FastExcel: High-Performance Java Excel Library Surpassing EasyExcel

01 Introduction

FastExcel is an upgraded framework released by the original EasyExcel author after Alibaba announced the discontinuation of EasyExcel maintenance. It inherits all advantages of EasyExcel while delivering significant performance and functional improvements.

02 FastExcel Features

High-performance read/write: Optimized for efficient handling of large-scale Excel data with significantly reduced memory footprint.

Simple and intuitive API: Enables quick integration for both simple and complex Excel operations.

Streaming operations: Supports streaming reads to minimize one-time data loading, ideal for hundreds of thousands or millions of rows.

Full compatibility: Fully compatible with all EasyExcel features, allowing seamless migration.

Continuous updates: Ongoing bug fixes, performance optimizations, and new feature additions.

03 FastExcel Usage Guide

Create Entity Class and Listener

Entity Class

Define an entity class where each field maps to an Excel column using the @ExcelProperty annotation.

import cn.idev.excel.annotation.ExcelProperty;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

@Setter
@Getter
@ToString
public class User {
    @ExcelProperty("编号")
    private Integer id;
    @ExcelProperty("名字")
    private String name;
    @ExcelProperty("年龄")
    private Integer age;
}

Event Listener

FastExcel uses event listeners for row-by-row reading, crucial for large files to avoid memory overflow. The listener collects rows and provides a callback after all data is read.

import cn.idev.excel.context.AnalysisContext;
import cn.idev.excel.event.AnalysisEventListener;
import java.util.ArrayList;
import java.util.List;

public class BaseExcelListener<T> extends AnalysisEventListener<T> {
    private List<T> dataList = new ArrayList<>();

    @Override
    public void invoke(T t, AnalysisContext analysisContext) {
        dataList.add(t);
    }

    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {
        System.out.println("读取完成，共读取了 " + dataList.size() + " 条数据");
    }

    public List<T> getDataList() {
        return dataList;
    }
}

Implement Write and Read

Excel Write

Example of writing data to an Excel file via a Spring MVC endpoint. The response is configured for .xlsx download, and FastExcel.write streams the data.

// Excel写入功能
@GetMapping("/download")
public void download(HttpServletResponse response) throws IOException {
    response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
    response.setCharacterEncoding("utf-8");
    String fileName = URLEncoder.encode("test", "UTF-8");
    response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");
    // 写入数据
    FastExcel.write(response.getOutputStream(), User.class)
    .sheet("模板")
    .doWrite(buildData());
}

// 创建测试数据
private List<User> buildData() {
    User user1 = new User();
    user1.setId(1);
    user1.setName("张三");
    user1.setAge(18);
    User user2 = new User();
    user2.setId(2);
    user2.setName("李四");
    user2.setAge(19);
    return List.of(user1, user2);
}

Excel Read

Example of reading an uploaded Excel file using FastExcel.read with the previously defined listener.

// Excel读取功能
@PostMapping("/upload")
public ResponseEntity<String> upload(@RequestParam("file") MultipartFile file) {
    if (file.isEmpty()) {
        return ResponseEntity.badRequest().body("请选择一个文件上传！");
    }
    try {
        BaseExcelListener<User> baseExcelListener = new BaseExcelListener<>();
        FastExcel.read(file.getInputStream(), User.class, baseExcelListener)
        .sheet()
        .doRead();
        List<User> dataList = baseExcelListener.getDataList();
        System.out.println(dataList);
        return ResponseEntity.ok("文件上传并处理成功！");
    } catch (IOException e) {
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("文件处理失败！");
    }
}

Excel to PDF Conversion

FastExcel supports converting Excel files to PDF, relying on Apache POI and itext-pdf. Note that itext-pdf license compliance must be ensured.

FastExcel.convertToPdf(
    new File("excelFile"),
    new File("pdfFile"),
    null,
    null
);

04 Summary

FastExcel is an efficient, easy-to-use Excel processing tool that not only inherits all EasyExcel strengths but also enhances performance and functionality. The examples demonstrate how FastExcel simplifies read/write operations and leverages event listeners for streaming processing to manage memory effectively. It provides strong support for enterprise data import/export and personal projects alike.

05 FastExcel vs EasyExcel Differences

Performance improvement: FastExcel outperforms EasyExcel in both speed and stability.

API consistency: APIs are identical, enabling zero-code migration.

New features: Version 1.0.0 adds reading specified row ranges and Excel-to-PDF conversion.

06 Conclusion

FastExcel is a lightweight yet powerful Java library designed for high-performance, low-memory Excel file processing. For projects handling large-scale Excel data, FastExcel is a compelling choice. Its streaming processing and flexible API make it an ideal tool for Excel file manipulation.