1. 引入pom依赖

         <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>easyexcel</artifactId>
        </dependency>

2. 实现功能

    结合Vue前端，实现浏览器页面直接导出日志文件
    实现文件的灵活导入
   

文件导出
3. 实体类

实体类里有自定义转换器：用于Java类型数据和Excel类型数据的转换，非常使用。结合注解，可以非常方便的进行Excel文件导出。

/**
 * <p>
 * 操作日志信息
 * </p>
 *
 * home.php?mod=space&uid=686208 horse
 * home.php?mod=space&uid=441028 2020-09-08
 * 注意: 实体类中如果使用@Accessory（chain=true）,那么导入的数据无法填充到实例中,导出数据不受影响
 */
@Data
@EqualsAndHashCode(callSuper = false)
@TableName("tb_operational_log")
@ApiModel(value = "OperationalLog对象", description = "操作日志信息")
public class OperationalLog implements Serializable {

    private static final long serialVersionUID = 1L;

    @ExcelProperty({"操作日志", "日志ID"})
    @ApiModelProperty(value = "日志ID")
    @TableId(value = "id", type = IdType.ASSIGN_ID)
    private String id;

    @ExcelProperty({"操作日志", "操作类型"})
    @ApiModelProperty(value = "操作类型")
    private String operType;

    @ExcelProperty({"操作日志", "操作描述"})
    @ApiModelProperty(value = "操作描述")
    private String operDesc;

    @ExcelProperty({"操作日志", "操作员ID"})
    @ApiModelProperty(value = "操作员ID")
    private String operUserId;

    @ExcelProperty({"操作日志", "操作员名称"})
    @ApiModelProperty(value = "操作员名称")
    private String operUserName;

    @ExcelProperty({"操作日志", "操作方法"})
    @ApiModelProperty(value = "操作方法")
    private String operMethod;

    @ExcelProperty({"操作日志", "请求方法"})
    @ApiModelProperty(value = "请求方法")
    private String operRequWay;

    @ExcelProperty(value = {"操作日志", "请求耗时：单位-ms"}, converter = CustomRequestTimeConverter.class)
    @ApiModelProperty(value = "请求耗时：单位-ms")
    private Long operRequTime;

    @ExcelProperty({"操作日志", "请求参数"})
    @ApiModelProperty(value = "请求参数")
    private String operRequParams;

    @ExcelProperty({"操作日志", "请求Body"})
    @ApiModelProperty(value = "请求Body")
    private String operRequBody;

    @ExcelProperty({"操作日志", "请求IP"})
    @ApiModelProperty(value = "请求IP")
    private String operRequIp;

    @ExcelProperty({"操作日志", "请求URL"})
    @ApiModelProperty(value = "请求URL")
    private String operRequUrl;

    @ExcelProperty(value = {"操作日志", "日志标识"}, converter = CustomLogFlagConverter.class)
    @ApiModelProperty(value = "日志标识: 1-admin,0-portal")
    private Boolean logFlag;

    @ExcelProperty({"操作日志", "操作状态"})
    @ApiModelProperty(value = "操作状态:1-成功,0-失败")
    @TableField(value = "is_success")
    private Boolean success;

    @ExcelIgnore
    @ApiModelProperty(value = "逻辑删除 1-未删除， 0-删除")
    @TableField(value = "is_deleted")
    @TableLogic(value = "1", delval = "0")
    private Boolean deleted;

    @ExcelProperty(value = {"操作日志", "创建时间"}, converter = CustomTimeFormatConverter.class)
    @ApiModelProperty(value = "创建时间")
    private Date gmtCreate;
}

4. 接口和具体实现
   4.1 接口

    @OperatingLog(operType = BlogConstants.EXPORT, operDesc = "导出操作日志,写出到响应流中")
    @ApiOperation(value = "导出操作日志", hidden = true)
    @PostMapping("/oper/export")
    public void operLogExport(@RequestBody List<String> logIds, HttpServletResponse response) {
        operationalLogService.operLogExport(logIds, response);
    }

4.2 具体实现

    自定义导出策略HorizontalCellStyleStrategy
    自定义导出拦截器CellWriteHandler，更加精确的自定义导出策略

    /**
     * 导出操作日志(可以考虑分页导出)
     *
     * @param logIds
     * @param response
     */
    @Override
    public void operLogExport(List<String> logIds, HttpServletResponse response) {
        OutputStream outputStream = null;
        try {
            List<OperationalLog> operationalLogs;
            LambdaQueryWrapper<OperationalLog> queryWrapper = new LambdaQueryWrapper<OperationalLog>()
                    .orderByDesc(OperationalLog::getGmtCreate);
            // 如果logIds不为null,按照id查询信息,否则查询全部
            if (!CollectionUtils.isEmpty(logIds)) {
                operationalLogs = this.listByIds(logIds);
            } else {
                operationalLogs = this.list(queryWrapper);
            }
            outputStream = response.getOutputStream();

