怎么生成可变表头的excel

filePath=E\:/appData

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));    }}