servlet提取冗余代码，通过反射完成方法分配，

package com.zky.hotelmanagement.web.servlet;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.poi.hssf.usermodel.*;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.List;

public class BaseServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //完成方法分发
        //1.获取请求路径
        String uri = request.getRequestURI();
        System.out.println("请求uri:"+uri);
        //2.获取方法名
        String methodName = uri.substring(uri.lastIndexOf('/') + 1);
        System.out.println("方法名称:"+methodName);
        request.setCharacterEncoding("utf-8");

        //3.获取方法对象Method
        try {
            Method method = this.getClass().getMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);
            //4.执行方法
            method.invoke(this,request,response);

        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }

    public void writerValue(HttpServletResponse response,Object obj) throws IOException {
        response.setContentType("application/json;charset=utf-8");
        ObjectMapper mapper = new ObjectMapper();
        mapper.writeValue(response.getOutputStream(),obj);
    }

    public void writeValueAsString(HttpServletResponse response,Object obj) throws IOException {
        response.setContentType("application/json;charset=utf-8");
        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(obj);
        response.getWriter().write(json);
    }

    /**
     * 生成Excel表
     * @param response
     * @param dataList 表格数据
     * List<String[]> dataList = new ArrayList<>();
     *         List<Map<String, Object>> results = service.findAll();
     *         for (Map<String, Object> result : results) {
     *             System.out.println(result);
     *             String[] data = new String[header.length];
     *
     *             for (int i = 0; i < header.length; i++) {
     *                 if (result.get(header[i]) != null)
     *                  //一行中所有单元格数据
     *                     data[i] = result.get(header[i]).toString();
     *             }
     *             dataList.add(data);
     *
     *         }
     * @param header 表头
     * @param name 表名
     * @throws IOException
     */
    public void writeToExcel(HttpServletResponse response, List<String[]> dataList, String[] header,String name) throws IOException{

        //声明一个工作簿
        HSSFWorkbook workbook = new HSSFWorkbook();
        HSSFCellStyle style = workbook.createCellStyle();

        //生成一个表格，设置表格名称为"UserData"
        HSSFSheet sheet = workbook.createSheet(name);

        //设置表格列宽度为10个字节
        sheet.setDefaultColumnWidth(10);

        //创建第一行表头
        HSSFRow headrow = sheet.createRow(0);

//        遍历添加表头
        for (int i = 0; i < header.length; i++) {
            //创建一个单元格

            HSSFCell cell = headrow.createCell(i);

            //创建一个内容对象
            HSSFRichTextString text = new HSSFRichTextString(header[i]);

            //将内容对象的文字内容写入到单元格中
            cell.setCellValue(text);
        }

        //模拟遍历结果集，把内容加入表格
        int temp = 1;
        for (String[] data : dataList) {
            HSSFRow row = sheet.createRow(temp++);
            for (int i = 0; i < data.length; i++) {
                HSSFCell cell = row.createCell(i);
                HSSFRichTextString text = new HSSFRichTextString(data[i]);
                cell.setCellValue(text);
            }

        }


        //准备将Excel的输出流通过response输出到页面下载
        //八进制输出流
        response.setContentType("application/octet-stream");

        //这后面可以设置导出Excel的名称，此例中名为userData.xls
        response.setHeader("Content-disposition", "attachment;filename="+name+".xls");

        //刷新缓冲
        response.flushBuffer();

        //workbook将Excel写入到response的输出流中，供页面下载
        workbook.write(response.getOutputStream());
    }

}