基于POI的Excel导入导出工具ExcelUtil

时间:2019-01-22
本文章向大家介绍基于POI的Excel导入导出工具ExcelUtil，主要包括基于POI的Excel导入导出工具ExcelUtil使用实例、应用技巧、基本知识点总结和需要注意事项，具有一定的参考价值，需要的朋友可以参考一下。

关于excel的操作工具网上实在太多，但有两方面原因值得自己写一个：1）简单的导入导出功能的案例大同小异，自己写一个也浪费不了多少时间，2）成熟的git工具类功能过于臃肿，我仅仅需要个导入导出你让我依赖你一个完整的package?

一、核心工具类代码：

package com.roboadvisor.platform.util.excelUtil;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.formula.functions.T;
import org.apache.poi.ss.usermodel.CellType;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.util.IOUtils;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.web.multipart.MultipartFile;
import com.roboadvisor.platform.entity.excelEntity.ExcelFiled;

/**
 * excel解析工具
 * @author fujian
 *
 */
public class ExcelUtil {

	/**
	 * 根据clazz定义的column解析excel文件
	 * @param excel
	 * @param clazz
	 */
	
	public static <T> List<T> parse(MultipartFile excel, Class<T> clazz) {
		
		try {
			File tmpFile = File.createTempFile(excel.getOriginalFilename().substring(0, excel.getOriginalFilename().lastIndexOf(".")), excel.getOriginalFilename().substring(excel.getOriginalFilename().lastIndexOf(".")+1));
			excel.transferTo(tmpFile);
			Workbook workbook = getWorkBook(tmpFile);
			Sheet sheet = workbook.getSheetAt(0);
			return parseSheet(sheet, clazz);
			
			
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return null;
	}
	
	private static Workbook getWorkBook(File file) {
		FileInputStream fis = null;
		try {
			fis = new FileInputStream(file);
			if(file.getName().endsWith("xls")) {
				return new HSSFWorkbook(fis);
			}
			if(file.getName().endsWith("xlsx")) {
				return new XSSFWorkbook(fis);
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			IOUtils.closeQuietly(fis);
		}
		return null;
	}
	
	private static <T> List<T> parseSheet(Sheet sheet, Class<T> clazz) {
		List<T> result = new ArrayList<>();
		Map<String, Integer> field2ColNum = new HashMap<>();
		Field[] fields = clazz.getDeclaredFields();
		for(Field field : fields) {
			if(!field.isAccessible()) {
				field.setAccessible(true);
			}
			ExcelFiled anno = field.getDeclaredAnnotation(ExcelFiled.class);
			if(null != anno) {
				field2ColNum.put(field.getName(), anno.columnNum());
			}
		}
		
		for(int rowNum =1; rowNum<sheet.getLastRowNum(); rowNum++) {
			Row row = sheet.getRow(rowNum);
			try {
				T object = clazz.newInstance();
				for(String filedName : field2ColNum.keySet()) {
					int cellNum = field2ColNum.get(filedName);
					Method method = clazz.getDeclaredMethod("set"+filedName.replaceAll("^\\w", String.valueOf(filedName.charAt(0)).toUpperCase()), String.class);
					if(CellType.STRING != row.getCell(cellNum).getCellType()) {
						method.invoke(object, String.valueOf(row.getCell(cellNum).getNumericCellValue()).replaceAll("\\.\\d+", ""));
					} else {
						method.invoke(object, row.getCell(cellNum).getStringCellValue());
					}
				}
				result.add(object);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
		}
		return result;
	}
	
	/**
	 * 将list中的数据写入excel
	 * @param list
	 * @return
	 */
	public static <T> InputStream exportExcel(List<T> list) {
		InputStream excel = null;
		if(list.isEmpty()) {
			return excel;
		}
		
		Workbook workbook = new XSSFWorkbook();
		Sheet sheet = workbook.createSheet();
		Row headerRow = sheet.createRow(0);
		Class<?> clazz = list.get(0).getClass();
		
		Map<String, Integer> field2ColNum = new HashMap<>();
		Field[] fields = clazz.getDeclaredFields();
		for(Field field : fields) {
			if(!field.isAccessible()) {
				field.setAccessible(true);
			}
			ExcelFiled anno = field.getDeclaredAnnotation(ExcelFiled.class);
			if(null != anno) {
				field2ColNum.put(field.getName(), anno.columnNum());
				headerRow.createCell(anno.columnNum()).setCellValue(anno.columnName());
			}
		}
		Set<String> fileds = field2ColNum.keySet();
		for(int i=0; i<list.size(); i++) {
			Row row = sheet.createRow(i+1);
			for(String field : fileds) {
				try {
					Method method = clazz.getDeclaredMethod("get"+field.replaceAll("^\\w", String.valueOf(field.charAt(0)).toUpperCase()));
					String object = String.valueOf(method.invoke(list.get(i)));
					row.createCell(field2ColNum.get(field)).setCellValue(object);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
		
		for(int i=0; i<fields.length; i++) {
			sheet.autoSizeColumn(i);
		}
		
		try {
			ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
			workbook.write(outputStream);
			excel = new ByteArrayInputStream(outputStream.toByteArray());
			workbook.close();
			return excel;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return excel;
	}
}

二、与excel中内容对应的实体类上需添加的注解如下：

package com.roboadvisor.platform.entity.excelEntity;

import lombok.Getter;
import lombok.Setter;

@Setter
@Getter
public class ExcelEntity {

	
	private String poolId;
	@ExcelFiled(columnName="基金代码", columnNum=0)
	private String securityId;
	@ExcelFiled(columnName="基金名称", columnNum=1)
	private String secName;
	@ExcelFiled(columnName="产品类型", columnNum=2)
	private String secType;
	
}

columnName为列名称，中文名称
columnNum为列数，0-based

三、service层调用excel工具类

package com.roboadvisor.platform.service;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.List;

import javax.servlet.http.HttpServletResponse;

import org.apache.commons.compress.utils.IOUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;
import com.roboadvisor.platform.entity.excelEntity.ExcelEntity;
import com.roboadvisor.platform.mapper.FileImportMapper;
import com.roboadvisor.platform.util.excelUtil.ExcelUtil;
import com.roboadvisor.platform.util.resultEntity.ResultEntity;
import com.roboadvisor.platform.util.resultEntity.ResultStatus;

@Service
public class FileImportService {

	@Autowired
	private FileImportMapper mapper;
	
	/**
	 * excel内容导入db
	 * @param excel
	 * @return
	 */
	public ResultEntity<String> importExcel(MultipartFile excel) {
		
		List<ExcelEntity> entities = ExcelUtil.parse(excel, ExcelEntity.class);
		
		mapper.insertList(entities);
		
		return new ResultEntity<>(ResultStatus.OK);
		
	}
	/**
	 * db内容写入excel
	 * @param entities
	 * @throws UnsupportedEncodingException 
	 */
	public void exportExcel(HttpServletResponse response) throws UnsupportedEncodingException {
		
		List<ExcelEntity> list = mapper.getFromDB();
		
		InputStream in = ExcelUtil.exportExcel(list);
		response.reset();
		response.setContentType("multipart/form-data");
		response.setCharacterEncoding("UTF-8");
		String fielname = URLEncoder.encode("export-excel.xlsx", "UTF-8");
		response.setHeader("Content-Disposition", "attachment; filename=" + fielname);
		byte[] buffer = new byte[1024]; 
		int length;
		try {
			while((length = in.read(buffer)) >0) {
				response.getOutputStream().write(buffer, 0, length);
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			IOUtils.closeQuietly(in);
		}	
	}	 
}
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