excel操作

1.前言

项目中要求读取excel文件内容，并将其转化为xml格式。常见读取excel文档一般使用POI和JExcelAPI这两个工具。这里我们介绍使用POI实现读取excel文档。

2.代码实例：


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package edu.sjtu.erplab.poi;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
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;

/**
* 操作Excel表格的功能类
*/
public class ExcelReader {
    private POIFSFileSystem fs;
    private HSSFWorkbook wb;
    private HSSFSheet sheet;
    private HSSFRow row;

    /**
     * 读取Excel表格表头的内容
     * @param InputStream
     * @return String 表头内容的数组
     */
    public String[] readExcelTitle(InputStream is) {
        try {
            fs = new POIFSFileSystem(is);
            wb = new HSSFWorkbook(fs);
        } catch (IOException e) {
            e.printStackTrace();
        }
        sheet = wb.getSheetAt(0);
        row = sheet.getRow(0);
        // 标题总列数
        int colNum = row.getPhysicalNumberOfCells();
        System.out.println("colNum:" + colNum);
        String[] title = new String[colNum];
        for (int i = 0; i < colNum; i++) {
            //title[i] = getStringCellValue(row.getCell((short) i));
            title[i] = getCellFormatValue(row.getCell((short) i));
        }
        return title;
    }

    /**
     * 读取Excel数据内容
     * @param InputStream
     * @return Map 包含单元格数据内容的Map对象
     */
    public Map<Integer, String> readExcelContent(InputStream is) {
        Map<Integer, String> content = new HashMap<Integer, String>();
        String str = "";
        try {
            fs = new POIFSFileSystem(is);
            wb = new HSSFWorkbook(fs);
        } catch (IOException e) {
            e.printStackTrace();
        }
        sheet = wb.getSheetAt(0);
        // 得到总行数
        int rowNum = sheet.getLastRowNum();
        row = sheet.getRow(0);
        int colNum = row.getPhysicalNumberOfCells();
        // 正文内容应该从第二行开始,第一行为表头的标题
        for (int i = 1; i <= rowNum; i++) {
            row = sheet.getRow(i);
            int j = 0;
            while (j < colNum) {
                // 每个单元格的数据内容用"-"分割开，以后需要时用String类的replace()方法还原数据
                // 也可以将每个单元格的数据设置到一个javabean的属性中，此时需要新建一个javabean
                // str += getStringCellValue(row.getCell((short) j)).trim() +
                // "-";
                str += getCellFormatValue(row.getCell((short) j)).trim() + "    ";
                j++;
            }
            content.put(i, str);
            str = "";
        }
        return content;
    }

    /**
     * 获取单元格数据内容为字符串类型的数据
     *
     * @param cell Excel单元格
     * @return String 单元格数据内容
     */
    private String getStringCellValue(HSSFCell cell) {
        String strCell = "";
        switch (cell.getCellType()) {
        case HSSFCell.CELL_TYPE_STRING:
            strCell = cell.getStringCellValue();
            break;
        case HSSFCell.CELL_TYPE_NUMERIC:
            strCell = String.valueOf(cell.getNumericCellValue());
            break;
        case HSSFCell.CELL_TYPE_BOOLEAN:
            strCell = String.valueOf(cell.getBooleanCellValue());
            break;
        case HSSFCell.CELL_TYPE_BLANK:
            strCell = "";
            break;
        default:
            strCell = "";
            break;
        }
        if (strCell.equals("") || strCell == null) {
            return "";
        }
        if (cell == null) {
            return "";
        }
        return strCell;
    }

