本文主要是个人工作上的一个记录，技术有限，可能没有那么全面，见谅！

背景

项目中用的jxls版本是1.0以下的，导出2万多条数据都慢到不行，提出了2种方案，一种是升级jxls的版本，一种是使用poi导出，因为已经开发好的功能，根据模板生成的excel，所以在原有的基础上升级了2.4，只需要修改一些语法，工作量稍微少一点。

代码

pom.xml

<!-- 生成和读入Excel工具类 -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.17</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.17</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml-schemas</artifactId>
            <version>3.17</version>
        </dependency>
        <dependency>
            <groupId>org.jxls</groupId>
            <artifactId>jxls</artifactId>
            <version>2.4.4</version>
        </dependency>
        <dependency>
            <groupId>org.jxls</groupId>
            <artifactId>jxls-poi</artifactId>
            <version>1.0.14</version>
        </dependency>

JxlsExcelView，公司使用的工具类

package com.XXX.common.utils;

import org.springframework.web.servlet.view.AbstractView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Map;

public class JxlsExcelView extends AbstractView {  
      
    private static final String CONTENT_TYPE = "application/vnd.ms-excel";  
  
    private String templatePath;  
  
    private String exportFileName;  
  
    /** 
     * @param templatePath 模版相对于当前classpath路径 
     * @param exportFileName 导出文件名 
     */  
    public JxlsExcelView(String templatePath, String exportFileName) {  
        this.templatePath = templatePath;  
        this.exportFileName = exportFileName;  
        setContentType(CONTENT_TYPE);  
    }  
  
    @Override  
    protected void renderMergedOutputModel(Map<String, Object> model, HttpServletRequest request,  
            HttpServletResponse response) throws Exception {  
          
        InputStream is = null;
        OutputStream os = null;  
          
        os = response.getOutputStream();  
        response.setContentType(getContentType());  
          
        // 解决导出文件名中文乱码  
        String filename = new String(exportFileName.getBytes("gb2312"), "iso8859-1");  
        response.setHeader("content-disposition", "attachment;filename=" + filename + ".xls");  
          
        String webInfPath = request.getSession().getServletContext().getRealPath("/WEB-INF/");
         // 获取excel模板  
        is = new FileInputStream(new File(webInfPath + "/template/" + templatePath));  

        //转换成excel并输出 ~~这是以前1.0之前的写法
//        XLSTransformer transformer = new XLSTransformer();
//        Workbook workbook = transformer.transformXLS(is, model);
       JxlsUtils.exportExcel(is,os,model);
        //将内容写入输出流并把缓存的内容全部发出去    
//        workbook.write(os);
        os.flush();  
        os.close();  
        is.close();  
    }  
}  

JxlsUtils 这是参考其他大神使用的一个工具类

package com.XXX.common.utils;

import org.jxls.common.Context;
import org.jxls.expression.JexlExpressionEvaluator;
import org.jxls.transform.Transformer;
import org.jxls.transform.poi.PoiTransformer;
import org.jxls.util.JxlsHelper;

import java.io.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**
 * jxls2.4 导出excle工具类
 * @SINCE 2018/10/9 17:06
 * @AUTHOR LCM
 * @Param
 * @return
 */
public class JxlsUtils{
    
    public static void exportExcel(InputStream is, OutputStream os, Map<String, Object> model) throws IOException{
        Context context = PoiTransformer.createInitialContext();
        if (model != null) {
            for (String key : model.keySet()) {
                context.putVar(key, model.get(key));
            }
        }
        JxlsHelper jxlsHelper = JxlsHelper.getInstance();
        Transformer transformer  = jxlsHelper.createTransformer(is, os);
        //获得配置
        JexlExpressionEvaluator evaluator = (JexlExpressionEvaluator)transformer.getTransformationConfig().getExpressionEvaluator();
        //设置静默模式，不报警告
//        evaluator.getJexlEngine().setSilent(true);
        //函数强制，自定义功能
        Map<String, Object> funcs = new HashMap<String, Object>();
        funcs.put("utils", new JxlsUtils());    //添加自定义功能
        evaluator.getJexlEngine().setFunctions(funcs);
        //必须要这个，否者表格函数统计会错乱
        jxlsHelper.setUseFastFormulaProcessor(false).processTemplate(context, transformer);
    }

    public static void exportExcel(File xls, File out, Map<String, Object> model) throws FileNotFoundException, IOException {
            exportExcel(new FileInputStream(xls), new FileOutputStream(out), model);
    }
    
    public static void exportExcel(String templatePath, OutputStream os, Map<String, Object> model) throws Exception {
        File template = getTemplate(templatePath);
        if(template != null){
            exportExcel(new FileInputStream(template), os, model);    
        } else {
            throw new Exception("Excel 模板未找到。");
        }
    }
    
    //获取jxls模版文件
    public static File getTemplate(String path){
        File template = new File(path);
        if(template.exists()){
            return template;
        }
        return null;
    }    
}

controller导出调用的语法了。

    /**
     * 按照日期 导出excel
     *
     * @param producUnitDoc
     * @param page
     * @param rows
     * @return
     */
    @RequestMapping(value = "/exportFunctionExcel")
    public ModelAndView exportFunctionExcel(MealOrder mealOrder) {
        ModelAndView mv = new ModelAndView();
        Map<String, Object> dataMap = mealOrderApi.export(mealOrder);
        List<Map<String, String>> varList = (List<Map<String, String>>) dataMap.get("varList");
        if(varList!=null&&varList.size()>0) {
            try {
                return new ModelAndView(new JxlsExcelView("mealOrder.xls", (String) dataMap.get("excelName")), dataMap);
            } catch (Exception e) {
            }
        }
        return mv;
    }

接口的参数格式，这里我们使用list导出

@Override
    public Map<String, Object> export(MealOrder mealOrder) {
        Map<String, Object> dataMap = new HashMap<String, Object>();


/*      // 定义，设置excel头部
        List<String> titles = new ArrayList<String>();
        titles.add("使用状态(1启用 0禁用)*");
        dataMap.put("titles", titles);*/
        // 定义，设置excel数据列表
        List<Map<String, String>> varList = new ArrayList<Map<String, String>>();
        List<MealOrder> list = dao.getAllList(mealOrder);
        for (MealOrder mealOrder1 : list) {
            dataMap.put("excelName", mealOrder.getExcelName());
            if (mealOrder1 != null && mealOrder1.getUuid() != null) {
                Map<String, String> vpd = new HashMap<String, String>();
                vpd.put("var1", mealOrder1.getTakeCode()); 
                vpd.put("var2", mealOrder1.getFoodNames());
                vpd.put("var3", String.valueOf(mealOrder1.getMealNumber())); 
                vpd.put("var4", mealOrder1.getApplyCompany()); 
                varList.add(vpd);
            }
        }
        dataMap.put("varList", varList);
        return dataMap;
    }