poi、Excel工具包，支持map转excel，bean转excel

参数有表头：linkedHashMap的key要与内容的key一致

表内容：map的key或者bean的属性名要与表头的数据保持一致，不要求顺序。

默认保存到系统的临时文件。

下面是代码

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.lang.reflect.Field;
import java.util.*;

/**
 * @author niexiang
 * @Description
 * @create 2017-12-13 16:18
 **/
public class PoiUtil {

    /**
     * Map生成excel表
     * @param head (头部的key必须对应map的key)
     * @param contents
     * @return 返回保存的地址
     */
    public static String mapToExcel(LinkedHashMap<String,String> head, List<Map> contents,String sheetName,String fileName) {
        HSSFWorkbook workbook = new HSSFWorkbook();
        HSSFSheet sheet = workbook.createSheet(sheetName);
        //生成内容
        for (int i = 0;i< contents.size()+1;i++){//excel的行数
            HSSFRow row = sheet.createRow(i);
            int j = 0;//列
            for (Map.Entry<String,String> property : head.entrySet()) {
                HSSFCell cell = row.createCell(j++);
                if (i == 0) {//表头信息
                    cell.setCellValue(property.getValue());
                }else{
                    cell.setCellValue(contents.get(i - 1).get(property.getKey()) == null ? null :contents.get(i - 1).get(property.getKey()).toString());
                }
            }
        }
        String folder=System.getProperty("java.io.tmpdir");
        String filePath = folder + "/" + fileName;
        return writeFile(workbook,filePath);
    }

    /**
     * bean生成excel表
     * @param head (头部的key必须对应bean的属性名)
     * @param contents
     * @return 返回保存的地址
     */
    public static <T> String beanToExcel(LinkedHashMap<String,String> head, List<T> contents,String sheetName,String fileName) throws Exception {
        HSSFWorkbook workbook = new HSSFWorkbook();
        HSSFSheet sheet = workbook.createSheet(sheetName);
        Class clazz = contents.get(0).getClass();
        //生成内容
        for (int i = 0;i< contents.size()+1;i++){//excel的行数
            HSSFRow row = sheet.createRow(i);
            int j = 0;//列
            for (Map.Entry<String,String> property : head.entrySet()) {
                HSSFCell cell = row.createCell(j++);
                if (i == 0) {//表头信息
                    cell.setCellValue(property.getValue());
                }else{
                    Field field = clazz.getDeclaredField(property.getKey());
                    field.setAccessible(true);
                    Object result = field.get(contents.get(i - 1));
                    cell.setCellValue(result == null ? null :result.toString());
                }
            }
        }
        String folder=System.getProperty("java.io.tmpdir");
        String filePath = folder + fileName;
        return writeFile(workbook,filePath);
    }

    private static String writeFile(HSSFWorkbook workbook, String filePath) {
        FileOutputStream stream = null;
        BufferedOutputStream outputStream = null;
        try {
            stream = new FileOutputStream(filePath);
            outputStream = new BufferedOutputStream(stream);
            workbook.write(outputStream);
            return filePath;
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (outputStream != null){
                try {
                    outputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (stream != null){
                try {
                    stream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return null;
    }


    public static void main(String[] args) {
        LinkedHashMap<String,String> map = new LinkedHashMap<>();
        map.put("name","姓名");
        map.put("age","年龄");
        map.put("gender","性别");
        List<Person> list = new ArrayList<>();
        for (int i = 0; i < 10 ; i++) {
            list.add(new Person("123",i,"男"));
        }
        try {
            beanToExcel(map,list,"ceshi123","ceshi123.xls");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


}