    /**
     * 获取单元格数据内容为日期类型的数据
     *
     * @param cell
     *            Excel单元格
     * @return String 单元格数据内容
     */
    private String getDateCellValue(HSSFCell cell) {
        String result = "";
        try {
            int cellType = cell.getCellType();
            if (cellType == HSSFCell.CELL_TYPE_NUMERIC) {
                Date date = cell.getDateCellValue();
                result = (date.getYear() + 1900) + "-" + (date.getMonth() + 1)
                        + "-" + date.getDate();
            } else if (cellType == HSSFCell.CELL_TYPE_STRING) {
                String date = getStringCellValue(cell);
                result = date.replaceAll("[年月]", "-").replace("日", "").trim();
            } else if (cellType == HSSFCell.CELL_TYPE_BLANK) {
                result = "";
            }
        } catch (Exception e) {
            System.out.println("日期格式不正确!");
            e.printStackTrace();
        }
        return result;
    }

    /**
     * 根据HSSFCell类型设置数据
     * @param cell
     * @return
     */
    private String getCellFormatValue(HSSFCell cell) {
        String cellvalue = "";
        if (cell != null) {
            // 判断当前Cell的Type
            switch (cell.getCellType()) {
            // 如果当前Cell的Type为NUMERIC
            case HSSFCell.CELL_TYPE_NUMERIC:
            case HSSFCell.CELL_TYPE_FORMULA: {
                // 判断当前的cell是否为Date
                if (HSSFDateUtil.isCellDateFormatted(cell)) {
                    // 如果是Date类型则，转化为Data格式
                   
                    //方法1：这样子的data格式是带时分秒的：2011-10-12 0:00:00
                    //cellvalue = cell.getDateCellValue().toLocaleString();
                   
                    //方法2：这样子的data格式是不带带时分秒的：2011-10-12
                    Date date = cell.getDateCellValue();
                    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
                    cellvalue = sdf.format(date);
                   
                }
                // 如果是纯数字
                else {
                    // 取得当前Cell的数值
                    cellvalue = String.valueOf(cell.getNumericCellValue());
                }
                break;
            }
            // 如果当前Cell的Type为STRIN
            case HSSFCell.CELL_TYPE_STRING:
                // 取得当前的Cell字符串
                cellvalue = cell.getRichStringCellValue().getString();
                break;
            // 默认的Cell值
            default:
                cellvalue = " ";
            }
        } else {
            cellvalue = "";
        }
        return cellvalue;

    }

    public static void main(String[] args) {
        try {
            // 对读取Excel表格标题测试
            InputStream is = new FileInputStream("d:\\test2.xls");
            ExcelReader excelReader = new ExcelReader();
            String[] title = excelReader.readExcelTitle(is);
            System.out.println("获得Excel表格的标题:");
            for (String s : title) {
                System.out.print(s + " ");
            }

            // 对读取Excel表格内容测试
            InputStream is2 = new FileInputStream("d:\\test2.xls");
            Map<Integer, String> map = excelReader.readExcelContent(is2);
            System.out.println("获得Excel表格的内容:");
            for (int i = 1; i <= map.size(); i++) {
                System.out.println(map.get(i));
            }

        } catch (FileNotFoundException e) {
            System.out.println("未找到指定路径的文件!");
            e.printStackTrace();
        }
    }
}

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3.总结

因为excel单元格中的内容往往都有一定的格式，比如日期型，数字型，字符串型，因此在读取的时候要进行格式判断，不然会出现错误。常见的就是不能正常读取日期。在代码实例中有一个方法：

getCellFormatValue(HSSFCell cell)

往这个方法中传入excel单元格就能识别单元格格式，并转化为正确的格式。

ps：2012-2-23

代码实例中有一段代码：

int colNum = row.getPhysicalNumberOfCells();

其中的HSSFRow.getPhysicalNumberOfCells();这个方法是用于获取一行中存在的单元格数，POI的官方API中有给出getPhysicalNumberOfCells方法的解释

getPhysicalNumberOfCells
public int getPhysicalNumberOfCells()
gets the number of defined cells (NOT number of cells in the actual row!). That is to say if only columns 0,4,5 have values then there would be 3.Specified by:getPhysicalNumberOfCells in interface RowReturns:int representing the number of defined cells in the row.