            // 获取单元格样式
            HorizontalCellStyleStrategy strategy = MyCellStyleStrategy.getHorizontalCellStyleStrategy();

            // 写入响应输出流数据
            EasyExcel.write(outputStream, OperationalLog.class).excelType(ExcelTypeEnum.XLSX).sheet("操作信息日志")
                    // .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()) // 自适应列宽(不是很适应,效果并不佳)
                    .registerWriteHandler(strategy) // 注册上面设置的格式策略
                    .registerWriteHandler(new CustomCellWriteHandler()) // 设置自定义格式策略
                    .doWrite(operationalLogs);
        } catch (Exception e) {
            log.error(ExceptionUtils.getMessage(e));
            throw new BlogException(ResultCodeEnum.EXCEL_DATA_EXPORT_ERROR);
        } finally {
            IoUtil.close(outputStream);
        }
    }

自定义导出策略简单如下：

/**
 * @author Mr.Horse
 * @version 1.0
 * @description: 单元格样式策略
 * @date 2021/4/30 8:43
 */

public class MyCellStyleStrategy {

    /**
     * 设置单元格样式(仅用于测试)
     *
     * @return 样式策略
     */
    public static HorizontalCellStyleStrategy getHorizontalCellStyleStrategy() {
        // 表头策略
        WriteCellStyle headerCellStyle = new WriteCellStyle();
        // 表头水平对齐居中
        headerCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);
        // 背景色
        headerCellStyle.setFillForegroundColor(IndexedColors.SKY_BLUE.getIndex());
        WriteFont headerFont = new WriteFont();
        headerFont.setFontHeightInPoints((short) 14);
        headerCellStyle.setWriteFont(headerFont);
        // 自动换行
        headerCellStyle.setWrapped(Boolean.FALSE);

        // 内容策略
        WriteCellStyle contentCellStyle = new WriteCellStyle();
        // 设置数据允许的数据格式,这里49代表所有可以都允许设置
        contentCellStyle.setDataFormat((short) 49);
        // 设置背景色: 需要指定 FillPatternType 为FillPatternType.SOLID_FOREGROUND 不然无法显示背景颜色.头默认了 FillPatternType所以可以不指定
        contentCellStyle.setFillPatternType(FillPatternType.SOLID_FOREGROUND);
        contentCellStyle.setFillForegroundColor(IndexedColors.GREY_40_PERCENT.getIndex());
        // 设置内容靠左对齐
        contentCellStyle.setHorizontalAlignment(HorizontalAlignment.LEFT);
        // 设置字体
        WriteFont contentFont = new WriteFont();
        contentFont.setFontHeightInPoints((short) 12);
        contentCellStyle.setWriteFont(contentFont);
        // 设置自动换行
        contentCellStyle.setWrapped(Boolean.FALSE);
        // 设置边框样式和颜色
        contentCellStyle.setBorderLeft(MEDIUM);
        contentCellStyle.setBorderTop(MEDIUM);
        contentCellStyle.setBorderRight(MEDIUM);
        contentCellStyle.setBorderBottom(MEDIUM);
        contentCellStyle.setTopBorderColor(IndexedColors.RED.getIndex());
        contentCellStyle.setBottomBorderColor(IndexedColors.GREEN.getIndex());
        contentCellStyle.setLeftBorderColor(IndexedColors.YELLOW.getIndex());
        contentCellStyle.setRightBorderColor(IndexedColors.ORANGE.getIndex());

        // 将格式加入单元格样式策略
        return new HorizontalCellStyleStrategy(headerCellStyle, contentCellStyle);
    }
}

自定义导出拦截器简单如下：

/**
 * @author Mr.Horse
 * @version 1.0
 * @description 实现CellWriteHandler接口, 实现对单元格样式的精确控制
 * @date 2021/4/29 21:11
 */
public class CustomCellWriteHandler implements CellWriteHandler {

    private static Logger logger = LoggerFactory.getLogger(CustomCellWriteHandler.class);

    @Override
    public void beforeCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row,
                                 Head head, Integer columnIndex, Integer relativeRowIndex, Boolean isHead) {

