（七）POI-讀取excel，遍歷一個工作簿

原文鏈接：https://blog.csdn.net/class157/article/details/92816169，https://blog.csdn.net/class157/article/details/93237963

package cases;

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;
import org.apache.poi.ss.usermodel.*;
import org.testng.annotations.Test;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * @description:
 * @author: lv
 * @time: 2020/5/22 14:21
 */
public class DemoTest {

    @Test
    public void testPoi()throws IOException {
        //建立輸入流
        InputStream is = new FileInputStream("D:\\3.xls");
        //接受一個輸入流
        POIFSFileSystem fs = new POIFSFileSystem(is);
        //創建了一個工作簿
        HSSFWorkbook wb = new HSSFWorkbook(fs);
        //獲取第一個sheet頁
        HSSFSheet hssfSheet = wb.getSheetAt(0);
        //判斷Sheet是否為空
        if (hssfSheet == null) {
            return;
        }
        //遍歷行row
        //continue只是終止本次循環，接着還執行后面的循環
        for (int rownum = 0; rownum <= hssfSheet.getLastRowNum(); rownum++) {
            //獲取到每一行
            HSSFRow sheetRow = hssfSheet.getRow(rownum);
            if (sheetRow == null) {
                continue;
            }
            //遍歷列cell
            for (int cellnum = 0; cellnum <= sheetRow.getLastCellNum(); cellnum++) {
                HSSFCell cell = sheetRow.getCell(cellnum);
                if (cell == null) {
                    continue;
                }
                //獲取單元格的值
                System.out.print(" " + getValue(cell));
            }
        }
    }
private static String getValue(HSSFCell hssfCell) {
    String cellValue = "";
    if(hssfCell == null){
        return cellValue;
    }
    //把數字當成String來讀，避免出現1讀成1.0的情況
    hssfCell.setCellType(CellType.STRING);

    //hssfCell.getCellType() 獲取當前列的類型
    if (hssfCell.getCellType() == CellType.BOOLEAN) {
        cellValue = String.valueOf(hssfCell.getBooleanCellValue());
    }else if (hssfCell.getCellType() == CellType.NUMERIC) {
        cellValue =  String.valueOf(hssfCell.getNumericCellValue());
    }else if(hssfCell.getCellType() == CellType.STRING){
        cellValue =  String.valueOf(hssfCell.getStringCellValue());
    }else if(hssfCell.getCellType() == CellType.FORMULA){
        cellValue =  String.valueOf(hssfCell.getCellFormula());
    }else if (hssfCell.getCellType() == CellType.BLANK){
        cellValue = " ";
    }else if(hssfCell.getCellType() == CellType.ERROR){
        cellValue = "非法字符";
    }else{
        cellValue = "未知類型";
    }
    return cellValue;
}
}

注意點：

調用方式被棄用 
cell.setCellType(HSSFCell.CELL_TYPE_NUMERIC);
可以使用這個 
cell.setCellType(CellType.NUMERIC);