EasyExcel注解实现导出保留2位小数

Lcry

发布于 2023-03-17 08:28:16

2.8K0

发布于 2023-03-17 08:28:16

文章被收录于专栏：Lcry个人博客Lcry个人博客

前言

最近项目上做个需求，需要将成绩导出成excel多个sheet中，针对平均分、百分比这类的值数据库存的是浮点数，所以在展示的时候我们一般保留小数后2位小数。

我们常见的处理办法：

通过计算之后直接在数据库中保存保留2位小数的值；
通过写SQL的时候查询的时候直接处理，比如使用ROUND(X,D) 函数、FORMAT（X,D）等函数；
通过代码实现进行保留小数处理；
项目使用的EasyExcel通过打注解的方式，导出自动保留2位小数。

综上，为了保证最高的兼容性和耦合性，直接采用注解导出的时候格式化。

EasyExcel介绍

EasyExcel是一个基于Java的、快速、简洁、解决大文件内存溢出的Excel处理工具。他能让你在不用考虑性能、内存的等因素的情况下，快速完成Excel的读、写等功能。

官方网站：https://easyexcel.opensource.alibaba.com/

github地址：https://github.com/alibaba/easyexcel

gitee地址：https://gitee.com/easyexcel/easyexcel

使用

导出模型demo：

   //省略......
    @ExcelProperty(value = "语文", order = 1)
    @ContentStyle(dataFormat = 2)
    private Double yw;
    @ExcelProperty(value = "数学", order = 2)
    @ContentStyle(dataFormat = 2)
    private Double sx;

@ContentStyle注解对应的dataFormat=2 ，这个注解的dataFormat就是设置格式的，他的值是BuiltinFormats类中_formats数组中对应格式的下标，源码如下：

package org.apache.poi.ss.usermodel;

/**
 * Utility to identify built-in formats.  The following is a list of the formats as
 * returned by this class.<p>
 *<p>
 *       0, "General"<br>
 *       1, "0"<br>
 *       2, "0.00"<br>
 *       3, "#,##0"<br>
 *       4, "#,##0.00"<br>
 *       5, "$#,##0_);($#,##0)"<br>
 *       6, "$#,##0_);[Red]($#,##0)"<br>
 *       7, "$#,##0.00);($#,##0.00)"<br>
 *       8, "$#,##0.00_);[Red]($#,##0.00)"<br>
 *       9, "0%"<br>
 *       0xa, "0.00%"<br>
 *       0xb, "0.00E+00"<br>
 *       0xc, "# ?/?"<br>
 *       0xd, "# ??/??"<br>
 *       0xe, "m/d/yy"<br>
 *       0xf, "d-mmm-yy"<br>
 *       0x10, "d-mmm"<br>
 *       0x11, "mmm-yy"<br>
 *       0x12, "h:mm AM/PM"<br>
 *       0x13, "h:mm:ss AM/PM"<br>
 *       0x14, "h:mm"<br>
 *       0x15, "h:mm:ss"<br>
 *       0x16, "m/d/yy h:mm"<br>
 *<p>
 *       // 0x17 - 0x24 reserved for international and undocumented
 *       0x25, "#,##0_);(#,##0)"<br>
 *       0x26, "#,##0_);[Red](#,##0)"<br>
 *       0x27, "#,##0.00_);(#,##0.00)"<br>
 *       0x28, "#,##0.00_);[Red](#,##0.00)"<br>
 *       0x29, "_(* #,##0_);_(* (#,##0);_(* \"-\"_);_(@_)"<br>
 *       0x2a, "_($* #,##0_);_($* (#,##0);_($* \"-\"_);_(@_)"<br>
 *       0x2b, "_(* #,##0.00_);_(* (#,##0.00);_(* \"-\"??_);_(@_)"<br>
 *       0x2c, "_($* #,##0.00_);_($* (#,##0.00);_($* \"-\"??_);_(@_)"<br>
 *       0x2d, "mm:ss"<br>
 *       0x2e, "[h]:mm:ss"<br>
 *       0x2f, "mm:ss.0"<br>
 *       0x30, "##0.0E+0"<br>
 *       0x31, "@" - This is text format.<br>
 *       0x31  "text" - Alias for "@"<br>
 * <p>
 */
public final class BuiltinFormats {
    /**
     * The first user-defined number format starts at 164.
     */
    public static final int FIRST_USER_DEFINED_FORMAT_INDEX = 164;

    private final static String[] _formats = {
        "General",
        "0",
        "0.00",
        "#,##0",
        "#,##0.00",
        "\"$\"#,##0_);(\"$\"#,##0)",
        "\"$\"#,##0_);[Red](\"$\"#,##0)",
        "\"$\"#,##0.00_);(\"$\"#,##0.00)",
        "\"$\"#,##0.00_);[Red](\"$\"#,##0.00)",
        "0%",
        "0.00%",
        "0.00E+00",
        "# ?/?",
        "# ??/??",
        "m/d/yy",
        "d-mmm-yy",
        "d-mmm",
        "mmm-yy",
        "h:mm AM/PM",
        "h:mm:ss AM/PM",
        "h:mm",
        "h:mm:ss",
        "m/d/yy h:mm",

        // 0x17 - 0x24 reserved for international and undocumented
        // TODO - one junit relies on these values which seems incorrect
        "reserved-0x17",
        "reserved-0x18",
        "reserved-0x19",
        "reserved-0x1A",
        "reserved-0x1B",
        "reserved-0x1C",
        "reserved-0x1D",
        "reserved-0x1E",
        "reserved-0x1F",
        "reserved-0x20",
        "reserved-0x21",
        "reserved-0x22",
        "reserved-0x23",
        "reserved-0x24",
        
        "#,##0_);(#,##0)",
        "#,##0_);[Red](#,##0)",
        "#,##0.00_);(#,##0.00)",
        "#,##0.00_);[Red](#,##0.00)",
        "_(* #,##0_);_(* (#,##0);_(* \"-\"_);_(@_)",
        "_(\"$\"* #,##0_);_(\"$\"* (#,##0);_(\"$\"* \"-\"_);_(@_)",
        "_(* #,##0.00_);_(* (#,##0.00);_(* \"-\"??_);_(@_)",
        "_(\"$\"* #,##0.00_);_(\"$\"* (#,##0.00);_(\"$\"* \"-\"??_);_(@_)",
        "mm:ss",
        "[h]:mm:ss",
        "mm:ss.0",
        "##0.0E+0",
        "@"
    };

    /**
     * @return array of built-in data formats
     */
    public static String[] getAll() {
        return _formats.clone();
    }

    /**
     * Get the format string that matches the given format index
     *
     * @param index of a built in format
     * @return string represented at index of format or <code>null</code> if there is not a built-in format at that index
     */
    public static String getBuiltinFormat(int index) {
        if (index < 0 || index >=_formats.length) {
            return null;
        }
        return _formats[index];
    }

    /**
     * Get the format index that matches the given format string.<br>
     * Automatically converts "text" to excel's format string to represent text.
     * 
     * @param pFmt string matching a built-in format
     * @return index of format or -1 if undefined.
     */
    public static int getBuiltinFormat(String pFmt) {
        String fmt = "TEXT".equalsIgnoreCase(pFmt) ? "@" : pFmt;

        int i = -1;
        for (String f : _formats) {
            i++;
            if (f.equals(fmt)) {
                return i; 
            }
        }
        
        return -1;
    }
}