    }

    /**
     * 单元格创建之后(没有写入值)
     *
     * @param writeSheetHolder
     * @param writeTableHolder
     * @param cell
     * @param head
     * @param relativeRowIndex
     * @param isHead
     */
    @Override
    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell,
                                Head head, Integer relativeRowIndex, Boolean isHead) {

    }

    @Override
    public void afterCellDataConverted(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder,
                                       CellData cellData, Cell cell, Head head, Integer relativeRowIndex,
                                       Boolean isHead) {

    }

    /**
     * 单元格处理后(已写入值): 设置第一行第一列的头超链接到EasyExcel的官网(本系统的导出的excel 0,1两行都是头,所以只设置第一行的超链接)
     * 这里再进行拦截的单元格样式设置的话,前面该样式将全部失效
     *
     * @param writeSheetHolder
     * @param writeTableHolder
     * @param cellDataList
     * @param cell
     * @param head
     * @param relativeRowIndex
     * @param isHead
     */
    @Override
    public void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder,
                                 List<CellData> cellDataList, Cell cell, Head head, Integer relativeRowIndex,
                                 Boolean isHead) {
        // 设置超链接
        if (isHead && cell.getRowIndex() == 0 && cell.getColumnIndex() == 0) {
            logger.info(" ==> 第{}行,第{}列超链接设置完成", cell.getRowIndex(), cell.getColumnIndex());
            CreationHelper helper = writeSheetHolder.getSheet().getWorkbook().getCreationHelper();
            Hyperlink hyperlink = helper.createHyperlink(HyperlinkType.URL);
            hyperlink.setAddress("https://github.com/alibaba/easyexcel");
            cell.setHyperlink(hyperlink);
        }
        // 精确设置单元格格式
        boolean bool = isHead && cell.getRowIndex() == 1 &&
                (cell.getStringCellValue().equals("请求参数") || cell.getStringCellValue().equals("请求Body"));
        if (bool) {
            logger.info("第{}行，第{}列单元格样式设置完成。", cell.getRowIndex(), cell.getColumnIndex());
            // 获取工作簿
            Workbook workbook = writeSheetHolder.getSheet().getWorkbook();
            CellStyle cellStyle = workbook.createCellStyle();

            Font cellFont = workbook.createFont();
            cellFont.setBold(Boolean.TRUE);
            cellFont.setFontHeightInPoints((short) 14);
            cellFont.setColor(IndexedColors.SEA_GREEN.getIndex());
            cellStyle.setFont(cellFont);
            cell.setCellStyle(cellStyle);
        }
    }
}

4.3 前端请求

前端在基于Vue+Element的基础上实现了点击导出按钮，在浏览器页面进行下载。

// 批量导出
    batchExport() {
      // 遍历获取id集合列表
      const logIds = []
      this.multipleSelection.forEach(item => {
        logIds.push(item.id)
      })
       // 请求后端接口
      axios({
        url: this.BASE_API + '/admin/blog/log/oper/export',
        method: 'post',
        data: logIds,
        responseType: 'arraybuffer',
        headers: { 'token': getToken() }
      }).then(response => {
        // type类型可以设置为文本类型，这里是新版excel类型
        const blob = new Blob([response.data], { type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;charset=utf-8' })
        const pdfUrl = window.URL.createObjectURL(blob)
        const fileName = 'HorseBlog操作日志' // 下载文件的名字
        // 对于<a>标签，只有 Firefox 和 Chrome（内核）支持 download 属性
        if ('download' in document.createElement('a')) {
          const link = document.createElement('a')
          link.href = pdfUrl
          link.setAttribute('download', fileName)
          document.body.appendChild(link)
          link.click()
          window.URL.revokeObjectURL(pdfUrl) // 释放URL 对象
        } else {
          // IE 浏览器兼容方法
          window.navigator.msSaveBlob(blob, fileName)
        }
      })
    }

测试结果：还行，基本实现了页面下载的功能
Excel文件导入
5. 文件读取配置

本配置基于泛型的方式编写，可扩展性较强。

/**
 * @author Mr.Horse
 * @version 1.0
 * @description: EasyExcel文件读取配置(不能让spring管理)
 * @date 2021/4/27 13:24
 */

public class MyExcelImportConfig<T> extends AnalysisEventListener<T> {

    private static Logger logger = LoggerFactory.getLogger(MyExcelImportConfig.class);

    /**
     * 每次读取的最大数据条数
     */
    private static final int MAX_BATCH_COUNT = 10;

    /**
     * 泛型bean属性
     */
    private T dynamicService;

    /**
     * 可接收任何参数的泛型List集合
     */
    List<T> list = new ArrayList<>();

