java操作Excel -- poi支持

poi是apache的子项目，专门用于处理Microsoft文档，其中HSSF和XSSF专门用于操作Excel表格（HSSF操作的是后缀名为.xls的文档（Excel 2003 以上），XSSF操作的是后缀名为.xlsx的文档（Excel 2007））。

所需jar包：poi-3.9-20121203.jar (当前最新jar包)

Tag1：create Excel

/**
* 创建Excle并写入数据
* @author Ye
*
*/
public class CreateExcel {

//测试数据，用于写入到Excel
private static List<Student> getStudent() throws Exception{
List<Student> list = new ArrayList<Student>();
SimpleDateFormat df = new SimpleDateFormat("yyyy-mm-dd");
Student user1 = new Student(1,"张三","男",16,df.parse("1997-03-12"));
Student user2 = new Student(2,"李四","男",17,df.parse("1999-08-12"));
Student user3 = new Student(3,"王五","女",26,df.parse("1985-11-12"));
list.add(user1);
list.add(user2);
list.add(user3);
return list;
}

public static void main(String[] args) throws Exception {
//第一步，创建一个webbook，对应一个Excel文件
HSSFWorkbook wb = new HSSFWorkbook();

//第二步，在webbook中添加一个sheet,对应Excel文件中的sheet
HSSFSheet studentSheet = wb.createSheet("学生信息");

  //第三步，在sheet中添加表头行(即第0行),注意老版本poi对Excel的行数列数限制为short类型
HSSFRow studentHeadRow = studentSheet.createRow(0);

//第四步，创建表头单元格，并设置单元格值居中（方法一:手动设置）
HSSFCellStyle style = wb.createCellStyle();   //创建单元格样式
style.setAlignment(HSSFCellStyle.ALIGN_CENTER); //设置样式为居中显示

HSSFCell studentHeadcell = null;
studentHeadcell = studentHeadRow.createCell(0);
studentHeadcell.setCellValue("学号");
studentHeadcell.setCellStyle(style);
studentHeadcell = studentHeadRow.createCell(1);
studentHeadcell.setCellValue("姓名");
studentHeadcell.setCellStyle(style);
studentHeadcell = studentHeadRow.createCell(2);
studentHeadcell.setCellValue("性别");
studentHeadcell.setCellStyle(style);
studentHeadcell = studentHeadRow.createCell(3);
studentHeadcell.setCellValue("年龄");
studentHeadcell.setCellStyle(style);
studentHeadcell = studentHeadRow.createCell(4);
studentHeadcell.setCellValue("出生年月");
studentHeadcell.setCellStyle(style);

//方法二:通过反射机制获取类中的所有属性并设为表头
//    	     try {
//               Class<?> studentClass = Class.forName("Student");  //com.geocompass.model.STSTBPRPModel
//               Field[] fieldList = studentClass.getDeclaredFields();
//               for (int i = 0; i < fieldList.length; i++) {
//                    Field fld = fieldList[i];
//                    studentHeadRow.createCell(i).setCellValue(fld.getName());
//               }
//            } catch (ClassNotFoundException e) {
//               e.printStackTrace();
//            }

//第五步，写入实体数据
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
List<Student> stuList = CreateExcel.getStudent();  //获取实体数据集
HSSFRow studentRow = null;  //数据行
for(int i=0;i<stuList.size();i++){
studentRow = studentSheet.createRow(i+1);
Student stu = (Student) stuList.get(i);
studentRow.createCell(0).setCellValue(stu.getId());
studentRow.createCell(1).setCellValue(stu.getName());
studentRow.createCell(2).setCellValue(stu.getGender());
studentRow.createCell(3).setCellValue(stu.getAge());
studentRow.createCell(4).setCellValue(sdf.format(stu.getBirth()));
}

//第六步，将文件存到指定位置
try {
FileOutputStream fout = new FileOutputStream("D:/student.xls");
wb.write(fout);
fout.close();
} catch (Exception e) {
e.printStackTrace();
}

//或弹出下载对话框
response.setContentType("application/ms-excel");
             response.setHeader("Content-Disposition" ,"attachment;filename="+new String("导出Excel.xls".getBytes(),"utf-8")) ;
wb.write(response.getOutputStream());
 }
}

Tag2：read from Excel

/**
 * 读取Excel
 * @author Ye
 *
 */
public class ReadExcel {
    
    public static void main(String[] args) throws IOException, ParseException {
        //第一步:初始化Workbook对象。
        HSSFWorkbook wb = new HSSFWorkbook(new FileInputStream("D:/student.xls"));
        List<Student> stuList = new ArrayList<Student>();
        
        //第二步:循环遍历获取Excel的sheet
        for (int sheetNum = 0; sheetNum < wb.getNumberOfSheets(); sheetNum++) {
            HSSFSheet hssfSheet = wb.getSheetAt(sheetNum);
            if (hssfSheet == null) {
                continue;
            }
            
            Student stu = null;
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");

            //第三步:循环遍历获取第sheetNum个sheet的所有行记录
            for (int rowNum = 1; rowNum <= hssfSheet.getLastRowNum(); rowNum++) {
                HSSFRow hssfRow = hssfSheet.getRow(rowNum);
                if (hssfRow == null) {
                    continue;
                }
                
                stu = new Student();
                
                //第四步:获取每个单元格的值并赋值给stu对象
                HSSFCell sid = hssfRow.getCell(0);
                stu.setId(Integer.parseInt(getValue(sid)));
                
                HSSFCell sname = hssfRow.getCell(1);
                stu.setName(getValue(sname));
                
                HSSFCell gender = hssfRow.getCell(2);
                stu.setGender(getValue(gender));
                
                HSSFCell age = hssfRow.getCell(3);
                stu.setAge(Float.parseFloat(getValue(age)));
                
                HSSFCell birth = hssfRow.getCell(4);
                stu.setBirth(sdf.parse(getValue(birth)));

                stuList.add(stu);
            }
        }

       //测试
       for(Student s:stuList)
       {
           System.out.println(s.getId() + "  " + s.getName() +"   " + s.getGender() + "   "+ s.getAge() + "   " + s.getBirth());
       }
        
    }
    
    //将Excel单元格中的数据都转化成String类型
    private static String getValue(HSSFCell hssfCell) {
        if (hssfCell.getCellType() == hssfCell.CELL_TYPE_BOOLEAN) {
            return String.valueOf(hssfCell.getBooleanCellValue());  // 返回布尔类型的值
        } else if (hssfCell.getCellType() == hssfCell.CELL_TYPE_NUMERIC) {
            return String.valueOf(hssfCell.getNumericCellValue()); // 返回数值类型的值
        } else {
            return String.valueOf(hssfCell.getStringCellValue());  // 返回字符串类型的值
        }
    }

}

Notice：(1) 之前我一直使用Tomcat服务器运行代码，也没出过错，最近换成用Weblogic服务器，运行该代码时却报错：

java.lang.NoClassDefFoundError: org/apache/poi/hssf/usermodel/HSSFWorkbook

java.lang.ClassNotFoundException: org.apache.poi.hssf.usermodel.HSSFWorkbook

但明明都把poi-3.9-20121203.jar都已放到lib目录下，程序也都是自动部署的，为什么会找不到该jar包中的类呢？赶紧到weblogic服务器的部署目录（D:\Tool\bea\user_projects\domains\base_domain\servers\AdminServer\tmp\_WL_user\CMDB\i3s8gk\war\WEB-INF\lib）去看，果然没给我自动编译加载过来，重启下服务器，问题解决！