struts2将数据库中的数据导出到excel和csv中

1.该方法是通过poi的包导出的（如果是导出到csv则不需要引入jar包）

需要进入的jar包：

<dependency>
   <groupId>org.apache.commons</groupId>
   <artifactId>commons-collections4</artifactId>
   <version>4.1</version>
</dependency>
<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>

2.struts.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
   "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
   "http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
   <package name="dataQueryPackage" extends="loginPackage">
      <action name="dataQuery_*" class="com.hx.pay.web.cms.action.DataQueryAction" method="{1}">
         <result name="downLoadData" type="stream">
            <param name="inputName">fileInputStream</param>
            <param name="contentType">application/vnd.ms-excel;charset=utf-8</param>
            <param name="contentDisposition">attachment;filename="${fileName}.xlsx"</param>
            <param name="bufferSize">2048</param>
         </result>
      </action>
   </package>
</struts>

3.页面（有两种写法）

第一种方法：

下载数据的form：

<form id="downLoadForm" method="post">
    <button type="button" id="downLoadTradeData">导出数据</button>
</form>

JQuery:

$(function () {
    $('#downLoadTradeData').click(function () {
        document.getElementById("downLoadForm").action="tradeQuery_downLoadData.action";
        document.getElementById("downLoadForm").submit();
    })
})

第二种方法：

下载数据的button:

<button onclick="downLoadData()">导出数据</button>

 javascript:

function downLoadData() {
    try {
        var url = "fourElementQuery_downLoadData.action";
        var elemIF = document.createElement("iframe");
        elemIF.src = url;
        elemIF.style.display = "none";
        document.body.appendChild(elemIF);
    } catch (e) {}
}

4.Controller

导出到excel

package com.hx.pay.web.cms.action;

import com.hx.pay.common.page.PageParam;
import com.hx.pay.common.utils.BeanUtils;
import com.hx.pay.web.boss.util.DateUtil;
import com.hx.pay.web.boss.util.DictUtil;
import com.hx.pay.web.boss.util.Path;
import com.hx.pay.web.cms.biz.TradeQueryBiz;
import com.hx.pay.web.cms.entity.PayReqOrderQueryRequestVOT;
import com.hx.pay.web.permission.base.PermissionBaseAction;
import com.yooli.pay.gateway.facade.dto.charge.PayReqOrderQueryDTO;
import com.yooli.pay.gateway.facade.dto.charge.PayReqOrderQueryRequestVO;
import com.yooli.pay.gateway.facade.dto.page.PageVO;
import org.apache.commons.lang.StringUtils;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;

import java.io.*;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.SimpleDateFormat;
import java.util.*;

public class TradeQueryAction extends PermissionBaseAction {
    private InputStream fileInputStream;
    private String fileName;
   
    /**
     * 数据下载
     * @return
     */
    public String downLoadData() {
        List<Object> datas = getDatas();    //这一步获取数据
        exportToExcel(datas);
        return "downLoadData";
    }

    private void exportToExcel(List<Object> datas) {
        //内存中只创建100个对象，写临时文件，当超过100条，就将内存中不用的对象释放
        SXSSFWorkbook wb = new SXSSFWorkbook(100);

        //生成excel表格
        createExcel(wb, datas);

        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddhhmmss"); 
        fileName = "datas-"+sdf.format(new Date());
        //设置字符，防止乱码
        fileName = new String(fileName.getBytes("UTF-8"), "ISO8859-1");
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        wb.write(outputStream);
        byte[] ba = outputStream.toByteArray();
        fileInputStream = new ByteArrayInputStream(ba);
        outputStream.flush();
        outputStream.close();
    }


    private void createExcel(SXSSFWorkbook wb, List<Object> datas) {
        if (datas!= null && !datas.isEmpty()) {
            Sheet sheet = wb.createSheet("datas" + (wb.getNumberOfSheets()+1));  //创建工作表,如果是多个sheet的话，sheet名字依次是datas1、datas2、datas3...
            Row nRow = sheet.createRow(0);
            //定义表头
            createExcelHead(nRow);  //创建表头
           
            int excelColumnsCount = sheet.getLastRowNum();  //获取最后一行的行号
            Cell nCell = null; //列对象
            for (int i = 0; i < datas.size(); i ++) {
                Object o = datas.get(i);
                excelColumnsCount ++;
                nRow = sheet.createRow(excelColumnsCount);  //循环创建行
                //填充表格内容
                setExcelContent(nCell, nRow, o);
            }
            datas.clear();    //创建表完以后将list清空，便于垃圾回收
        }
    }

    private void setExcelContent(Cell nCell, Row nRow, Object p) {
        nCell = nRow.createCell(0);
        nCell.setCellValue(p.getPayStatusF());

        nCell = nRow.createCell(1);
        nCell.setCellValue(p.getPayNo());

        nCell = nRow.createCell(2);
        nCell.setCellValue(p.getOutTradeNo());

        nCell = nRow.createCell(3);
        nCell.setCellValue(p.getChannelCode());
    }

    private void  createExcelHead(Row nRow) {
        Cell cel0 = nRow.createCell(0);
        cel0.setCellValue("第一列");

        Cell cel2 = nRow.createCell(1);
        cel2.setCellValue("第二列");

        Cell cel3 = nRow.createCell(2);
        cel3.setCellValue("第三列");

        Cell cel4 = nRow.createCell(3);
        cel4.setCellValue("第四列");
    }

    public String getFileName() {
        return fileName;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

    public InputStream getFileInputStream() {
        return fileInputStream;
    }

    public void setFileInputStream(InputStream fileInputStream) {
        this.fileInputStream = fileInputStream;
    }
}

 导出到csv

private void exportToCsv(List<Object> datas, HttpServletResponse response) {
        if (datas!= null && !datas.isEmpty()) {
            StringBuilder sBuilder = new StringBuilder();
            sBuilder.append("第一列,第二列,第三列,第四列\n");
            createCsvContent(sBuilder, datas);

            try {
                SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddhhmmss");
                String fileName = "datas-"+sdf.format(new Date()) + ".csv";
                response.setHeader("content-disposition", "attachment;filename=" + fileName);
                OutputStream out = response.getOutputStream();
                out.write(sBuilder.toString().getBytes(Charset.forName("GBK")));
            } catch (IOException e) {
                logger.info("exportToCsv#生成csv文件异常#", e);
            }
        }
    }

    private void createCsvContent(StringBuilder sBuilder, List<Object> datas) {
        if (datas!= null && !datas.isEmpty()) {
            for (PayReqOrderQueryDTO p : voList) {
                sBuilder.append(p.getPayStatusF()).append(",")
                        .append(p.getPayNo() + "\t").append(",")    //如果内容是数字类型的字符串，则要加"\t"，否则会出现科学计数法，导致不准确
                        .append(p.getOutTradeNo() + "\t").append(",")
                        .append(p.getChannelCode()).append(",")
                        .append("\n");
            }
            datas.clear();
            logger.info("createCsvContent#生成csv文件结束");
        } else {
            logger.info("createCsvContent#数据为空#voLise:{}", datas);
        }
    }