POI之SXSSFWorkbook大量数据导出至excel
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一:简介
SXSSFWorkbook是用来生成海量excel数据文件,主要原理是借助临时存储空间生成excel,
SXSSFWorkbook专门处理大数据,对于大型excel的创建且不会内存溢出的,就只有SXSSFWorkbook了。
它的原理很简单,用硬盘空间换内存(就像hashmap用空间换时间一样)。 SXSSFWorkbook是streaming
版本的XSSFWorkbook,它只会保存最新的excel rows在内存里供查看,在此之前的excel rows都会被写入到
硬盘里(Windows电脑的话,是写入到C盘根目录下的temp文件夹)。被写入到硬盘里的rows是不可见的/不
可访问的。只有还保存在内存里的才可以被访问到。
注:HSSFWorkbook和XSSFWorkbook的Excel Sheet导出条数上限(<=2003版)是65535行、256列,(>=2007版)
是1048576行,16384列,如果数据量超过了此上限,那么可以使用SXSSFWorkbook来导出。实际上上万条数据,
甚至上千条数据就可以考虑使用SXSSFWorkbook了。
注意:首先需要引入依赖:注意:4.0.0版本的JDK需要1.8以上,如果JDK是1.7的,那么就使用3.9版本的依赖
<!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml-schemas -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml-schemas</artifactId>
<version>4.0.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>4.0.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>4.0.0</version>
</dependency>
二:实例一,我们使用SXSSFWorkbook向Excel中写入50万条数据,只需要 34秒左右,内存占用率最多在700M左右,CPU使用率在25%左右
代码如下:
package com.test.POI;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.xssf.streaming.SXSSFRow;
import org.apache.poi.xssf.streaming.SXSSFSheet;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class SXSSFWORKBookUtils
@SuppressWarnings("resource")
public static void main(String[] args) throws FileNotFoundException, InvalidFormatException
long startTime = System.currentTimeMillis();
String filePath = "E:\\\\txt\\\\111.xlsx";
SXSSFWorkbook sxssfWorkbook = null;
BufferedOutputStream outputStream = null;
try
//这样表示SXSSFWorkbook只会保留100条数据在内存中,其它的数据都会写到磁盘里,这样的话占用的内存就会很少
sxssfWorkbook = new SXSSFWorkbook(getXSSFWorkbook(filePath),100);
//获取第一个Sheet页
SXSSFSheet sheet = sxssfWorkbook.getSheetAt(0);
for (int i = 0; i < 50; i++)
for (int z = 0; z < 10000; z++)
SXSSFRow row = sheet.createRow(i*10000+z);
for (int j = 0; j < 10; j++)
row.createCell(j).setCellValue("你好:"+j);
outputStream = new BufferedOutputStream(new FileOutputStream(filePath));
sxssfWorkbook.write(outputStream);
outputStream.flush();
sxssfWorkbook.dispose();// 释放workbook所占用的所有windows资源
catch (IOException e)
e.printStackTrace();
finally
if(outputStream!=null)
try
outputStream.close();
catch (IOException e)
e.printStackTrace();
long endTime = System.currentTimeMillis();
System.out.println(endTime-startTime);
/**
* 先创建一个XSSFWorkbook对象
* @param filePath
* @return
*/
public static XSSFWorkbook getXSSFWorkbook(String filePath)
XSSFWorkbook workbook = null;
BufferedOutputStream outputStream = null;
try
File fileXlsxPath = new File(filePath);
outputStream = new BufferedOutputStream(new FileOutputStream(fileXlsxPath));
workbook = new XSSFWorkbook();
workbook.createSheet("测试Sheet");
workbook.write(outputStream);
catch (Exception e)
e.printStackTrace();
finally
if(outputStream!=null)
try
outputStream.close();
catch (IOException e)
e.printStackTrace();
return workbook;
效果:
三:我们使用XSSFWorkbook常规的方法分批向excel中写入50万条数据,内 存占用率最多在 2.1个G左右(占用了很大的内存),CPU使用率在90% 左右 ,最后内存 溢出了
代码如下:
package com.test;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class POIController
/**
* 这种方式效率比较低并且特别占用内存,数据量越大越明显
* @param args
* @throws FileNotFoundException
* @throws InvalidFormatException
*/
public static void main(String[] args) throws FileNotFoundException, InvalidFormatException
long startTime = System.currentTimeMillis();
BufferedOutputStream outPutStream = null;
XSSFWorkbook workbook = null;
FileInputStream inputStream = null;
String filePath = "E:\\\\txt\\\\666.xlsx";
try
workbook = getWorkBook(filePath);
XSSFSheet sheet = workbook.getSheetAt(0);
for (int i = 0; i < 50; i++)
for (int z = 0; z < 10000; z++)
XSSFRow row = sheet.createRow(i*10000+z);
for (int j = 0; j < 10; j++)
row.createCell(j).setCellValue("你好:"+j);
//每次要获取新的文件流对象,避免将之前写入的数据覆盖掉
outPutStream = new BufferedOutputStream(new FileOutputStream(filePath));
workbook.write(outPutStream);
catch (IOException e)
e.printStackTrace();
finally
if(outPutStream!=null)
try
outPutStream.close();
catch (IOException e)
e.printStackTrace();
if(inputStream!=null)
try
inputStream.close();
catch (IOException e)
e.printStackTrace();
if(workbook!=null)
try
workbook.close();
catch (IOException e)
e.printStackTrace();
long endTime = System.currentTimeMillis();
System.out.println(endTime-startTime);
/**
* 先创建一个XSSFWorkbook对象
* @param filePath
* @return
*/
public static XSSFWorkbook getWorkBook(String filePath)
XSSFWorkbook workbook = null;
try
File fileXlsxPath = new File(filePath);
BufferedOutputStream outPutStream = new BufferedOutputStream(new FileOutputStream(fileXlsxPath));
workbook = new XSSFWorkbook();
workbook.createSheet("测试");
workbook.write(outPutStream);
catch (Exception e)
e.printStackTrace();
return workbook;
效果:
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