工具类--Excel 导出poi

实现功能 --批量导出excel 文件，配置一个sheet多少条数据，根据查询数据量的多少确定生成几个sheet页。

pom 文件导入ExcelUtils工具包，依赖于poi包。

<!-- https://mvnrepository.com/artifact/org.hellojavaer/poi-excel-utils -->
<dependency>
    <groupId>org.hellojavaer</groupId>
    <artifactId>poi-excel-utils</artifactId>
    <version>1.1.0-beta</version>
</dependency>

找到ExcelUtils工具包，重构代码。

package cn.enn.chaoscloud.master.utils;

import com.lkx.util.StringUtil;
import lombok.extern.slf4j.Slf4j;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.DateUtil;
import org.springframework.beans.BeanUtils;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Serializable;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

@Slf4j
public class ExcelUtils implements Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * getMap:(将传进来的表头和表头对应的属性存进Map集合，表头字段为key,属性为value)
     *
     * @author likaixuan
     * @param
     *            : String keyValue = "手机名称:phoneName,颜色:color,售价:price";
     * @return
     * @since JDK 1.7
     */
    public static Map<String, String> getMap(String keyValue) {
        Map<String, String> map = new HashMap<String, String>();
        if (keyValue != null) {
            String[] str = keyValue.split(",");
            for (String element : str) {
                String[] str2 = element.split(":");
                map.put(str2[0], str2[1]);
            }
        }
        return map;
    }

    /**
     * @author likaixuan
     * @param
     * @return List
     * @Date 2018年5月9日 21:42:24
     * @since JDK 1.7
     */
    public static List<String> getList(String keyValue) {
        List<String> list = new ArrayList<String>();
        if (keyValue != null) {
            String[] str = keyValue.split(",");

            for (String element : str) {
                String[] str2 = element.split(":");
                list.add(str2[0]);
            }
        }
        return list;
    }

    /**
     * setter:(反射的set方法给属性赋值)
     *
     * @author likaixuan
     * @param obj
     *            具体的类
     * @param att
     *            类的属性
     * @param value
     *            赋予属性的值
     * @param type
     *            属性是哪种类型 比如:String double boolean等类型
     * @throws Exception
     * @since JDK 1.7
     */
    public static void setter(Object obj, String att, Object value, Class<?> type, int row, int col, Object key)
            throws Exception {
        try {
            Method method = obj.getClass().getMethod("set" + StringUtil.toUpperCaseFirstOne(att), type);
            method.invoke(obj, value);
        } catch (Exception e) {
            throw new Exception("第" + (row + 1) + " 行  " + (col + 1) + "列   属性：" + key + " 赋值异常  " + e);
        }

    }

    /**
     * getAttrVal:(反射的get方法得到属性值)
     *
     * @author likaixuan
     * @param obj
     *            具体的类
     * @param att
     *            类的属性
     * @param
     *
     * @param type
     *            属性是哪种类型 比如:String double boolean等类型
     * @throws Exception
     * @since JDK 1.7
     */
    public static Object getAttrVal(Object obj, String att, Class<?> type) throws Exception {
        try {
            Method method = obj.getClass().getMethod("get" + StringUtil.toUpperCaseFirstOne(att));
            Object value = new Object();
            value = method.invoke(obj);
            return value;
        } catch (Exception e) {
            log.error(e.getMessage(), e);
            return null;
        }

    }

    /**
     * getValue:(得到Excel列的值)
     *
     * @author likaixuan
     * @param
     * @return
     * @throws Exception
     * @since JDK 1.7
     */
    public static void getValue(Cell cell, Object obj, String attr, Class attrType, int row, int col, Object key)
            throws Exception {
        Object val = null;
        if (cell.getCellType() == Cell.CELL_TYPE_BOOLEAN) {
            val = cell.getBooleanCellValue();

        } else if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {
            if (DateUtil.isCellDateFormatted(cell)) {
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                try {
                    if (attrType == String.class) {
                        val = sdf.format(DateUtil.getJavaDate(cell.getNumericCellValue()));
                    } else {
                        val = dateConvertFormat(sdf.format(DateUtil.getJavaDate(cell.getNumericCellValue())));
                    }
                } catch (ParseException e) {
                    throw new Exception("第" + (row + 1) + " 行  " + (col + 1) + "列   属性：" + key + " 日期格式转换错误  ");
                }
            } else {
                if (attrType == String.class) {
                    cell.setCellType(Cell.CELL_TYPE_STRING);
                    val = cell.getStringCellValue();
                } else if (attrType == BigDecimal.class) {
                    val = new BigDecimal(cell.getNumericCellValue());
                } else if (attrType == long.class) {
                    val = (long) cell.getNumericCellValue();
                } else if (attrType == Double.class) {
                    val = cell.getNumericCellValue();
                } else if (attrType == Float.class) {
                    val = (float) cell.getNumericCellValue();
                } else if (attrType == int.class || attrType == Integer.class) {
                    val = (int) cell.getNumericCellValue();
                } else if (attrType == Short.class) {
                    val = (short) cell.getNumericCellValue();
                } else {
                    val = cell.getNumericCellValue();
                }
            }

