Boost Java Excel Performance with FastExcel: Features, Usage, and Comparison

Introduction

FastExcel is an upgraded framework released by the original EasyExcel author after Alibaba stopped maintaining EasyExcel. It inherits all advantages and significantly improves performance and functionality.

Features of FastExcel

High-performance read/write : optimized for large‑scale Excel data with low memory usage.

Simple to use : concise API for quick integration.

Streaming operations : supports streaming reads, suitable for hundreds of thousands to millions of rows.

Full compatibility : compatible with all EasyExcel features.

Continuous updates : ongoing bug fixes and enhancements.

Detailed Usage

Creating Entity Class and Listener

Entity Class

Define an entity class where each field maps to an Excel column, using the

@ExcelProperty

annotation to specify column names.

<code>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;
}
</code>

Event Listener

FastExcel uses an event listener for row‑by‑row reading, preventing memory overflow.

<code>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;
    }
}
</code>

Read and Write Operations

Excel Write

Example of writing data to an Excel file.

<code>// Excel write
@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");
    // Write data
    FastExcel.write(response.getOutputStream(), User.class)
        .sheet("模板")
        .doWrite(buildData());
}

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);
}
</code>

Excel Read

Example of reading an Excel file using the previously defined listener.

<code>// Excel read
@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！");
    }
}
</code>

Excel to PDF Conversion

FastExcel can convert Excel files to PDF using Apache POI and iText PDF (license compliance required).

<code>FastExcel.convertToPdf(new File("excelFile"), new File("pdfFile"), null, null);
</code>

Comparison with EasyExcel

Performance improvement : Faster and more stable.

API consistency : Fully compatible API for seamless migration.

Additional features : Supports reading specific rows and Excel‑to‑PDF conversion.

Conclusion

FastExcel is a lightweight yet powerful Java library designed for high‑performance, low‑memory Excel processing. Its streaming capabilities and flexible API make it an ideal choice for projects that need to handle large Excel datasets efficiently.

Project URL

https://github.com/CodePhiliaX/fastexcel