Java多线程分批导出excel
时间: 2023-07-06 12:40:26 浏览: 74
Java多线程分批导出Excel可以提高导出效率,可以使用线程池和CountDownLatch来实现。以下是一个示例代码片段:
```java
public void exportToExcel(List<List<String>> data, int batchSize, String filePath, int threadCount) throws InterruptedException, ExecutionException, IOException {
Workbook workbook = new XSSFWorkbook();
// 使用线程池和CountDownLatch来实现多线程导出
ExecutorService executorService = Executors.newFixedThreadPool(threadCount);
CountDownLatch countDownLatch = new CountDownLatch(threadCount);
// 计算每个线程需要导出的数据量
int dataSize = data.size();
int batchCount = dataSize % batchSize == 0 ? dataSize / batchSize : dataSize / batchSize + 1;
int batchCountPerThread = batchCount % threadCount == 0 ? batchCount / threadCount : batchCount / threadCount + 1;
// 创建多个导出任务
List<Future<?>> futures = new ArrayList<>();
for (int i = 0; i < threadCount; i++) {
int startIndex = i * batchCountPerThread * batchSize;
int endIndex = Math.min((i + 1) * batchCountPerThread * batchSize, dataSize);
List<List<String>> subData = data.subList(startIndex, endIndex);
ExportTask exportTask = new ExportTask(subData, batchSize, workbook, countDownLatch);
futures.add(executorService.submit(exportTask));
}
// 等待所有任务执行完毕
countDownLatch.await();
// 导出Excel文件
try (OutputStream outputStream = new FileOutputStream(filePath)) {
workbook.write(outputStream);
}
// 关闭线程池
executorService.shutdown();
}
private static class ExportTask implements Runnable {
private List<List<String>> data;
private int batchSize;
private Workbook workbook;
private CountDownLatch countDownLatch;
public ExportTask(List<List<String>> data, int batchSize, Workbook workbook, CountDownLatch countDownLatch) {
this.data = data;
this.batchSize = batchSize;
this.workbook = workbook;
this.countDownLatch = countDownLatch;
}
@Override
public void run() {
int rowIndex = 0;
Sheet sheet = workbook.createSheet();
for (List<String> rowData : data) {
// 如果当前工作表的数据超过指定大小,则新建一个工作表
if (rowIndex % batchSize == 0 && rowIndex > 0) {
sheet = workbook.createSheet();
rowIndex = 0;
}
Row row = sheet.createRow(rowIndex++);
int cellIndex = 0;
for (String cellData : rowData) {
Cell cell = row.createCell(cellIndex++);
cell.setCellValue(cellData);
}
}
countDownLatch.countDown();
}
}
```
在上述代码中,使用了线程池和CountDownLatch来实现多线程导出。首先计算了每个线程需要导出的数据量,然后创建多个导出任务,每个任务负责导出一部分数据到Excel中。在导出过程中,如果当前工作表的数据超过指定大小,则新建一个工作表。所有任务执行完毕后,将Excel文件写入到磁盘中。