following functions:

By custom annotations LocalDateTimewrite format
By custom annotations enumeration type write format
Custom BaseExcelListenerabstract class encapsulates common data processing logic, supplementary reading and recording a line number read error occurs during excel skipped.
The web of packaging write operation excel
... (follow-up will continue to update api package easyexcel offer hope to make easyexcel more easy.)

The main features are listed below as well as a related example, you can look directly at the source code, each method has a complete write notes, thought that it was okay if able to look at it, I just graduated not long after the chicken dishes point of a star chant: smile: .

Attach Source Address: github.com/aStudyMachi...

2. Feature

2.1 The establishment of a mapping table excel each row of data with the Java model

easyexcel embodiment java write excel model may be based, you may be used List<List<String>>to read and write excel embodiment, where I read and write operations using a java-based model embodiment, the correspondence of the data with the java class attributes of each column excel

Key notes: @ExcelProperty, @EnumFormat,@LocalDateTimeFormat

How to establish the specific mapping java annotations Excel table data model can refer to com.wukun.module.easyexcel.pojotwo models java classes in Orderthe class with the Userclass

/**
 * @author WuKun
 * @since 2019/10/09
 */
@Data
@AllArgsConstructor
@NoArgsConstructor //必须要保证无参构造方法存在,否则会报初始化对象失败
public class User {

    /**
     * {@code @ExcelIgnore} 用于标识该字段不用做excel读写过程中的数据转换
     */
    @ExcelIgnore
    private Integer userId;

    /**
     * <pre>
     * {@code @ExcelIgnore} 中的属性 不建议 index 和 name 同时用
     *
     * 要么一个对象统一只用index表示列号,
     * 例如 : {@code @ExcelProperty(index = 0)}
     *
     * 要么一个对象统一只用value去匹配列名
     * 例如 : {@code @ExcelProperty("姓名")}
     *
     * 用名字去匹配,这里需要注意,如果名字重复,会导致只有一个字段读取到数据
     * </pre>
     */
    @ExcelProperty("姓名")
    private String name;

    @ExcelProperty("年龄")
    private Integer age;

    @ExcelProperty("地址")
    private String address;

    /**
     * <pre>
     * {@code @EnumFormat} 注解 :
     *  作用 : 与 {@code @ExcelProperty(converter = EnumExcelConverter.class)} 搭配使用
     *         转换java枚举与excel中指定的内容
     *  属性 :
     *   - value : 要转换的枚举类class对象
     *   - fromExcel : 指定excel中用户输入的枚举值的名字的字符串形式,与toJavaEnum中指定的枚举值一一对应
     *                 以下面的示例来说,fromExcel指定的 "男" 对应 toJavaEnum中的 "MAN" ,
     *                 当excel中该列读取到"男" 这个字符串时,会自动转化为枚举{@code GenderEnum.MAN},
     *                 同理在写excel时,如果该字段为{@code GenderEnum.MAN} 时, 写到excel时则转化为 "男"
     *   - toJavaEnum : 如上所述
     *
     *  注意 : fromExcel 与 toJavaEnum 这两个属性必须同时使用, 而且两个属性的字符串的数组长度必须相同,
     *        若两个属性都不指定 , 则默认 枚举值名字符串转化为对应的枚举 例如: "MAN" <--> {@code GenderEnum.MAN}
     * </pre>
     */
    @EnumFormat(value = GenderEnum.class,
            fromExcel = {"男", "女"},
            toJavaEnum = {"MAN", "WOMAN"}) // "男" <--> GenderEnum.MAN ; "女" <--> GenderEnum.WOMAN
    @ExcelProperty(value = "性别", converter = EnumExcelConverter.class)
    private GenderEnum gender;

    /**
     * <pre>
     * {@code @LocalDateTimeFormat} 注解
     *  作用: 与 {@code  @ExcelProperty(converter = LocalDateTimeExcelConverter.class)} 搭配使用,
     *        指定导入导出的时间格式.
     *  属性 :
     *   - value : 日期格式字符串 
     * </pre>
     */
    @ExcelProperty(value = "生日", converter = LocalDateTimeExcelConverter.class)
    @LocalDateTimeFormat("yyyy-MM-dd HH:mm:ss")
    private LocalDateTime birthday;
}

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2.2 Export excel

2.2.1 Introduction API related

The web export excel 03/07 version is divided into two different methods, namely EasyExcelUtilthe class of the following two methods:

Export 03 Version: exportExcel2003Format(EasyExcelParams excelParams)
Export 07 Version: exportExcel2007Format(EasyExcelParams excelParams)

EasyExcelParamsEasyExcel derived using excel parameters to be set, including the need to export List<T>data and the corresponding Java model, set the parameters according to the actual situation of use.

