java如何生成可变表头的excel

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

public class GetFilePlace 
{
 /**
  * 读取文件，获取excel保存的根目录
  * @return excel保存的根目录
  */
 public String getFilePath()
 {
  String dir = System.getProperty("user.dir"); //获得tomcat所在的工作路径 
  
  //获取到存储了文件存储位置的filedir.properties 文件路径
  String realDir = dir + File.separator + "src" + File.separator +"META-INF" + File.separator + "filedir.properties";
  
  /*String realDir = dir.substring(0, dir.length()-4) + File.separator +"webapps" + File.separator + "generateExcels" 
      + File.separator + "classes" + File.separator + "META-INF" + File.separator + "config" + File.separator + "filedir.properties";
 */
  return realDir;
 }
 
 /**
  * 获取filePath路径【properities文件】中key对应的值，
  * @param filePath properities文件路径【包含properities文件】
  * @param key 要查找的key值
  * @return key对应的value
  */
  public String GetValueByKey(String filePath, String key) 
  {
   Properties pps = new Properties();
   try {
    InputStream in = new BufferedInputStream (new FileInputStream(filePath)); 
    pps.load(in);
    String value = pps.getProperty(key);
    in.close();
    return value;
    
   }catch (IOException e) {
    e.printStackTrace();
    return null;
   }
  }
 
 /**
  * 查询properities文件中可以对应的存储地点
  * @param key 查询主键
  * @return key对应的存储地址
  */
 public String getFileDirFromProperties(String key)
 {
  return GetValueByKey(getFilePath(),key);
 }
 
 public static void main(String[] args)
 {
  System.out.println(new GetFilePlace().getFileDirFromProperties("filePath"));
 }
}

import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class GenerateFold
{
 /**
  * 查询当前生成的excel需要存在在哪个路径，如果存在则存储在相应的位置，否则生成改目录， 每天生成一个文件夹，文件夹的命名规则为 年月日的时间戳
  * @param foldName 生成excel保存路径
  * @return   现在的excel需要保存路径
  */
 public String getFold(String foldName)
 {
  SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd");
  
  String todayStr = format.format(Calendar.getInstance().getTime());
  
  String foldPath = foldName + File.separator + todayStr; 
  
  File file = new File(foldPath);
  
  if(!file.exists() && !file.isDirectory())
  {
   System.out.println("不存在");
   file.mkdirs();
  }
  else
  {
   System.out.println("存在");
  }
  return foldPath;
 }

}

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.UUID;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
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.hssf.util.Region;
import org.apache.poi.ss.usermodel.CellStyle;

import com.zcr.until.GetFilePlace;
import com.zcr.until.User;

/**
 * 生成excel
 * @author zcr
 *
 */
public class GenerateExcel
{
 /**
  * 通过关键字查询properties文件相应文件的存储位置，根据表头顺序将数据保存到相应文件路径的xls文件中, 文件的命名规则是时间戳加一串全球唯一编码
  * @param fileDir       //查找文件存储根目录
  * @param head       //表头
  * @param list       //数据
  * @return        //文件的保存路径及其名字的字符串
  */
 public <T> String generateExcels(String fileDir,String [] head,List<T> list) 
 {
  //获得存储的路径
  //String savePath = new GetFilePlace().getFileDirFromProperties(key);
  
  //文件存储名字
  String saveFileName = "";
  SimpleDateFormat format = new SimpleDateFormat("yyyyMMddHHmmssSS");
  saveFileName += format.format(Calendar.getInstance().getTime());
  
  UUID uuid = UUID.randomUUID(); //全球唯一编码
  
  saveFileName += "-" + uuid.toString();
  
  
  HSSFWorkbook workbook = new HSSFWorkbook();
  HSSFSheet sheet = workbook.createSheet();
  workbook.setSheetName(0,"APP数据"); //设置表格工作簿名称
  HSSFCellStyle cellStyle = workbook.createCellStyle();
  cellStyle.setAlignment(CellStyle.ALIGN_CENTER);
  cellStyle.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
  