        } else if (cell.getCellType() == Cell.CELL_TYPE_STRING) {
            val = cell.getStringCellValue();
        }

        setter(obj, attr, val, attrType, row, col, key);
    }

    /**
     * exportExcel:(导出Excel)
     *
     * @author likaixuan
     * @param
     * @return
     * @throws Exception
     * @since JDK 1.7
     */
    public static void exportExcel(HSSFWorkbook wb,OutputStream outputStream, String keyValue, List<?> list, String classPath,int sheetNum,int pageNum)
            throws Exception {

        Map<String, String> map = getMap(keyValue);
        List<String> keyList = getList(keyValue);

        Class<?> demo = null;
        demo = Class.forName(classPath);
        Object obj = demo.newInstance();

        // 建立新的sheet对象（excel的表单）
        String sheetName = "sheet"+String.valueOf(sheetNum);
        HSSFSheet sheet = wb.createSheet(sheetName);
        // 声明样式
        HSSFCellStyle style = wb.createCellStyle();
        // 居中显示
        style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
        // 在sheet里创建第一行为表头，参数为行索引(excel的行)，可以是0～65535之间的任何一个
        HSSFRow rowHeader = sheet.createRow(0);
        // 创建单元格并设置单元格内容

        // 存储属性信息
        Map<String, String> attMap = new HashMap();
        int index = 0;

        for (String key : keyList) {
            rowHeader.createCell(index).setCellValue(key);
            attMap.put(Integer.toString(index), map.get(key).toString());
            index++;
        }

        // 在sheet里创建表头下的数据
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
            HSSFRow row = sheet.createRow(i + 1);
            for (int j = 0; j < map.size(); j++) {

                Class<?> attrType = BeanUtils.findPropertyType(attMap.get(Integer.toString(j)),
                        new Class[] { obj.getClass() });

                Object value = getAttrVal(list.get(i), attMap.get(Integer.toString(j)), attrType);
                if (null == value) {
                    value = "";
                }
                row.createCell(j).setCellValue(value.toString());
                style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
            }
        }
        // 输出Excel文件
        try {
            if(sheetNum == pageNum || pageNum == 0){
                wb.write(outputStream);
                outputStream.close();
            }
        } catch (FileNotFoundException e) {
            throw new FileNotFoundException("导出失败！" + e);
        } catch (IOException e) {
            throw new IOException("导出失败！" + e);
        }

    }

    /**
     * String类型日期转为Date类型
     *
     * @param dateStr
     * @return
     * @throws ParseException
     * @throws Exception
     */
    public static Date dateConvertFormat(String dateStr) throws ParseException {
        Date date = new Date();
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        date = format.parse(dateStr);
        return date;
    }
}

调用封装工具类

public static final int page_size = 10000;

@PostMapping("queryUnusedGasListExcel")
public byte[] queryUnusedGasListExcel(@RequestBody UnusedGasDTO unusedGasDTO) throws Exception{
    byte[] bytes = null;
    try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream()){
        int list_count  = unusedGasService.findCountList(unusedGasDTO);
        // 根据行数求数据提取次数
        int export_times = list_count % page_size > 0 ? list_count / page_size
                + 1 : list_count / page_size;

        // 创建HSSFWorkbook对象(excel的文档对象)
        HSSFWorkbook wb = new HSSFWorkbook();
        for (int j = 0; j < export_times; j++) {
            unusedGasDTO.setPositionNum(j*page_size);
            unusedGasDTO.setShowNum(page_size);
            List<UnusedGasVO> list = unusedGasService.downLoadByList(unusedGasDTO);
            int len = list.size() < page_size ? list.size() : page_size;
            String keyValue = "客户名称:customerName,房产名称:houseName,表钢号:meterCode,余额(元):balance,表底数:meterBase,未用气天数:unusedGasDays,客户类型编码:customerCode,联系方式:customerTel,表型名称:metersTypeName,合约号:contractNum," +
                    "集团id:groupId,集团编码:groupName,公司id:companyId,公司编码:companyCode,公司名称:companyName," +
                    "客户电话:customerTel,房产编码:houseCode,表型编码:meterType,未用气天数时间:unusedGasTime";
            //HSSFWorkbook ;j+1 sheet当前页; export_times sheet总页数
            /**
             * HSSFWorkbook
             * outputStream流
             * 根据反射获取实体类，并且赋值
             * list 查询到的实体集合
             * classPath list 中实体的路径，反射用到
             * j+1 要写入sheet的页数
             * 重新查询数据的次数
             */
            ExcelUtils.exportExcel(wb,byteArrayOutputStream, keyValue, list, "cn.enn.chaoscloud.domain.archives.meter.vo.UnusedGasVO", j+1,export_times);
        }
        bytes = byteArrayOutputStream.toByteArray();

    }catch (Exception e){
        log.error(e.getMessage(), e);
    }
    return bytes;
}