1.poi介绍

pache POI [1]  是创建和维护操作各种符合Office Open XML（OOXML）标准和微软的OLE 2复合文档格式（OLE2）的Java API。用它可以使用Java读取和创建,修改MS Excel文件.而且,还可以使用Java读取和创建MS Word和MSPowerPoint文件。Apache POI 提供Java操作Excel解决方案（适用于Excel97-2008）

2.导入依赖

03版本xml结尾的只能有65535行，07版以xlsx结尾，没有限制

  org.apache.poipoi3.9org.apache.poipoi-ooxml3.9joda-timejoda-time2.10.1junitjunit4.12

 3.写入Excel

03版本用的是HSSF,07版本用的是XSSF

3-1.03测试代码 xls

package com.example.list.controller;import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.joda.time.DateTime;
import org.junit.Test;import java.io.FileOutputStream;//写测试
public class ExcelWriteTest {String PATH = "E:\\java\\list\\";@Testpublic void test01() throws Exception {//1.创建工作簿Workbook workbook = new HSSFWorkbook();//2.创建一个工作表Sheet sheet = workbook.createSheet("统计表");//第一行//3.创建一个行Row row1 = sheet.createRow(0);//4.创建一个单元格//(1,1)Cell cell11 = row1.createCell(0);cell11.setCellValue("今日新增观众");//4.创建一个单元格//(1,2)Cell cell12 = row1.createCell(1);cell12.setCellValue(6666);//第二行（2,1）Row row2 = sheet.createRow(1);Cell cell21 = row2.createCell(0);cell21.setCellValue("统计时间");//(2,2)Cell cell22 = row2.createCell(1);String time = new DateTime().toString("yyyy-MM-dd HH:mm:ss");cell22.setCellValue(time);//生成一张表FileOutputStream fileOutputStream = new FileOutputStream(PATH + "统计表03.xls");workbook.write(fileOutputStream);fileOutputStream.close();System.out.println("生成完毕");}
}

3-2.07版本xlsx

package com.example.list.controller;import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.joda.time.DateTime;
import org.junit.Test;import java.io.FileOutputStream;//写测试
public class ExcelWriteTest {String PATH = "E:\\java\\list\\";@Testpublic void test01() throws Exception {//1.创建工作簿Workbook workbook = new XSSFWorkbook();//2.创建一个工作表Sheet sheet = workbook.createSheet("统计表");//第一行//3.创建一个行Row row1 = sheet.createRow(0);//4.创建一个单元格//(1,1)Cell cell11 = row1.createCell(0);cell11.setCellValue("今日新增观众");//4.创建一个单元格//(1,2)Cell cell12 = row1.createCell(1);cell12.setCellValue(6666);//第二行（2,1）Row row2 = sheet.createRow(1);Cell cell21 = row2.createCell(0);cell21.setCellValue("统计时间");//(2,2)Cell cell22 = row2.createCell(1);String time = new DateTime().toString("yyyy-MM-dd HH:mm:ss");cell22.setCellValue(time);//生成一张表FileOutputStream fileOutputStream = new FileOutputStream(PATH + "统计表07.xlsx");workbook.write(fileOutputStream);fileOutputStream.close();System.out.println("生成完毕");}
}

 4.大数据导入

4-1 03版本

03版本耗时2.83秒（每个人电脑性能不一样） 03版本只能处理65536行，过程中写入缓存，不操作磁盘，写入速度快

package com.example.list.controller;import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;import org.junit.Test;
import java.io.FileOutputStream;//写测试
public class ExcelWriteTest {String PATH = "E:\\java\\list\\";@Testpublic void testBigData() throws Exception {//开始时间long begin = System.currentTimeMillis();//创建一个薄HSSFWorkbook workbook = new HSSFWorkbook();//创建一个表Sheet sheet = workbook.createSheet();//写入数据//行for (int rowNum = 0; rowNum < 65536; rowNum++) {Row row = sheet.createRow(rowNum);//列for (int cellNum = 0; cellNum < 10; cellNum++) {Cell cell = row.createCell(cellNum);cell.setCellValue(cellNum);}}System.out.println("完成");FileOutputStream fileOutputStream = new FileOutputStream(PATH + "大数据03.xls");workbook.write(fileOutputStream);fileOutputStream.close();long end = System.currentTimeMillis();System.out.println((double)( end-begin)/1000);}
}

