Poi基础

①：向excel输出东西

package poi;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

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;

public class Demo1 implements Runnable{

    public static void main(String[] args) throws Exception {
        Demo1 demo1=new Demo1();
        Thread thread=new Thread(demo1);
        thread.start();

    }

    @Override
    public void run() {
        Workbook wb=new HSSFWorkbook();
        FileOutputStream outputStream = null;
        try {
            outputStream = new FileOutputStream("E://poi.xls");  //文件位置
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        Sheet sheet=wb.createSheet();  //创建一页
        Row row=sheet.createRow(0);   //创建一行（第一行）
        Cell cell1=row.createCell(0);  //创建一列（第一列）
        Cell cell2=row.createCell(1);
        SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        cell1.setCellValue(format.format(new Date()));
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        cell2.setCellValue(format.format(new Date()));
        System.out.println("!!!!");
        try {
            wb.write(outputStream);  //向工作簿写东西
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            try {
                outputStream.close();  // 关闭流
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

②：poi处理日期：

package poi;

import java.io.FileOutputStream;
import java.util.Calendar;
import java.util.Date;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.CreationHelper;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;

public class Demo2 {

    public static void main(String[] args) throws Exception {
        Workbook wb=new HSSFWorkbook();
        FileOutputStream outputStream=new FileOutputStream("E://poi2.xls");
        Sheet sheet=wb.createSheet();
        Row row=sheet.createRow(0);
        Cell cell=row.createCell(0);
        cell.setCellValue(new Date());

        //第一种方法
        CreationHelper helper=wb.getCreationHelper();
        CellStyle cellStyle=wb.createCellStyle();
        cellStyle.setDataFormat(helper.createDataFormat().getFormat("yyyy-MM-dd HH:mm:ss"));
        cell=row.createCell(1);
        cell.setCellValue(new Date());
        cell.setCellStyle(cellStyle);

        //第二种方法
        cell=row.createCell(2);
        cell.setCellValue(Calendar.getInstance());
        cell.setCellStyle(cellStyle);

        wb.write(outputStream);
        outputStream.close();

    }
}

③：利用for循环遍历

package poi;

import java.io.FileInputStream;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;

public class Demo3 {

    public static void main(String[] args) throws Exception {
        FileInputStream inputStream=new FileInputStream("E://poi.xls");
        POIFSFileSystem fs=new POIFSFileSystem(inputStream);
        HSSFWorkbook wb=new HSSFWorkbook(fs);  //获取工作簿
        HSSFSheet sheet=wb.getSheetAt(0);  //获取第一页
        if(sheet==null){
            return;
        }
        //循环遍历所有的行
        for(int rowNum=0;rowNum<=sheet.getLastRowNum();rowNum++){
            HSSFRow row=sheet.getRow(rowNum);
            //如果行为空就跳过
            if(row==null){
                continue;
            }
            //循环遍历所有的列
            for(int cellNum=0;cellNum<=row.getLastCellNum();cellNum++){
                HSSFCell cell=row.getCell(cellNum);
                //如果行为列就跳过
                if(cell==null){
                    continue;
                }
                System.out.print(" "+getValue(cell));
            }
            System.out.println();
        }
    }

    //获取并处理单元格的值
    private static String getValue(HSSFCell hssfCell){
        if(hssfCell.getCellType()==HSSFCell.CELL_TYPE_BOOLEAN){
            return String.valueOf(hssfCell.getBooleanCellValue()); //boolean类型
        }else if(hssfCell.getCellType()==HSSFCell.CELL_TYPE_NUMERIC){
            return String.valueOf(hssfCell.getNumericCellValue());  //数字型
        }else{
            return String.valueOf(hssfCell.getStringCellValue());  //字符串型
        }
    }
}

④：不用for循环遍历

package poi;

import java.io.FileInputStream;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.ss.extractor.ExcelExtractor;

public class Demo4 {

    public static void main(String[] args) throws Exception {
        FileInputStream inputStream=new FileInputStream("E://poi.xls");
        POIFSFileSystem fs=new POIFSFileSystem(inputStream);
        HSSFWorkbook wb=new HSSFWorkbook(fs);

        ExcelExtractor extractor=new org.apache.poi.hssf.extractor.ExcelExtractor(wb);
        System.out.println(extractor.getText());
    }
}