csv 导出工具

一般大数据量导出 都会选择 csv 格式，就是存文本格式，相比excel 轻量级，同样数据量 csv 文件更小。

工具类，分页导出

/**
 * Author:   lyc
 * Date:     2024/07/05 16:27
 */
@Slf4j
public class CsvUtils {

    /**
     * 大数量导出
     *
     * @param fileName 生成文件地址
     * @param clazz    类
     * @param pages    总页数
     * @param function 获取数据函数
     * @return
     */
    public static String exportCsv(String fileName, Class clazz, long pages, Function<Integer, List<?>> function) {
        //指定路径和编码
        CsvWriter writer = CsvUtil.getWriter(fileName, CharsetUtil.CHARSET_UTF_8);
        Field[] fields = ReflectUtil.getFields(clazz);
        String[] headerArray = new String[fields.length];
        for (int i = 0; i < fields.length; i++) {
            Field field = fields[i];
            headerArray[i] = Optional.ofNullable(field.getAnnotation(Alias.class))
                    .map(alias -> alias.value())
                    .orElse(field.getName()
                    );
        }
        writer.write(headerArray);
        //按行写出
        for (int i = 1; i <= pages; i++) {
            List list = function.apply(i);
            writeStringArray(list, clazz, writer);
        }
        return fileName;
    }


    /**
     * 字符串数组 写入
     *
     * @param list
     * @return
     */
    private static void writeStringArray(List list, Class clazz, CsvWriter writer) {
        for (int i = 0; i < list.size(); i++) {
            Field[] fields = ReflectUtil.getFields(clazz);
            Object o = list.get(i);
            String[] array = new String[fields.length];
            for (int j = 0; j < fields.length; j++) {
                Field field = fields[j];
                Object fieldValue = ReflectUtil.getFieldValue(o, field);
                array[j] = Optional.ofNullable(fieldValue)
                        .map(value -> formatStr(value))
                        .orElse("");
            }
            writer.write(array);
        }

    }

    /**
     * 格式化数据
     * @param value
     * @return
     */
    private static String formatStr(Object value){
        if(null == value){
            return "";
        }
        if(value instanceof LocalDateTime){
            LocalDateTime dateTime = (LocalDateTime) value;
            return DateUtils.getDateTimeStr(dateTime);
        }
        if(value instanceof LocalDate){
            LocalDate localDate = (LocalDate) value;
            return DateUtils.getDateStr(localDate);
        }
        return String.valueOf(value);
    }
}

使用 类上加注解

 @Alias("活动名称")
    private String name;

String fileName = "e:/testWrite00101.csv";
Integer size = 10;
CsvUtils.exportCsv(fileName, AdminSpecsActivityVO.class,3,(j) -> {
    AdminSpecsActivityQuery adminSpecsActivityQuery = new AdminSpecsActivityQuery();
    adminSpecsActivityQuery.setPageNum(j);
    adminSpecsActivityQuery.setPageSize(size);
    PageVO pageVO = adminSpecsActivityService.page(adminSpecsActivityQuery);
    return pageVO.getList();
});

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