  HSSFRow titleRow = sheet.createRow(0);
  sheet.addMergedRegion(new Region(0,(short)0,0,(short)(head.length-1)));
  HSSFCell titleCell = titleRow.createCell(0);
  titleCell.setCellValue("AAP数据____ ");
  titleCell.setCellStyle(cellStyle);
  HSSFRow row1 = sheet.createRow(1);
  
  
  //设置表头
  for(int i = 0 ; i < head.length ; i++)
  {
   HSSFCell cell = row1.createCell(i);
   cell.setCellValue(head[i]); //设置值
   cell.setCellStyle(cellStyle);//设置样式
  }
  
  
  if(null != list && list.size() > 0)
  {
   int size = list.size(); 
   Class classType = list.get(0).getClass();
   for(int i = 0,rowNum=2 ; i < size ; i ++,rowNum++)
   {
    HSSFRow rows = sheet.createRow(rowNum);
    T t = list.get(i);
    
    //添加数据行
    for(int j = 0 ; j < head.length ; j++) 
    {
     //获得首字母
     String firstLetter = head[j].substring(0,1).toUpperCase(); 
     
     //获得get方法,getName,getAge等
     String getMethodName = "get" + firstLetter + head[j].substring(1);
     
     Method method;
     try
     {
      //通过反射获得相应的get方法，用于获得相应的属性值
      method = classType.getMethod(getMethodName, new Class[]{});
      
      HSSFCell dataCell = rows.createCell(j);
      try
      {
        System.out.print(getMethodName +":" + method.invoke(t, new Class[]{}) +",");
        dataCell.setCellValue(method.invoke(t, new Class[]{}).toString());
      }
      catch (IllegalArgumentException e)
      {
       e.printStackTrace();
      }
      catch (IllegalAccessException e)
      {
       e.printStackTrace();
      }
      catch (InvocationTargetException e)
      {
       e.printStackTrace();
      } //设置值
      dataCell.setCellStyle(cellStyle);//设置样式
     }
     catch (SecurityException e)
     {
      e.printStackTrace();
     }
     catch (NoSuchMethodException e)
     {
      e.printStackTrace();
     }
     
    }
    System.out.println();
   }
  }
  else
  {
   System.out.println("没有数据");
  }
  
  //获得文件存储路径
  //String fileDir = new GetFilePlace().getFileDirFromProperties(key);
  saveFileName += ".xls";
  String saveFilePathAndName = fileDir + File.separator + saveFileName;
  OutputStream out = null;
  try
  {
   out = new FileOutputStream(saveFilePathAndName);
   try
   {
    workbook.write(out);//保存文件
   }
   catch (IOException e)
   {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
  catch (FileNotFoundException e)
  {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  finally
  {
   try
   {
    out.close();
   }
   catch (IOException e)
   {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
  
  return saveFilePathAndName;
 }

 
 /**
  * 提供外界调用的接口，生成以head为表头，list为数据的excel
  * @param head //数据表头
  * @param list //数据
  * @return  //excel所在的路径
  */
 public <T> String generateExcel(String [] head,List<T> list)
 {
  final String FilePath = "filePath";
  String saveFilePathAndName = "";
 
  //获得存储的根目录
  String savePath = new GetFilePlace().getFileDirFromProperties(FilePath);
  
  //获得当天存储的路径
  String realSavePath = new GenerateFold().getFold(savePath);
  
  //生成excel并将存储的路径返回（包含文件名）
  saveFilePathAndName = generateExcels(realSavePath, head, list);
  
  return saveFilePathAndName;
 }
 
 
 public static void main(String[] args)
 {
  String [] head = {"name","sex","adress","height","age","jj"};
  
  List<User> list = new ArrayList<User>();
  User user1 = new User("zhangsan",1,1.1f,"北京","男","AA");
  User user2 = new User("lisi",22222,3.2f,"上海","女","BB");
  
  list.add(user1);
  list.add(user2);
  
  System.out.println(new GenerateExcel().generateExcel(head,list));
  //System.out.println(new GenerateExcel().generateExcels("E:\\appData\\20151104",head,list));
 }

}