java实现本地excel读取与导出

1. 添加jar包
   poi-3.10.jar
2. 导出excel

import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;


public class ExportExcel {
	private static String[] header = { "姓名", "年龄" };
	public static void main(String[] args) throws IOException {
		List list = new ArrayList();
		for(int i=0;i<20;i++){//创建导出数据
			Excel excelDemo = new ExportExcel().new Excel();
			excelDemo.setName("name"+i);
			excelDemo.setAge("age"+i);
			list.add(excelDemo);
		}
		HSSFWorkbook workBook = new HSSFWorkbook();// 创建一个Excel工作薄
		HSSFSheet sheet = workBook.createSheet("sheet1");
		
		HSSFRow headerRow = sheet.createRow(0);// 创建首行，并赋值
		HSSFFont headFont = workBook.createFont();  
		headFont.setFontName("仿宋_GB2312");
		headFont.setFontHeightInPoints((short) 12);
		headFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
        HSSFCellStyle style = workBook.createCellStyle();
        style.setFont(headFont);
		headerRow.setRowStyle(style);
		for (int i = 0; i < header.length; i++) {//给首行赋值
			headerRow.createCell(i).setCellValue(header[i]);
			sheet.setColumnWidth(i, 255 * 15);
		}
		for (int j = 0; j < list.size(); j++) {//给数据行赋值
			HSSFRow row = sheet.createRow(j+1);
			row.createCell(0).setCellValue(list.get(j).name);
			row.createCell(1).setCellValue(list.get(j).age);
		}
		
		ByteArrayOutputStream os = new ByteArrayOutputStream();// 将Excel文件存在输出流中
		workBook.write(os);// 将Excel写入输出流中
		byte[] fileContent = os.toByteArray();// 将输出流转换成字节数组
		os.close();
		OutputStream out = new FileOutputStream("D:\\javertWang.xls");
		out.write(fileContent);
		out.close();
	}
	class Excel{
		private String name;
		private String age;
		public String getName() {
			return name;
		}
		public void setName(String name) {
			this.name = name;
		}
		public String getAge() {
			return age;
		}
		public void setAge(String age) {
			this.age = age;
		}
	}

}

3.读取Excel

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

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

public class ImportExcel {

    public static void main(String[] args) {
        Workbook wb =null;
        Sheet sheet = null;
        Row row = null;
        List> list = null;
        String cellData = null;
        String filePath = "D:\\javertWang.xls";
        String columns[] = {"name","age"};
        wb = readExcel(filePath);
        if(wb != null){
            //用来存放表中数据
            list = new ArrayList>();
            //获取第一个sheet
            sheet = wb.getSheetAt(0);
            //获取最大行数
            int rownum = sheet.getPhysicalNumberOfRows();
            //获取第一行
            row = sheet.getRow(0);
            //获取最大列数
            int colnum = row.getPhysicalNumberOfCells();
            for (int i = 1; i map = new LinkedHashMap();
                row = sheet.getRow(i);
                if(row !=null){
                    for (int j=0;j map : list) {
            for (Entry entry : map.entrySet()) {
                System.out.print(entry.getKey()+":"+entry.getValue()+",");
            }
            System.out.println();
        }

    }
    //读取excel
    public static Workbook readExcel(String filePath){
        Workbook wb = null;
        if(filePath==null){
            return null;
        }
        String extString = filePath.substring(filePath.lastIndexOf("."));
        InputStream is = null;
        try {
            is = new FileInputStream(filePath);
            if(".xls".equals(extString)){
                return wb = new HSSFWorkbook(is);
            }else{
                return wb = null;
            }
            
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return wb;
    }
    public static Object getCellFormatValue(Cell cell){
        Object cellValue = null;
        if(cell!=null){
            //判断cell类型
            switch(cell.getCellType()){
            case Cell.CELL_TYPE_NUMERIC:{
                cellValue = String.valueOf(cell.getNumericCellValue());
                break;
            }
            case Cell.CELL_TYPE_FORMULA:{
                //判断cell是否为日期格式
                if(DateUtil.isCellDateFormatted(cell)){
                    //转换为日期格式YYYY-mm-dd
                    cellValue = cell.getDateCellValue();
                }else{
                    //数字
                    cellValue = String.valueOf(cell.getNumericCellValue());
                }
                break;
            }
            case Cell.CELL_TYPE_STRING:{
                cellValue = cell.getRichStringCellValue().getString();
                break;
            }
            default:
                cellValue = "";
            }
        }else{
            cellValue = "";
        }
        return cellValue;
    }

}