小文件写出
03版本的excel：用HSSFWorkbook
public class excelWriteTest {
static String PATH ="D:\\springbootProject\\poi\\src\\main\\java";
@Test
public void testWrite03() throws IOException {
//创建工作本
Workbook workbook=new HSSFWorkbook();
//创建工作表
Sheet sheet = workbook.createSheet("我能快速上手项目");
//创建行(第一行用0表示
Row row1 = sheet.createRow(0);
//创建单元格
Cell cell11 = row1.createCell(0);
cell11.setCellValue("我能快速上手");
//第二行
Row row2=sheet.createRow(1);
Cell cell21 = row2.createCell(0);
cell21.setCellValue("统计时间");
Cell cell22=row2.createCell(1);
String time = new DateTime().toString("yyyy-MM-dd HH:mm:ss");
cell22.setCellValue(time);
//生成一张表（io）
FileOutputStream fileOutputStream = new FileOutputStream(PATH + "pzh学习表.xls");
workbook.write(fileOutputStream);
fileOutputStream.close();
System.out.println("生成完毕");
}
}07版本主要是对象不一样硬XSSF
大数据写出
03版本的Excel的最多只能处理65536行，否则抛出异常
03这个是批量的导入过程写入缓存，不操作磁盘，最后一次写入磁盘，速度快
public class excelWriteTest {
static String PATH ="D:\\springbootProject\\poi\\src\\main\\java";
@Test
public void testWrite03() throws IOException {
//创建工作本
Workbook workbook=new HSSFWorkbook();
//创建工作表
Sheet sheet = workbook.createSheet("我能快速上手项目");
//创建行(第一行用0表示
Row row1 = sheet.createRow(0);
//创建单元格
Cell cell11 = row1.createCell(0);
cell11.setCellValue("我能快速上手");
//第二行
Row row2=sheet.createRow(1);
Cell cell21 = row2.createCell(0);
cell21.setCellValue("统计时间");
Cell cell22=row2.createCell(1);
String time = new DateTime().toString("yyyy-MM-dd HH:mm:ss");
cell22.setCellValue(time);
//生成一张表（io）
FileOutputStream fileOutputStream = new FileOutputStream(PATH + "pzh学习表.xls");
workbook.write(fileOutputStream);
fileOutputStream.close();
System.out.println("生成完毕");
}
@Test
public void testWrite03BigData() throws IOException {
//时间
long begin = System.currentTimeMillis();
//创建本
Workbook workbook = new HSSFWorkbook();
//创建表
Sheet sheet = workbook.createSheet(); //不写用默认名字；
//写入数据
for(int rowNum=0;rowNum<65536;rowNum++){
Row row = sheet.createRow(rowNum);
for(int cellNum=0;cellNum<=10;cellNum++){
Cell cell=row.createCell(cellNum);
cell.setCellValue(cellNum);
}
}
System.out.println("over");
FileOutputStream outputStream = new FileOutputStream(PATH + "testWrite03.xls");
workbook.write(outputStream);
outputStream.close();
long end=System.currentTimeMillis();
System.out.println((double) (end-begin)/1000);
}
}读取导入
注意这个读取的时候，hssfwordbook的构造器要传入流，在cell.get的时候要注意类型（很坑这里）
@Test
public void testRead03() throws IOException {
//获取流
FileInputStream fileInputStream = new FileInputStream(PATH + "javapzh学习表.xls");
Workbook workbook = new HSSFWorkbook(fileInputStream);
//拿到这种表
Sheet sheet = workbook.getSheetAt(0);
Row row = sheet.getRow(0);
Cell cell = row.getCell(0);
System.out.println(cell.getStringCellValue());
fileInputStream.close();
}读取不同类型
//读取不同类型的数据
public class ReadDifferentType {
//excel文件路径
static String path = "C:\\Users\\lenovo\\Desktop\\idea_workspace\\springboot_poi\\";
public static void main(String[] args) throws Exception {
readDifferentType();
}
public static void readDifferentType() throws Exception{
//1.创建流来获得excel表
FileInputStream fileInputStream = new FileInputStream(path + "07版本表.xlsx");
//2.读取excel工作簿
Workbook workbook = new XSSFWorkbook(fileInputStream);
//3.读取第一张表
Sheet sheet = workbook.getSheetAt(0);
//4.读取第一行
Row row_1 = sheet.getRow(0);
//5.输出第一行的内容
if(row_1 != null) {
//获取这行的个数
int cellCount = row_1.getPhysicalNumberOfCells();
for (int i = 0; i < cellCount ; i++){
Cell cell = row_1.getCell(i);
if(cell != null){
//标题都是String,这里不需要判断
int cellType = cell.getCellType();
String cellValue = cell.getStringCellValue();
System.out.println("第1行第"+(i+1)+"列，值为："+cellValue);
}
}
}
System.out.println("============");
//6.获取表中的内容
//获得行的数目
int rowCount = sheet.getPhysicalNumberOfRows();
for(int rowNum = 1; rowNum < rowCount; rowNum++){
Row rowData = sheet.getRow(rowNum);
if(rowData != null){
//获得该行的列的数目
int lineCount = rowData.getPhysicalNumberOfCells();
for(int lineNum = 0; lineNum < lineCount ;lineNum++){
System.out.print("第" + rowNum +"行，第" + lineNum +"列：");
Cell cell = rowData.getCell(lineNum);
//判断数据类型
if(cell != null){
int cellType = cell.getCellType();
switch (cellType){
case XSSFCell.CELL_TYPE_STRING:
System.out.println("字符串：" + cell.getStringCellValue()); break;
case XSSFCell.CELL_TYPE_BOOLEAN:
System.out.println("布尔：" + cell.getBooleanCellValue()); break;
case XSSFCell.CELL_TYPE_BLANK:
System.out.println("空"); break;
case XSSFCell.CELL_TYPE_ERROR:
System.out.println("没有该数据类型"); break;
case XSSFCell.CELL_TYPE_NUMERIC:
//如果是日期就直接输出，否则就装换为String，然后输出
if(HSSFDateUtil.isCellDateFormatted(cell)){
System.out.println("日期格式：" + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")
.format(new Date(String.valueOf(cell.getDateCellValue())))); break;
}else{
cell.setCellType(XSSFCell.CELL_TYPE_STRING);
System.out.println("整型：" + cell.toString()); break;
}
case Cell.CELL_TYPE_FORMULA:
String formula = cell.getCellFormula();
System.out.println("公式：" + formula); break;
default:
System.out.println("该位置没有数据");break;
}
}
}
}
}
fileInputStream.close();
}
}