ANTAI-WLTMS-API/src/main/java/com/steerinfo/dil/util/poiutil.java

package com.steerinfo.dil.util;


import com.baomidou.mybatisplus.core.toolkit.CollectionUtils;
import com.beust.jcommander.internal.Lists;
import com.google.common.collect.Maps;
import com.steerinfo.framework.utils.collection.MapUtils;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;



import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.lang.reflect.Method;
import java.nio.charset.StandardCharsets;

import java.util.*;


//导出excle工具类

public class poiutil {
    private final static String xls = "xls";
    private final static String xlsx = "xlsx";
    private final static String DATE_FORMAT = "yyyy/MM/dd";

    //参数说明:  fileName：文件名   projects：对象集合  columnNames： 列名   keys： map中的key
    public static void start_download(HttpServletResponse response, String fileName, List<?> projects, String[] columnNames, String[] keys) throws IOException {

        //将集合中对象的属性  对应到  List<Map<String,Object>>
        List<Map<String, Object>> list = createExcelRecord(projects, keys);

        ByteArrayOutputStream os = new ByteArrayOutputStream();
        try {
            //将转换成的Workbook对象通过流形式下载
            createWorkBook(list, keys, columnNames).write(os);
        } catch (IOException e) {
            e.printStackTrace();
        }
        byte[] content = os.toByteArray();
        InputStream is = new ByteArrayInputStream(content);
        // 设置response参数，可以打开下载页面
        response.reset();
        response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
        response.setCharacterEncoding("utf-8");
        response.setHeader("Content-Disposition", "attachment;filename=" + new String((fileName + ".xlsx").getBytes(), StandardCharsets.ISO_8859_1));
        ServletOutputStream out = response.getOutputStream();
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;
        try {
            bis = new BufferedInputStream(is);
            bos = new BufferedOutputStream(out);
            byte[] buff = new byte[2048];
            int bytesRead;
            while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
                bos.write(buff, 0, bytesRead);
            }
        } catch (final IOException e) {
            throw e;
        } finally {
            if (bis != null) bis.close();
            if (bos != null) bos.close();
        }
    }

    private static List<Map<String, Object>> createExcelRecord(List<?> projects, String[] keys) {
        List<Map<String, Object>> listmap = new ArrayList<Map<String, Object>>();
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("sheetName", "sheet");
        listmap.add(map);
        Object project = null;
        for (int j = 0; j < projects.size(); j++) {
            project = projects.get(j);
            Map<String, Object> mapValue = new HashMap<String, Object>();
            for (int i = 0; i < keys.length; i++) {
                mapValue.put(keys[i], getFieldValueByName(keys[i], project));
            }

            listmap.add(mapValue);
        }
        return listmap;
    }

    /**
     * 利用反射  根据属性名获取属性值
     */
    private static Object getFieldValueByName(String fieldName, Object o) {
        try {
            String firstLetter = fieldName.substring(0, 1).toUpperCase();
            String getter = "get" + firstLetter + fieldName.substring(1);
            Method method = o.getClass().getMethod(getter);
            Object value = method.invoke(o);
            return value;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 创建excel文档对象
     *
     * @param keys        list中map的key数组集合
     * @param columnNames excel的列名
     */
    private static Workbook createWorkBook(List<Map<String, Object>> list, String[] keys, String[] columnNames) {
        // 创建excel工作簿
        Workbook wb = new XSSFWorkbook();

        // 创建第一个sheet（页），并命名
        Sheet sheet = wb.createSheet(list.get(0).get("sheetName").toString());
        // 手动设置列宽。第一个参数表示要为第几列设；，第二个参数表示列的宽度，n为列高的像素数。
        for (int i = 0; i < keys.length; i++) {
            sheet.setColumnWidth((short) i, (short) (35.7 * 150));
        }

        // 创建第一行
        Row row = sheet.createRow((short) 0);

        // 创建两种单元格格式
        CellStyle cs = wb.createCellStyle();
        CellStyle cs2 = wb.createCellStyle();

        // 创建两种字体
        Font f = wb.createFont();
        Font f2 = wb.createFont();

        // 创建第一种字体样式（用于列名）
        f.setFontHeightInPoints((short) 10);
        f.setColor(IndexedColors.BLACK.getIndex());
        f.setBold(true);

        // 创建第二种字体样式（用于值）
        f2.setFontHeightInPoints((short) 10);
        f2.setColor(IndexedColors.BLACK.getIndex());

        // 设置第一种单元格的样式（用于列名）
        cs.setFont(f);
        cs.setBorderLeft(BorderStyle.THIN);
        cs.setBorderRight(BorderStyle.THIN);
        cs.setBorderTop(BorderStyle.THIN);
        cs.setBorderBottom(BorderStyle.THIN);
        cs.setAlignment(HorizontalAlignment.CENTER);

        // 设置第二种单元格的样式（用于值）
        cs2.setFont(f2);
        cs2.setBorderLeft(BorderStyle.THIN);
        cs2.setBorderRight(BorderStyle.THIN);
        cs2.setBorderTop(BorderStyle.THIN);
        cs2.setBorderBottom(BorderStyle.THIN);
        cs2.setAlignment(HorizontalAlignment.CENTER);
        //设置列名
        for (int i = 0; i < columnNames.length; i++) {
            Cell cell = row.createCell(i);
            cell.setCellValue(columnNames[i]);
            cell.setCellStyle(cs);
        }
        //设置每行每列的值
        for (short i = 1; i < list.size(); i++) {
            // Row 行,Cell 方格 , Row 和 Cell 都是从0开始计数的
            // 创建一行，在页sheet上
            Row row1 = sheet.createRow(i);
            // 在row行上创建一个方格
            for (short j = 0; j < keys.length; j++) {
                Cell cell = row1.createCell(j);
                cell.setCellValue(list.get(i).get(keys[j]) == null ? " " : list.get(i).get(keys[j]).toString());
                cell.setCellStyle(cs2);
            }
        }
        return wb;
    }




}