1.导出文件的工具类

package com.sszt.demo.util;

import java.io.BufferedOutputStream;
import java.text.MessageFormat;
import java.util.Calendar;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 导出文件文件的工具类
 */
public class ExportTextUtil {
        /**
         * 声明日志记录器
         */
        private static final Logger LOGGER = LoggerFactory.getLogger(ExportTextUtil.class);

        /**
         * 导出文本文件
         * @param response
         * @param jsonString
         * @param fileName
         */
        public static void writeToTxt(HttpServletResponse response,String jsonString,String fileName) {//设置响应的字符集
            response.setCharacterEncoding("utf-8");
            //设置响应内容的类型
            response.setContentType("text/plain");
            //设置文件的名称和格式
            response.addHeader(
                    "Content-Disposition",
                    "attachment; filename="
                            + FileUtil.genAttachmentFileName(fileName+ "_", "JSON_FOR_UCC_")
                            + MessageFormat.format("{0,date,yyyy-MM-dd HH:mm:ss}", new Object[]{Calendar.getInstance().getTime()})
                            + ".txt");//通过后缀可以下载不同的文件格式
            BufferedOutputStream buff = null;
            ServletOutputStream outStr = null;
            try {
                outStr = response.getOutputStream();
                buff = new BufferedOutputStream(outStr);
                buff.write(delNull(jsonString).getBytes("UTF-8"));
                buff.flush();
                buff.close();
            } catch (Exception e) {
                LOGGER.error("导出文件文件出错，e:{}",e);
            } finally {try {
                    buff.close();
                    outStr.close();
                } catch (Exception e) {
                    LOGGER.error("关闭流对象出错 e:{}",e);
                }
            }
        }

        /**
         * 如果字符串对象为 null，则返回空字符串，否则返回去掉字符串前后空格的字符串
         * @param str
         * @return
         */
        public static String delNull(String str) {
                String returnStr="";
                if (StringUtils.isNotBlank(str)) {
                    returnStr=str.trim();
                }
                return returnStr;
        }
}

package com.sszt.demo.util;

public abstract class FileUtil {
    
    /**
     * 生成导出附件中文名。应对导出文件中文乱码
     * <p>
     * response.addHeader("Content-Disposition", "attachment; filename=" + cnName);
     * 
     * @param cnName
     * @param defaultName
     * @return
     */
    public static String genAttachmentFileName(String cnName, String defaultName) {
        try {
//            fileName = URLEncoder.encode(fileName, "UTF-8");
            cnName = new String(cnName.getBytes("gb2312"), "ISO8859-1");
            /*
            if (fileName.length() > 150) {
                fileName = new String( fileName.getBytes("gb2312"), "ISO8859-1" );
            }
            */
        } catch (Exception e) {
            cnName = defaultName;
        }
        return cnName;
    }
}

2.在jsp页面添加一个按钮，点击触发以下事件

function exportTicket(id){
    window.open('back/sale/exportTicket/'+id, '_blank');
};

3.Controller层接收请求，调用service层获取数据，拼接文本内容，然后使用上面的工具响应页面以获得下载的文本文件

	@RequestMapping("/exportTicket/{orderId}")
	public void exportText(@PathVariable Integer orderId,  HttpServletResponse resp) {
		// 通过orderId查出对应的销售明细
		String text = saleService.list(orderId);
		// 将集合转换成字符串
		ExportTextUtil.writeToTxt(resp, text, "saleDetail");
	}

	public String list(Integer orderId) {
		String hql="FROM Sale WHERE o_id=?";
		List<Object> args=new ArrayList<>();
		args.add(orderId);
		// 通过orderId查出对应的销售明细
		List<Sale> list = saleDao.list(hql, args);
		//查询order信息
		SaleOrder order = orderDao.dtl(orderId);
		//拼接字符串，构成小票内容
		StringBuffer ticket = new StringBuffer();
		ticket.append("\t\t果农家园水果超市\r\n");
		ticket.append("店铺号:"+ order.getBaseOrgName()+"\t收银员:" + order.getSaler()+"\r\n");
		ticket.append("订单号:" + order.getId()+"\r\n");
		ticket.append("===================================\r\n");
		ticket.append("名称\t");
		ticket.append("单价\t");
		ticket.append("数量\t");
		ticket.append("总额\r\n");
		for (Sale sale : list) {
			ticket.append(sale.getFruitName() + "-" + sale.getFruitQuality()+"\t");
			ticket.append(sale.getPrice() + "\t\t");
			ticket.append(sale.getQuantity() + "\t\t");
			ticket.append(sale.getTotal() +"\r\n");
		}
		ticket.append("售出商品数:" + list.size() + "件\t");
		ticket.append("合计:" + order.getAmount() + "元\r\n");
		ticket.append("实收:" + order.getPay() + "元\t");
		ticket.append("找零:" + order.getChange() + "元\r\n");
		ticket.append("时间:" + Calendar.getInstance().getTime().toLocaleString()+"\r\n");
		ticket.append("===================================\r\n");
		ticket.append("\t\t天天平价,日日新鲜\r\n");
		ticket.append("钱票请当面点清，离开柜台恕不负责");
		return ticket.toString();
	}