    /**
     * 构造函数注入bean(根据传入的bean动态注入)
     *
     * @param dynamicService
     */
    public MyExcelImportConfig(T dynamicService) {
        this.dynamicService = dynamicService;
    }

    /**
     * 解析每条数据都进行调用
     *
     * @param data
     * @param context
     */
    @Override
    public void invoke(T data, AnalysisContext context) {
        logger.info(" ==> 解析一条数据: {}", JacksonUtils.objToString(data));
        list.add(data);
        if (list.size() > MAX_BATCH_COUNT) {
            // 保存数据
            saveData();
            // 清空list
            list.clear();
        }
    }

    /**
     * 所有数据解析完成后,会来调用一次
     * 作用: 避免最后集合中小于 MAX_BATCH_COUNT 条的数据没有被保存
     *
     * @param context
     */
    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {
        saveData();
        logger.info(" ==> 数据解析完成 <==");
    }

    /**
     * 保存数据: 正式应该插入数据库,这里用于测试
     */
    private void saveData() {
        logger.info(" ==> 数据保存开始: {}", list.size());
        list.forEach(System.out::println);
        logger.info(" ==> 数据保存结束 <==");
    }

    /**
     * 在转换异常 获取其他异常下会调用本接口。我们如果捕捉并手动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。
     *
     * @param exception
     * @param context
     * @throws Exception
     */
    @Override
    public void onException(Exception exception, AnalysisContext context) throws Exception {
        logger.error(" ==> 数据解析失败,但是继续读取下一行:{}", exception.getMessage());
        //  如果是某一个单元格的转换异常 能获取到具体行号
        if (exception instanceof ExcelDataConvertException) {
            ExcelDataConvertException convertException = (ExcelDataConvertException) exception;
            logger.error("第{}行，第{}列数据解析异常", convertException.getRowIndex(), convertException.getColumnIndex());
        }
    }

}

6. 读取测试

    @ApiOperation(value = "数据导入测试", notes = "操作日志导入测试[OperationalLog]", hidden = true)
    @PostMapping("/import")
    public R excelImport(@RequestParam("file") MultipartFile file) throws IOException {
        EasyExcel.read(file.getInputStream(), OperationalLog.class, new MyExcelImportConfig<>(operationalLogService))
                .sheet().doRead();
        return R.ok().message("文件导入成功");
    }

7. 附上自定义属性转换器

   转换器的属性内容转换，需要根据自己的实际业务需求而定，这里仅作为简单示例

/**
 * @author Mr.Horse
 * @version 1.0
 * @description: 自定义excel转换器: 将操作日志的请求耗时加上单位 "ms"
 * @date 2021/4/27 10:25
 */

public class CustomRequestTimeConverter implements Converter<Long> {

    /**
     * 读取数据时: 属性对应的java数据类型
     *
     * @return
     */
    @Override
    public Class<Long> supportJavaTypeKey() {
        return Long.class;
    }

    /**
     * 写入数据时: excel内部的数据类型,因为请求耗时是long类型,对应excel是NUMBER类型,但是加上"ms后对应的是STRING类型"
     *
     * @return
     */
    @Override
    public CellDataTypeEnum supportExcelTypeKey() {
        return CellDataTypeEnum.STRING;
    }

    /**
     * 读取回调
     *
     * @param cellData
     * @param contentProperty
     * @param globalConfiguration
     * @return
     * @throws Exception
     */
    @Override
    public Long convertToJavaData(CellData cellData, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) throws Exception {
        // 截取字符串: "ms",转换为long类型
        String value = cellData.getStringValue();
        return Long.valueOf(value.substring(0, value.length() - 2));
    }

    @Override
    public CellData<Long> convertToExcelData(Long value, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) throws Exception {
        // 添加字符串: "ms"
        return new CellData<>(String.valueOf(value).concat("ms"));
    }
}

格式化时间

/**
 * @author Mr.Horse
 * @version 1.0
 * @description: {description}
 * @date 2021/4/27 14:01
 */

public class CustomTimeFormatConverter implements Converter<Date> {

    @Override
    public Class<Date> supportJavaTypeKey() {
        return Date.class;
    }

    @Override
    public CellDataTypeEnum supportExcelTypeKey() {
        return CellDataTypeEnum.STRING;
    }

    @Override
    public Date convertToJavaData(CellData cellData, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) throws Exception {
        String value = cellData.getStringValue();
        return DateUtil.parse(value, DatePattern.NORM_DATETIME_PATTERN);
    }

    @Override
    public CellData<Date> convertToExcelData(Date value, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) throws Exception {
        return new CellData<>(DateUtil.format(value, DatePattern.NORM_DATETIME_PATTERN));
    }
}