Implementing a FIFO Export Queue for Large Data Exports in Java

The business requirement is to handle growing database export volumes without degrading server performance; a fixed‑size FIFO queue is introduced to serialize export tasks, limiting concurrent MySQL I/O and file I/O.

Three main components are defined: ExportQueue for managing a bounded user queue, User information representing the export requester, and an Export class that performs the actual data export.

package com.example.system.config; import com.example.system.api.domain.ExportUser; import lombok.extern.slf4j.Slf4j; import org.springframework.stereotype.Component; import java.util.LinkedList; @Slf4j @Component public class ExportQueue { private final int MAX_CAPACITY = 10; // 队列最大容量 private LinkedList queue; // 用户队列 public ExportQueue(LinkedList queue) { this.queue = new LinkedList<>(); } /** * 排队队列添加 * @param sysUser */ public synchronized LinkedList add(ExportUser sysUser) { while (queue.size() >= MAX_CAPACITY) { try { log.info("当前排队人已满，请等待"); wait(); } catch (InterruptedException e) { e.getMessage(); } } queue.add(sysUser); log.info("目前导出队列排队人数：" + queue.size()); notifyAll(); return queue; } /** * 获取排队队列下一个人 */ public synchronized ExportUser getNextSysUser() { while (queue.isEmpty()) { try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } } ExportUser sysUser = queue.remove(); notifyAll(); // 唤醒 return sysUser; } }

The AbstractExport class defines a generic export framework using EasyExcel, handling pagination, file naming, and error handling while leaving data‑specific methods abstract.

package com.example.system.config; import cn.hutool.core.bean.BeanUtil; import cn.hutool.core.util.PageUtil; import com.alibaba.excel.EasyExcel; import com.alibaba.excel.ExcelWriter; import com.alibaba.excel.write.metadata.WriteSheet; import com.example.system.api.domain.ExportUser; import lombok.extern.slf4j.Slf4j; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.net.URLEncoder; import java.util.List; @Slf4j public abstract class AbstractExport { public abstract void export(ExportUser sysUser) throws InterruptedException; /** * 导出 */ public void export(HttpServletResponse response, int pageSize, T t, Class k, String fileName) throws Exception { ExcelWriter writer = null; try { writer = getExcelWriter(response, fileName); int total = this.countExport(t); // 查询导出总条数 int loopCount = PageUtil.totalPage(total, pageSize); BeanUtil.setProperty(t, "pageSize", pageSize); for (int i = 0; i < loopCount; i++) { BeanUtil.setProperty(t, "pageNum", PageUtil.getStart(i + 1, pageSize)); List kList = this.getExportDetail(t); WriteSheet writeSheet = EasyExcel.writerSheet(fileName).head(k).build(); writer.write(kList, writeSheet); } } catch (Exception e) { String msg = "导出" + fileName + "异常"; log.error(msg, e); throw new Exception(msg + e); } finally { if (writer != null) { writer.finish(); } } } public ExcelWriter getExcelWriter(HttpServletResponse response, String fileName) throws IOException { response.setContentType("application/vnd.ms-excel"); response.setCharacterEncoding("utf-8"); String fileNameUtf = URLEncoder.encode(fileName, "UTF-8").replaceAll("\\+", "%20"); response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileNameUtf + ".xlsx"); return EasyExcel.write(response.getOutputStream()).build(); } public abstract void complexFillWithTable(T t, String fileName, HttpServletResponse response); public abstract int countExport(T t); public abstract List getExportDetail(T t); }

The ExportImpl class extends AbstractExport , injects the ExportQueue , and implements the export logic, including simulated processing delay and queue management.

package com.example.system.service.impl; import com.alibaba.excel.ExcelWriter; import com.example.system.api.domain.ExportUser; import com.example.system.config.AbstractExport; import com.example.system.config.ExportQueue; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.util.LinkedList; import java.util.List; @Service @Slf4j public class ExportImpl extends AbstractExport { @Autowired private ExportQueue exportQueue; @Override public void export(ExportUser sysUser) throws InterruptedException { log.info("导出文件方法执行～～～～～～～～～"); LinkedList queue = exportQueue.add(sysUser); log.info("导出队列：" + queue); Thread.sleep(20000); // 模拟导出处理时间 ExportUser nextSysUser = exportQueue.getNextSysUser(); log.info("移除后获取下一个排队的用户: " + nextSysUser.getUserName()); } @Override public void export(HttpServletResponse response, int pageSize, Object o, Class k, String fileName) throws Exception { super.export(response, pageSize, o, k, fileName); } @Override public ExcelWriter getExcelWriter(HttpServletResponse response, String fileName) throws IOException { return super.getExcelWriter(response, fileName); } @Override public void complexFillWithTable(Object o, String fileName, HttpServletResponse response) { // not implemented } @Override public int countExport(Object o) { return 0; } @Override public List getExportDetail(Object o) { return null; } }

A simple ExportController demonstrates how multiple threads can invoke the export service, each creating an ExportUser and adding it to the queue.

package com.example.system.controller; import com.example.system.api.domain.ExportUser; import com.example.system.service.impl.ExportImpl; import lombok.SneakyThrows; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController @RequestMapping("/export") @Slf4j public class ExportController { @Autowired private ExportImpl export; @PostMapping("/exportFile") public void exportFile() { new Thread(new Runnable() { @SneakyThrows @Override public void run() { Thread thread1 = Thread.currentThread(); ExportUser sysUser = new ExportUser(); sysUser.setUserName(thread1.getName()); export.export(sysUser); } }).start(); } }

Test results confirm that the queue enforces a maximum of ten concurrent export requests; when the limit is reached, additional requests wait until a slot becomes free, demonstrating proper FIFO behavior.

The article concludes with remarks about unfinished features (file table design, OSS upload, download, high‑concurrency considerations) and suggests that a Redis‑based queue could be an alternative implementation.