poi导出excel，基于模板的比较简单，这个列是动态的，所已选择不基于模板的，相对复杂些，要设置样式。包括：设置列宽、设置字体、设置边框

package com.urthink.jxsh.util;import java.io.FileOutputStream;
import java.lang.reflect.Field;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;
import java.util.List;
import java.util.Map;import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Font;
import org.apache.poi.ss.usermodel.IndexedColors;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;/*** 导出excel* @author happyqing* @date 2017-09-18*/
public class ExcelExport {/*** 导出excel* @param list                数据列表 List<E> 实体类列表* @param headers           列标题，以英文逗号分割，必传* @param includes      属性，以英文逗号分割，必传* @param filePath           导出文件全路径* @param sheetName          sheet名称：sheet1* @param dataPattern      日期格式：yyyy-MM-dd HH:mm:ss* @throws Exception     另一个程序正在使用此文件，进程无法访问*/public static <E> void exportListEntity(List<E> list, String headers, String includes, String filePath, String sheetName, String dataPattern) throws Exception{//工作簿Workbook wb;// 创建模板工作表if (filePath.endsWith(".xls")) {wb = new HSSFWorkbook();} else {//templatewb = new XSSFWorkbook(new FileInputStream(filePath));//wb = new XSSFWorkbook();wb = new SXSSFWorkbook(1000); //大于1000行时会把之前的行写入硬盘，解决内存溢出}String[] headerArr = headers.split(",");String[] includeArr = includes.split(",");List<String> includeList = Arrays.asList(includeArr);;//字体Font font = wb.createFont();   //font.setFontHeightInPoints((short)14);   //font.setColor(IndexedColors.DARK_BLUE.getIndex());   font.setBoldweight(Font.BOLDWEIGHT_BOLD);//样式CellStyle styleBOLD = createBorderedStyle(wb);styleBOLD.setFont(font);styleBOLD.setVerticalAlignment(CellStyle.VERTICAL_CENTER);styleBOLD.setWrapText(false); //自动换行//样式CellStyle styleWrap = createBorderedStyle(wb);styleWrap.setWrapText(false);styleWrap.setVerticalAlignment(CellStyle.VERTICAL_TOP);//表Sheet sheet = wb.createSheet(sheetName);//列宽//sheet.autoSizeColumn(( short ) 0 ); // 调整第一列宽度//sheet.SetColumnWidth(1, 50 * 256);  //设置列宽，50个字符宽度。宽度参数为1/256，故乘以256，中文的要再乘以2
//        sheet.setColumnWidth(0, 3000);//行Row row = sheet.createRow(0);//单元格Cell cell;//写入标题行for(int i=0; i<headerArr.length; i++){cell = row.createCell(i);cell.setCellValue(headerArr[i]);cell.setCellStyle(styleBOLD);}//写入数据E e;           //实体类Field[] fields;    //属性数组Field field;  //属性Object value;   //属性值DateFormat dtf = new SimpleDateFormat(dataPattern); //yyyy-MM-dd HH:mm:ssfor(int i=0; i<list.size(); i++){row = sheet.createRow(i+1);e = list.get(i);// 利用反射，获取属性数组fields = e.getClass().getDeclaredFields();for(int f=0,c=0; f<fields.length; f++){field = fields[f];if(includeList.contains(field.getName())){cell = row.createCell(c);cell.setCellStyle(styleWrap);//cell.setCellType(Cell.CELL_TYPE_STRING);//field.getName();//field.getType();field.setAccessible(true);  //设置些属性是可以访问的value = field.get(e);     //得到此属性的值//Byte,Short,Int,Long,Float,Double,Boolean,Char, String,Date,BigDecimal,byte[]//cell.setCellValue: boolean,Calendar,Date,double,RichTextString,Stringif(value==null){} else if (value instanceof Date){  cell.setCellValue(dtf.format((Date)value));} else {cell.setCellValue(value.toString());}c++;}}}//写入文件FileOutputStream fOut = new FileOutputStream(filePath);wb.write(fOut);}/*** 导出excel* @param list               数据列表 List<Map<String, Object>>* @param headers         列标题，以英文逗号分割，必传* @param includes          字段名，以英文逗号分割，必传* @param filePath          导出文件全路径* @param sheetName          sheet名称：sheet1* @param dataPattern      日期格式：yyyy-MM-dd HH:mm:ss* @throws Exception     另一个程序正在使用此文件，进程无法访问*/public static void exportListMap(List<Map<String, Object>> list, String headers, String includes, String filePath, String sheetName, String dataPattern) throws Exception{//工作簿Workbook wb;// 创建模板工作表if (filePath.endsWith(".xls")) {wb = new HSSFWorkbook();} else {//templatewb = new XSSFWorkbook(new FileInputStream(filePath));//wb = new XSSFWorkbook();wb = new SXSSFWorkbook(1000); //大于1000行时会把之前的行写入硬盘，解决内存溢出}String[] headerArr = headers.split(",");String[] includeArr = includes.split(",");//字体Font font = wb.createFont();   //font.setFontHeightInPoints((short)14);   //font.setColor(IndexedColors.DARK_BLUE.getIndex());   font.setBoldweight(Font.BOLDWEIGHT_BOLD);//样式CellStyle styleBOLD = createBorderedStyle(wb);styleBOLD.setFont(font);styleBOLD.setVerticalAlignment(CellStyle.VERTICAL_CENTER);styleBOLD.setWrapText(false); //自动换行//样式CellStyle styleWrap = createBorderedStyle(wb);styleWrap.setWrapText(false);styleWrap.setVerticalAlignment(CellStyle.VERTICAL_TOP);//表Sheet sheet = wb.createSheet(sheetName);//列宽//sheet.autoSizeColumn(( short ) 0 ); // 调整第一列宽度//sheet.SetColumnWidth(1, 50 * 256);  //设置列宽，50个字符宽度。宽度参数为1/256，故乘以256，中文的要再乘以2
