导入导出笔记-easyExcel初探(表格导入和模板化导出)

前言

本文使用的EasyExcel Alibaba和EasyPoi Apache技术栈分析

• EasyExcel Dependency
  

• EasyPoi Dependency
  

---

1、需求一：表格化需求导入导出(难度星级：☆)

导入导出模板

实体对象

这里我们用到了一个注解com.alibaba.excel.annotation.ExcelProperty

@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface ExcelProperty {

    /**
     * The name of the sheet header.
     *
     * <p>
     * write: It automatically merges when you have more than one head
     * <p>
     * read: When you have multiple heads, take the first one
     *
     * @return The name of the sheet header
     */
    String[] value() default {""};

    /**
     * Index of column
     *
     * Read or write it on the index of column,If it's equal to -1, it's sorted by Java class.
     *
     * priority: index &gt; order &gt; default sort
     *
     * @return Index of column
     */
    int index() default -1;

    /**
     * Defines the sort order for an column.
     *
     * priority: index &gt; order &gt; default sort
     *
     * @return Order of column
     */
    int order() default Integer.MAX_VALUE;

    /**
     * Force the current field to use this converter.
     *
     * @return Converter
     */
    Class<? extends Converter> converter() default AutoConverter.class;

    /**
     *
     * default @see com.alibaba.excel.util.TypeUtil if default is not meet you can set format
     *
     * @return Format string
     * @deprecated please use {@link com.alibaba.excel.annotation.format.DateTimeFormat}
     */
    @Deprecated
    String format() default "";
}

此处使用到的value注解，其余属性不扩展，有想了解的东西可以关注公众号“技术小邱”了解
注意，导出时此处value值要和excel值完全匹配，包括空格

• 导入：解析excel
  EasyExcel.read(file.getInputStream()).head(Student.class).autoCloseStream(true) .autoTrim(true).sheet().doReadSync()
• 导出：生成excel

WriteSheet studentSheet = EasyExcel.writerSheet("学生信息").head(ClaimReportListExportDTO.class).build();
excelWriter.write(studentList, studentSheet);

2、模板化导出(难度：☆☆☆)

模板样式

首先我们需要更换模板，填充代入代码

第一步：获取模板输入流信息(读取模板信息)
InputStream in = this.getClass().getResourceAsStream(fileName)
第二步：转换成输出流(写入目标文件)

ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len;
while ((len = in.read(buffer)) > -1) {
   outputStream.write(buffer, 0, len);
}
outputStream.flush();
in.close();

第三步：目标写入

WriteSheet writeSheet = EasyExcel.writerSheet().build();
FillConfig fillConfig = FillConfig.builder().forceNewRow(Boolean.TRUE).build();
excelWriter.fill(studentInfoList, fillConfig, writeSheet);
ExcelWriter excelWriter = EasyExcel.write(outputStream).withTemplate(byteArrayInputStream)
                    .autoCloseStream(Boolean.TRUE).build();
excelWriter.finish();

这样就完成对应的导出了

以上均可以通过EasyExcel实现,EasyPoi目前运用比较多的是列表动态扩展，后面的博客将会讲到
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