4-2 07版本

07版本速度慢，写入耗内存，也会内存溢出,我电脑是 4.28秒，处理65536行。

package com.example.list.controller;import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.junit.Test;import java.io.FileOutputStream;//写测试
public class ExcelWriteTest {String PATH = "E:\\java\\list\\";@Testpublic void testBigData() throws Exception {//开始时间long begin = System.currentTimeMillis();//创建一个薄Workbook workbook = new XSSFWorkbook();//创建一个表Sheet sheet = workbook.createSheet();//写入数据//行for (int rowNum = 0; rowNum < 65536; rowNum++) {Row row = sheet.createRow(rowNum);//列for (int cellNum = 0; cellNum < 10; cellNum++) {Cell cell = row.createCell(cellNum);cell.setCellValue(cellNum);}}System.out.println("完成");FileOutputStream fileOutputStream = new FileOutputStream(PATH + "大数据07.xlsx");workbook.write(fileOutputStream);fileOutputStream.close();long end = System.currentTimeMillis();System.out.println((double) (end - begin) / 1000);}
}

对于写入慢的问题，大文件可以写SCSSF,在写入过程中会生成临时文件，内存只有100条，可以自己修改 

package com.example.list.controller;import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import org.junit.Test;import java.io.FileOutputStream;//写测试
public class ExcelWriteTest {String PATH = "E:\\java\\list\\";@Testpublic void testBigData() throws Exception {//开始时间long begin = System.currentTimeMillis();//创建一个薄Workbook workbook = new SXSSFWorkbook();//创建一个表Sheet sheet = workbook.createSheet();//写入数据//行for (int rowNum = 0; rowNum < 1000000; rowNum++) {Row row = sheet.createRow(rowNum);//列for (int cellNum = 0; cellNum < 10; cellNum++) {Cell cell = row.createCell(cellNum);cell.setCellValue(cellNum);}}System.out.println("完成");FileOutputStream fileOutputStream = new FileOutputStream(PATH + "大数据07.xlsx");workbook.write(fileOutputStream);fileOutputStream.close();//清楚临时文件((SXSSFWorkbook)workbook).dispose();long end = System.currentTimeMillis();System.out.println((double) (end - begin) / 1000);}
}

5.excel读

5-1 03版本

package com.example.list.controller;import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.junit.Test;import java.io.FileInputStream;public class ExcelReadTest {public static final String PATH = "E:\\java\\list\\";@Testpublic void testRead03() throws Exception {//获取文件流FileInputStream inputStream = new FileInputStream(PATH+"统计表03.xls");//创建一个工作薄，HSSFWorkbook workbook = new HSSFWorkbook(inputStream);//得到表Sheet sheet = workbook.getSheetAt(0);//得到行Row row = sheet.getRow(0);//得到列Cell cell = row.getCell(0);System.out.println(cell.getStringCellValue());inputStream.close();}
}

5-2 07版本

package com.example.list.controller;import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.junit.Test;import java.io.FileInputStream;public class ExcelReadTest {public static final String PATH = "E:\\java\\list\\";@Testpublic void testRead07() throws Exception {//获取文件流FileInputStream inputStream = new FileInputStream(PATH+"统计表07.xlsx");//创建一个工作薄，Workbook workbook = new XSSFWorkbook(inputStream);//得到表Sheet sheet = workbook.getSheetAt(0);//得到行Row row = sheet.getRow(0);//得到列Cell cell = row.getCell(0);System.out.println(cell.getStringCellValue());inputStream.close();}
}