//        sheet.setColumnWidth(0, 3000);//行Row row = sheet.createRow(0);//单元格Cell cell;//写入标题行for(int i=0; i<headerArr.length; i++){cell = row.createCell(i);cell.setCellValue(headerArr[i]);cell.setCellStyle(styleBOLD);}Map rowMap;          //行mapString fieldName; //字段名Object value;      //属性值DateFormat dtf = new SimpleDateFormat(dataPattern); //yyyy-MM-dd HH:mm:ssfor(int i=0; i<list.size(); i++){row = sheet.createRow(i+1);rowMap = list.get(i);for(int f=0,c=0; f<includeArr.length; f++){fieldName = includeArr[f];cell = row.createCell(c);cell.setCellStyle(styleWrap);value = rowMap.get(fieldName);        //得到此字段的值if(value==null){} else if (value instanceof Date){  cell.setCellValue(dtf.format((Date)value));} else {cell.setCellValue(value.toString());}c++;}}//写入文件FileOutputStream fOut = new FileOutputStream(filePath);wb.write(fOut);}/*** 导出excel* @param list             数据列表 List<List<Object>>，List<Object>是一行数据* @param headers         列标题，以英文逗号分割，必传* @param filePath          导出文件全路径* @param sheetName          sheet名称：sheet1* @param dataPattern      日期格式：yyyy-MM-dd HH:mm:ss* @throws Exception     另一个程序正在使用此文件，进程无法访问*/public static void exportListList(List<List<Object>> list, String headers, String filePath, String sheetName, String dataPattern) throws Exception{//工作簿Workbook wb;// 创建模板工作表if (filePath.endsWith(".xls")) {wb = new HSSFWorkbook();} else {//templatewb = new XSSFWorkbook(new FileInputStream(filePath));//wb = new XSSFWorkbook();wb = new SXSSFWorkbook(1000); //大于1000行时会把之前的行写入硬盘，解决内存溢出}String[] headerArr = headers.split(",");//字体Font font = wb.createFont();   //font.setFontHeightInPoints((short)14);   //font.setColor(IndexedColors.DARK_BLUE.getIndex());   font.setBoldweight(Font.BOLDWEIGHT_BOLD);//样式CellStyle styleBOLD = createBorderedStyle(wb);styleBOLD.setFont(font);styleBOLD.setVerticalAlignment(CellStyle.VERTICAL_CENTER);styleBOLD.setWrapText(false); //自动换行//样式CellStyle styleWrap = createBorderedStyle(wb);styleWrap.setWrapText(false);styleWrap.setVerticalAlignment(CellStyle.VERTICAL_TOP);//表Sheet sheet = wb.createSheet(sheetName);//列宽//sheet.autoSizeColumn(( short ) 0 ); // 调整第一列宽度//sheet.SetColumnWidth(1, 50 * 256);  //设置列宽，50个字符宽度。宽度参数为1/256，故乘以256，中文的要再乘以2
//        sheet.setColumnWidth(0, 3000);//行Row row = sheet.createRow(0);//单元格Cell cell;//写入标题行for(int i=0; i<headerArr.length; i++){cell = row.createCell(i);cell.setCellValue(headerArr[i]);cell.setCellStyle(styleBOLD);}List<Object> dataRow;Object value; //属性值DateFormat dtf = new SimpleDateFormat(dataPattern); //yyyy-MM-dd HH:mm:ssfor(int i=0; i<list.size(); i++){dataRow = list.get(i);row = sheet.createRow(i+1);for(int j=0; j<dataRow.size(); j++){cell = row.createCell(j);cell.setCellStyle(styleWrap);//cell.setCellType(Cell.CELL_TYPE_STRING);value = dataRow.get(j);if(value==null){} else if (value instanceof Date){  cell.setCellValue(dtf.format((Date)value));} else {cell.setCellValue(value.toString());}}}//写入文件FileOutputStream fOut = new FileOutputStream(filePath);wb.write(fOut);}private static CellStyle createBorderedStyle(Workbook wb){   CellStyle style = wb.createCellStyle();   style.setBorderRight(CellStyle.BORDER_THIN);   style.setRightBorderColor(IndexedColors.BLACK.getIndex());   style.setBorderBottom(CellStyle.BORDER_THIN);   style.setBottomBorderColor(IndexedColors.BLACK.getIndex());   style.setBorderLeft(CellStyle.BORDER_THIN);   style.setLeftBorderColor(IndexedColors.BLACK.getIndex());   style.setBorderTop(CellStyle.BORDER_THIN);   style.setTopBorderColor(IndexedColors.BLACK.getIndex());   return style;   }
}