/**
 * @author WuKun
 * @since 2019/10/14
 */
@Data
@EqualsAndHashCode(callSuper = false)
@Accessors(chain = true)
public class EasyExcelParams implements Serializable {


    /**
     * excel文件名（不带拓展名)
     */
    private String excelNameWithoutExt;
    /**
     * sheet名称
     */
    private String sheetName;

    /**
     * 数据
     */
    private List data;

    /**
     * 数据模型类型
     */
    private Class dataModelClazz;

    /**
     * 响应
     */
    private HttpServletResponse response;


    public EasyExcelParams() {
    }

    /**
     * 检查不允许为空的属性
     *
     * @return this
     */
    public EasyExcelParams checkValid() {
        Assert.isTrue(ObjectUtils.allNotNull(excelNameWithoutExt, data, dataModelClazz, response), "导出excel参数不合法!");
        return this;
    }
}
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2.2.2 Export excel example

/**
* 使用EasyExcelUtils 导出Excel 2007
*
* @param response HttpServletResponse
* @throws Exception exception
*/
@GetMapping("/easy2007")
public void easy2007(HttpServletResponse response) throws Exception {
    initData();

    //设置参数
    EasyExcelParams params = new EasyExcelParams().setResponse(response)
        .setExcelNameWithoutExt("Order(xlsx)")
        .setSheetName("第一张sheet")
        .setData(data)
        .setDataModelClazz(Order.class)
        .checkValid();

    long begin = System.currentTimeMillis();
    EasyExcelUtil.exportExcel2007(params);
    long end = System.currentTimeMillis();

    log.info("-----EasyExcelUtils : 导出成功,导出excel花费时间为 : " + ((end - begin) / 1000) + "秒");
}

private void initData() {
    if (CollectionUtils.isEmpty(data)) {
        for (int i = 0; i < 60000; i++) {
            data.add(new Order().setPrice(BigDecimal.valueOf(11.11))
                     .setCreateTime(LocalDateTime.now()).setGoodsName("香蕉")
                     .setOrderId(i)
                     .setNum(11)
                     .setOrderStatus(OrderStatusEnum.PAYED));
        }
    }
}
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2.3 Read excel

2.3.1 Introduction API related

It is used when reading excel EasyExcelUtilsthe readExcelmethod;

/**
 * 读取 Excel(支持单个model的多个sheet)
 *
 * @param excel    文件
 * @param rowModel 实体类映射
 * @param listener 用于读取excel的listener
 */
public static void readExcel(MultipartFile excel, Class rowModel, BaseExcelListener listener) {
    ExcelReader reader = getReader(excel, rowModel, listener);
    try {
        Assert.notNull(reader, "导入Excel失败!");
        Integer totalSheetCount = reader.getSheets().size();
        for (Integer i = 0; i < totalSheetCount; i++) {
            reader.read(EasyExcel.readSheet(i).build());
        }
    } finally {
        // 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
        Optional.ofNullable(reader).ifPresent(ExcelReader::finish);
    }
}
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easyexcel read operation requires a self class inherits AnalysisEventListenerthe abstract class, where I created BaseExcelListenerclass inherited and related methods excel rewrite read, the specific role of each method can directly view the method header comments, create a listener class directly use Inheritance BaseExcelListenercan be, if the default BaseExcelListenerdoes not meet the requirements, you can also customize a direct Listener class inheritance BaseExcelListenerand override the appropriate methods.

/**
 * @author WuKun
 * @since 2019-10-10
 * <p>
 * 由于在实际中可能会根据不同的业务场景需要的读取到的不同的excel表的数据进行不同操作,
 * 所以这里将{@link BaseExcelListener}作为所有listener的父类,根据读取不同的java模型自定义一个listener类继承{@link BaseExcelListener},
 * 根据不同的业务场景选择性对以下方法进行重写,具体如{@link OrderListener}所示
 * </p>
 *
 * <p>如果默认实现的方法不满足业务,则直接自定义一个listener继承{@link BaseExcelListener},重写一遍方法即可.</p>
 */
@Slf4j
public abstract class BaseExcelListener<Model> extends AnalysisEventListener<Model> {

    /**
     * 每隔N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 = 3000;

    /**
     * 自定义用于暂时存储data。
     * 可以通过实例获取该值
     * 可以指定AnalysisEventListener的泛型来确定List的存储类型
     */
    @Getter
    private List<Model> data = new ArrayList<>();

    /**
     * 读取时抛出异常是否继续读取,默认true,表示跳过错误行继续读取
     */
    @Setter
    private boolean continueAfterThrowing = true;


    /**
     * 读取过程中发生异常被跳过的行数记录
     * String 为 sheetNo
     * List<Integer> 为 错误的行数列表
     */
    @Getter
    private Map<String, List<Integer>> errRowsMap = new HashMap<>();

