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Java 导入导出 Excel

Java 导入导出 Excel

作者: 星辰大海w | 来源:发表于2019-01-04 16:40 被阅读0次

基于 alibaba/easyexcel,据称此项目基于 Apache POI 并解决了 OOM 问题。

  1. 导包
<!-- easyexcel -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>easyexcel</artifactId>
    <version>1.1.2-beta4</version>
</dependency>

经测试,发现此项目存在不满足需求之处:不支持在现有模板基础上,传入 list 覆盖表格已有的行,形成新文件

原因在于 com.alibaba.excel.write.ExcelBuilderImpl 中写入 List 数据时,先判断当前表格最后一行,在此行后面续写,保证已有的数据不会覆盖。

  1. 重新写一个 ExcelEditor 类实现 ExcelBuilder 接口

/**
 * 可以根据模板修改数据生成新表
 * 参考 com.alibaba.excel.write.ExcelBuilderImpl
 */
public class ExcelEditor implements ExcelBuilder {
    private WriteContext context;

    public ExcelEditor(InputStream inp, OutputStream out, ExcelTypeEnum excelType, boolean needHead) {
        try {
            POITempFile.createPOIFilesDirectory();
            this.context = new WriteContext(inp, out, excelType, needHead);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public void addContent(List data, int startRow) {
        // 允许覆盖已有行
        if (!CollectionUtils.isEmpty(data)) {
            for (int i = 0; i < data.size(); ++i) {
                int n = i + startRow + 1;
                this.addOneRowOfDataToExcel(data.get(i), n);
            }
        }
    }

    public void addContent(List data, Sheet sheetParam) {
        this.context.currentSheet(sheetParam);
        // 覆盖sheet名称
        this.context.getWorkbook().setSheetName(sheetParam.getSheetNo() - 1, sheetParam.getSheetName());
        this.addContent(data, sheetParam.getStartRow());
    }

    public void addContent(List data, Sheet sheetParam, Table table) {
        this.context.currentSheet(sheetParam);
        this.context.currentTable(table);
        this.addContent(data, sheetParam.getStartRow());
    }

    public void merge(int firstRow, int lastRow, int firstCol, int lastCol) {
        CellRangeAddress cra = new CellRangeAddress(firstRow, lastRow, firstCol, lastCol);
        this.context.getCurrentSheet().addMergedRegion(cra);
    }

    /**
     * 修改指定cell内容
     *
     * @param row     行号(起始于0)
     * @param col     列号(起始于0)
     * @param content 内容(字符串)
     */
    public void setCellValue(Integer row, Integer col, String content) {
        this.context.getCurrentSheet().getRow(row).getCell(col).setCellValue(content);
    }

    /**
     * 修改指定cell内容
     *
     * @param row     行号(起始于0)
     * @param col     列号(起始于0)
     * @param content 内容(日期)
     */
    public void setCellValue(Integer row, Integer col, Date content) {
        this.context.getCurrentSheet().getRow(row).getCell(col).setCellValue(content);
    }

    public void finish() {
        try {
            this.context.getWorkbook().write(this.context.getOutputStream());
            this.context.getWorkbook().close();
        } catch (IOException e) {
            throw new ExcelGenerateException("IO error", e);
        }
    }

    private void addBasicTypeToExcel(List oneRowData, Row row) {
        if (!CollectionUtils.isEmpty(oneRowData)) {
            for (int i = 0; i < oneRowData.size(); ++i) {
                Object cellValue = oneRowData.get(i);
                WorkBookUtil.createCell(row, i, this.context.getCurrentContentStyle(), cellValue, TypeUtil.isNum(cellValue));
            }
        }
    }

    private void addJavaObjectToExcel(Object oneRowData, Row row) {
        int i = 0;
        BeanMap beanMap = BeanMap.create(oneRowData);
        for (Iterator prop = this.context.getExcelHeadProperty().getColumnPropertyList().iterator(); prop.hasNext(); ++i) {
            ExcelColumnProperty excelHeadProperty = (ExcelColumnProperty) prop.next();
            String cellValue = TypeUtil.getFieldStringValue(beanMap, excelHeadProperty.getField().getName(), excelHeadProperty.getFormat());
            Boolean isNum = TypeUtil.isNum(excelHeadProperty.getField());
            // 覆盖已有单元格
            Cell cell = row.getCell(i);
            if (null == cell) {
                cell = row.createCell(i);
            }
            if (null != cellValue) {
                if (isNum) {
                    cell.setCellValue(Double.parseDouble(cellValue));
                } else {
                    cell.setCellValue(cellValue);
                }
            }
        }
    }

    private void addOneRowOfDataToExcel(Object oneRowData, int n) {
        org.apache.poi.ss.usermodel.Sheet sheet = this.context.getCurrentSheet();
        // 覆盖已有行
        Row row = sheet.getRow(n);
        if (null == row) {
            row = sheet.createRow(n);
        }
        if (oneRowData instanceof List) {
            this.addBasicTypeToExcel((List) oneRowData, row);
        } else {
            this.addJavaObjectToExcel(oneRowData, row);
        }
    }
}

  1. 编写 Excel 修改工具类,简化使用 ExcelEditor

/**
 * Excel工具类
 * 封装com.alibaba.excel
 * 封装com.company.ExcelEditor
 */
@Slf4j
public class ExcelUtil {
    /**
     * 读取指定路径excel到list
     *
     * @param path  文件路径
     * @param sheet sheet参数
     */
    public static List readExcel(String path, Sheet sheet) {
        try (InputStream inp = new ClassPathResource(path).getInputStream()) {
            return EasyExcelFactory.read(inp, sheet);
        } catch (Exception e) {
            log.warn("解析EXCEL文件异常:", e);
        }
        return Collections.EMPTY_LIST;
    }

    /**
     * 根据模板修改excel到OutputStream
     *
     * @param template  excel模板路径
     * @param out       输出流
     * @param excelType excel版本
     * @param consumer  处理逻辑
     */
    public static void editExcel(String template, OutputStream out, ExcelTypeEnum excelType, Consumer<ExcelEditor> consumer) {
        try (InputStream inp = new ClassPathResource(template).getInputStream()) {
            ExcelEditor editor = new ExcelEditor(inp, out, excelType, false);
            consumer.accept(editor);
            editor.finish();
            out.flush();
        } catch (Exception e) {
            log.warn("编辑EXCEL文件异常:", e);
        }
    }
}

  1. 测试 excel 修改
// 模板文件地址
String template = "template.xls";

// 模板sheet
Sheet sheet = new Sheet(1, 2, UserModel.class);
sheet.setStartRow(1);
sheet.setSheetName("sheet名称");

// 模板中已有行
List<UserModel> list = (List<UserModel>) ExcelUtil.readExcel(template, sheet);

// 修改list
for (UserModel model : list) {
    model.setName("测试")
}

// ServletOutputStream out = response.getOutputStream();
OutputStream out = new FileOutputStream("bbbb.xlsx");
// 输出excel
ExcelUtil.editExcel(template, out, ExcelTypeEnum.XLS, editor -> {
    // 用list覆盖数据
    editor.addContent(list, sheet);
    // 设置指定单元格
    editor.setCellValue(1, 2, "测试单元格");
});

经测试:
对于 XLS 格式的模板读写成功。
对于已有数据的行可以覆盖,对于单元格格式不受影响
如果想让数据出现在更下面的行,可以通过 sheet.setStartRow() 方法指定一个靠下的行号。

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