java poi 读取excel

一般遍历使用两种方式，1：得到总的行数和每行的列数，然后循环。2：使用迭代
先看第一种：
Java代码 
package com.golden.test; 
 
import java.io.File; 
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; 
 
/**
* 
* @author 崔素强
* 
*/ 
public class PoiReadXls2 { 
    public static void main(String[] args) { 
        File f = new File("c:\\a.xls"); 
        try { 
            FileInputStream is = new FileInputStream(f); 
            HSSFWorkbook wbs = new HSSFWorkbook(is); 
            HSSFSheet childSheet = wbs.getSheetAt(0); 
            // System.out.println(childSheet.getPhysicalNumberOfRows()); 
            System.out.println("有行数" + childSheet.getLastRowNum()); 
            for (int j = 0; j < childSheet.getLastRowNum(); j++) { 
                HSSFRow row = childSheet.getRow(j); 
                // System.out.println(row.getPhysicalNumberOfCells()); 
                // System.out.println("有列数" + row.getLastCellNum()); 
                if (null != row) { 
                    for (int k = 0; k < row.getLastCellNum(); k++) { 
                        HSSFCell cell = row.getCell(k); 
                        if (null != cell) { 
                            switch (cell.getCellType()) { 
                            case HSSFCell.CELL_TYPE_NUMERIC: // 数字 
                                System.out.print(cell.getNumericCellValue() 
                                        + "   "); 
                                break; 
                            case HSSFCell.CELL_TYPE_STRING: // 字符串 
                                System.out.print(cell.getStringCellValue() 
                                        + "   "); 
                                break; 
                            case HSSFCell.CELL_TYPE_BOOLEAN: // Boolean 
                                System.out.println(cell.getBooleanCellValue() 
                                        + "   "); 
                                break; 
                            case HSSFCell.CELL_TYPE_FORMULA: // 公式 
                                System.out.print(cell.getCellFormula() + "   "); 
                                break; 
                            case HSSFCell.CELL_TYPE_BLANK: // 空值 
                                System.out.println(" "); 
                                break; 
                            case HSSFCell.CELL_TYPE_ERROR: // 故障 
                                System.out.println(" "); 
                                break; 
                            default: 
                                System.out.print("未知类型   "); 
                                break; 
                            } 
                        } else { 
                            System.out.print("-   "); 
                        } 
                    } 
                } 
                System.out.println(); 
            } 
        } catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
} 

得到Excel的文件然后读取，这个很简单。关键有两个地方，也许在网上会看到有的这样使用有的那样使用。
System.out.println("有行数" + childSheet.getLastRowNum());
System.out.println(childSheet.getPhysicalNumberOfRows());
System.out.println("有列数" + row.getLastCellNum());
System.out.println(row.getPhysicalNumberOfCells());
如果人都拷贝代码进行使用了，不知道有什么区别。太多的区别不知道，但是有一点我发现了，那就是如果中间各行或者隔列的话getPhysicalNumberOfRows和getPhysicalNumberOfCells就不能读取到所有的行和列了。
再者，一定要对单元格的格式进行判断switch (cell.getCellType())，不同的单元格格式使用不同的方法。最后加上为止类型，以防万一。
而且在数字类型里，又分为了纯数字和时间格式：
Java代码 
case HSSFCell.CELL_TYPE_NUMERIC: // 数值型 
    if (HSSFDateUtil.isCellDateFormatted(cell)) { 
        //  如果是date类型则 ，获取该cell的date值 
        value = HSSFDateUtil.getJavaDate(cell.getNumericCellValue()).toString(); 
    } else { // 纯数字 
        value = String.valueOf(cell.getNumericCellValue()); 
} 

还有一种迭代的方法：
Java代码 
package com.golden.test; 
 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.util.Iterator; 
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; 
 
/**
* 
* @author 崔素强
* 
*/ 
public class PoiReadXls { 
    @SuppressWarnings( { "unchecked", "deprecation" }) 
    public static void main(String[] args) { 
        File f = new File("c:\\a.xls"); 
        try { 
            InputStream input = new FileInputStream(f); 
            POIFSFileSystem fs = new POIFSFileSystem(input); 
            HSSFWorkbook wb = new HSSFWorkbook(fs); 
            HSSFSheet sheet = wb.getSheetAt(0); 
            Iterator rows = sheet.rowIterator(); 
            while (rows.hasNext()) { 
                HSSFRow row = (HSSFRow) rows.next(); 
                // System.out.print("行：" + row.getRowNum() + " "); 
                Iterator cells = row.cellIterator(); 
                while (cells.hasNext()) { 
                    HSSFCell cell = (HSSFCell) cells.next(); 
                    // System.out.println("列：" + cell.getCellNum()); 
                    switch (cell.getCellType()) { 
                    case HSSFCell.CELL_TYPE_NUMERIC: // 数字 
                        System.out.print(cell.getNumericCellValue() + "   "); 
                        break; 
                    case HSSFCell.CELL_TYPE_STRING: // 字符串 
                        System.out.print(cell.getStringCellValue() + "   "); 
                        break; 
                    case HSSFCell.CELL_TYPE_BOOLEAN: // Boolean 
                        System.out.println(cell.getBooleanCellValue() + "   "); 
                        break; 
                    case HSSFCell.CELL_TYPE_FORMULA: // 公式 
                        System.out.print(cell.getCellFormula() + "   "); 
                        break; 
                    case HSSFCell.CELL_TYPE_BLANK: // 空值 
                        System.out.println(" "); 
                        break; 
                    case HSSFCell.CELL_TYPE_ERROR: // 故障 
                        System.out.println(" "); 
                        break; 
                    default: 
                        System.out.print("未知类型   "); 
                        break; 
                    } 
                } 
                System.out.println(); 
            } 
        } catch (IOException ex) { 
            ex.printStackTrace(); 
        } 
    } 
} 

这种方法，如果数据的紧凑的，使用还是方便的，但是我发现，如果是空行或者是空列，他就会隔过去。具体的自己试试就知道了。
另外，也能看到这里得到Excel文件的方式是通过File，如果要引用到Struts2里，这是很简单的，因为Struts2上传时Action里定义的就是File或者File数组。