得到单元格的字符串内容，注意：有的excel里有隐藏列

import java.text.DecimalFormat;

import java.text.SimpleDateFormat;

import org.apache.poi.ss.usermodel.Cell;

import org.apache.poi.ss.usermodel.DateUtil;

// 得到单元格的字符串内容public static String getCellValue(Cell cell) {DecimalFormat df = new DecimalFormat("#");if (cell == null)return "";switch (cell.getCellType()) {case Cell.CELL_TYPE_NUMERIC:if (DateUtil.isCellDateFormatted(cell)) {SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");return sdf.format(cell.getDateCellValue()).toString();// return sdf.format(DateUtil.getJavaDate(cell.getNumericCellValue())).toString();}return df.format(cell.getNumericCellValue());case Cell.CELL_TYPE_STRING:// System.out.println(cell.getStringCellValue());return cell.getStringCellValue();case Cell.CELL_TYPE_FORMULA:return cell.getCellFormula();case Cell.CELL_TYPE_BLANK:return "";case Cell.CELL_TYPE_BOOLEAN:return cell.getBooleanCellValue() + "";case Cell.CELL_TYPE_ERROR:return cell.getErrorCellValue() + "";}return "";}

下载片段：

//下载try {fileName= new String(fileName.getBytes("GBK"), "ISO-8859-1");} catch (UnsupportedEncodingException e) {e.printStackTrace();}response.setContentType("application/octet-stream"); //MIME类型//该步是最关键的一步，使用setHeader()方法弹出"是否要保存"的对话框，打引号的部分都是固定的值，不要改变   response.setHeader("Content-disposition","attachment;filename="+fileName);//写入文件wb.write(response.getOutputStream());

参考：

http://www.iteye.com/problems/65838