导出CSV

导出CSV

Util代码:

package com.mmall.util;

import lombok.extern.slf4j.Slf4j;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.List;
import java.util.Map;

/**
 * 导出CSV 工具类
 * @date 2019/5/6
 */
@Slf4j
public class CSVUtil {
    /**
     * CSV文件列分隔符
     */
    private static final String CSV_COLUMN_SEPARATOR = ",";

    /**
     * CSV文件列分隔符
     */
    private static final String CSV_RN = "\r\n";

    /**
     * 数据初始化
     *
     * @param data            数据库查出来的数据
     * @param displayColNames csv表头
     * @param matchColNames   data中的key ，可以说是数据库字段了,原本为”0001”类型的数据在excel中打开会被默认改变为”1”的数据。 解决方法 :key前加"'"用于特殊处理；
     *                        例如 输入列名为"num"数字为 001，则传入的key值为"-num",保证输出为字符串
     * @return
     */
    public static String formatCsvData(List<Map<String, Object>> data,
                                       String displayColNames, String matchColNames) {

        StringBuilder builder = new StringBuilder();

        String[] displayColNamesArr;
        String[] matchColNamesMapArr;

        displayColNamesArr = displayColNames.split(",");
        matchColNamesMapArr = matchColNames.split(",");

        // 输出列头
        for (String s : displayColNamesArr) {
            builder.append(s).append(CSV_COLUMN_SEPARATOR);
        }
        builder.append(CSV_RN);

        if (null != data) {
            // 输出数据
            for (Map<String, Object> datum : data) {

                for (String s : matchColNamesMapArr) {
                    //处理list<Map>中 value=null的数据
                    Object object = datum.get(s);
                    if (object == null) {
                        object = datum.get(s.substring(1));
                    }
                    if (object == null) {
                        builder.append(CSV_COLUMN_SEPARATOR);
                    } else {
                        if (s.startsWith("-")) {
                            builder.append("\t").append(object.toString()).append(CSV_COLUMN_SEPARATOR);
                        } else {
                            builder.append(object).append(CSV_COLUMN_SEPARATOR);
                        }
                    }
                }
                builder.append(CSV_RN);
            }
        }
        log.info("csv file Initialize successfully");
        return builder.toString();
    }

    /**
     * 导出
     *
     * @param fileName 文件名
     * @param content  内容
     * @param request
     * @param response
     * @throws IOException
     */
    public static void exportCsv(String fileName, String content, HttpServletRequest request,
                                 HttpServletResponse response) throws IOException {

        // 读取字符编码
        String csvEncoding = StandardCharsets.UTF_8.toString();

        // 设置响应
        response.setCharacterEncoding(csvEncoding);
        response.setContentType("text/csv; charset=" + csvEncoding);
        response.setHeader("Pragma", "public");
        response.setHeader("Cache-Control", "max-age=30");

        fileName = URLEncoder.encode(fileName, csvEncoding);
        response.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");

        // 写出响应
        OutputStream os = response.getOutputStream();
        os.write(content.getBytes(csvEncoding));
        os.flush();
        os.close();
        log.info("csv file download completed");
    }
}

代码:

public void exportSeq(HttpServletResponse response) throws IOException {
    List<SeqNoVo> seqNoVos = (List<SeqNoVo>) session.getAttribute("seqNoVos");
    List<Map<String, Object>> data = seqNoVos.stream().map(seqNoVo -> {
        Map<String, Object> map = new HashMap<>(16);
        map.put("id", seqNoVo.getId());
        map.put("seq_no", seqNoVo.getSeqNo());
        map.put("integral", seqNoVo.getIntegral());
        map.put("status", seqNoVo.getStatus().equals(0) ? "否" : "是");
        map.put("remarks", seqNoVo.getRemarks());
        return map;
    }).collect(Collectors.toList());

    //csv表头
    String header = "序号,序列号,对应积分,是否被使用,备注";
    //对应的数据库字段
    String key = "id,seq_no,integral,status,remarks";
    //csv文件名
    String fileName = "序列号.csv";

    String content = CSVUtil.formatCsvData(data, header, key);

    CSVUtil.exportCsv(fileName, content, request, response);
    log.info("导出完成");
}

HTML:

<div class="hidden-xs" id="SeqnoTableToolbar" role="group">
   <#button name="生成领奖码" icon="fa-plus" clickFun="Seqno.openAddSeqno()"/>
    <a class="btn btn-primary button-margin" id="updown" onclick="updown()">
        <i class="fa "></i>&nbsp;导出CSV
    </a>
</div>

<script>
    function updown() {
    	// 下载链接需要添加当前时间戳 以防浏览器缓存导致下载内容不一致
        $("#updown").attr("href",Feng.ctxPath + "/seqno/exportSeq?curr="+new Date().getTime());
    }
</script>