    /**
     * 每解析一行会回调invoke()方法。
     * 如果当前行无数据,该方法不会执行,
     * 也就是说如果导入的的excel表无数据,该方法不会执行,
     * 不需要对上传的Excel表进行数据非空判断
     *
     * @param object  当前读取到的行数据对应的java模型对象
     * @param context 定义了获取读取excel相关属性的方法
     */
    @Override
    public void invoke(Model object, AnalysisContext context) {
        log.info("解析到一条数据:{}", object);
        // 数据存储到list，供批量处理，或后续自己业务逻辑处理。
        data.add(object);

        //如果continueAfterThrowing 为false 时保证数据插入的一致性
        if (data.size() >= BATCH_COUNT && continueAfterThrowing) {
            saveData();
            data.clear();
        }
    }

    /**
     * 入库,继承该类后实现该方法即可
     */
    abstract void saveData();

    /**
     * 解析监听器
     * 每个sheet解析结束会执行该方法
     */
    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {
        saveData();
        log.info("/*------- 当前sheet读取完毕,sheetNo : {} , 读取错误的行号列表 : {} -------*/",
                getCurrentSheetNo(context), JSON.toJSONString(errRowsMap));
        data.clear();//解析结束销毁不用的资源
    }

    /**
     * 在转换异常 获取其他异常下会调用本接口。抛出异常则停止读取。如果这里不抛出异常则 继续读取下一行。
     * 如果不重写该方法,默认抛出异常,停止读取
     *
     * @param exception exception
     * @param context   context
     */
    @Override
    public void onException(Exception exception, AnalysisContext context) {
        if (!continueAfterThrowing) {
            throw new IllegalArgumentException(exception);
        }

        Integer sheetNo = getCurrentSheetNo(context);
        Integer rowIndex = context.readRowHolder().getRowIndex();
        log.error("/*------- 读取发生错误! 错误SheetNo:{},错误行号:{} -------*/ ", sheetNo, rowIndex, exception);

        List<Integer> errRowNumList = errRowsMap.get(String.valueOf(sheetNo));
        if (Objects.isNull(errRowNumList)) {
            errRowNumList = new ArrayList<>();
            errRowNumList.add(rowIndex);
            errRowsMap.put(String.valueOf(sheetNo), errRowNumList);
        } else {
            errRowNumList.add(rowIndex);
        }
    }

    /**
     * 获取当前读取的sheet no
     *
     * @param context
     * @return
     */
    private Integer getCurrentSheetNo(AnalysisContext context) {
        return context.readSheetHolder().getSheetNo();
    }

}
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03 or 07 does not distinguish between the read version, automatically determines the bottom;

Example 2.3.2 Read excel

Customizing a listener class inheritanceBaseExcelListener

package com.luwei.module.easyexcel.listener;

import com.wukun.module.easyexcel.pojo.User;
import lombok.extern.slf4j.Slf4j;

/**
 * @author WuKun
 * @since 2019/10/10
 */
@Slf4j
public class UserListener extends BaseExcelListener<User> {
    /**
     * 这里需要注意入库使用到的Service或者DAO层需要使用到的相关方法时,
     * 不要通过Spring 使用{@code @Autowired}注入,同时该Listener也不要交由Spring IOC进行管理
     * 直接通过构造方法传入相关`xxxService` 或者 `xxxMapper`
     */
    private UserService userService;

    public UserListener(UserService userService) {
        this.userService = userService;
    }
    
    @Override
    void saveData() {
        // 批量插入数据
        userService.saveBatchUsers(this.getData())
        log.info("/*------- 写入数据 -------*/");
    }
}
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Calling utility methods

@Autowired
private UserService userService;

/**
* 读取测试
*
* @param excel excel文件
*/
@PostMapping("/readExcel")
public void readExcel(@RequestParam MultipartFile excel) {
    EasyExcelUtil.readExcel(excel, User.class, new UserListener(userService));
}
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3. Notes

java model must ensure that there is no argument constructor method, otherwise it will not be an exception java object model initialization in reading and writing excel Times
~~Use java model can not be used when reading excel model for Java @Accessors(chain = true)annotations, can cause data can not be converted~~ (easyexcel 2.x API that this issue has been resolved)

sheetNo starting from 0, the row number does not include the header, for example, the log is printed line 9, corresponding to the actual excel in line 10 is

2019-10-20 15:34:57.236  INFO 38012 --- [nio-8081-exec-8] c.l.e.listener.BaseExcelListener         : /*------- 当前sheet读取完毕,sheetNo : 1 , 读取错误的行号列表 : {"1":[9]} -------*/
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